1/*
   2 * Generic hugetlb support.
   3 * (C) Nadia Yvette Chambers, April 2004
   4 */
   5#include <linux/list.h>
   6#include <linux/init.h>
   7#include <linux/mm.h>
   8#include <linux/seq_file.h>
   9#include <linux/sysctl.h>
  10#include <linux/highmem.h>
  11#include <linux/mmu_notifier.h>
  12#include <linux/nodemask.h>
  13#include <linux/pagemap.h>
  14#include <linux/mempolicy.h>
  15#include <linux/compiler.h>
  16#include <linux/cpuset.h>
  17#include <linux/mutex.h>
  18#include <linux/bootmem.h>
  19#include <linux/sysfs.h>
  20#include <linux/slab.h>
 
  21#include <linux/mmdebug.h>
  22#include <linux/sched/signal.h>
  23#include <linux/rmap.h>
  24#include <linux/string_helpers.h>
  25#include <linux/swap.h>
  26#include <linux/swapops.h>
  27#include <linux/jhash.h>
 
 
 
 
 
 
 
  28
  29#include <asm/page.h>
  30#include <asm/pgtable.h>
  31#include <asm/tlb.h>
  32
  33#include <linux/io.h>
  34#include <linux/hugetlb.h>
  35#include <linux/hugetlb_cgroup.h>
  36#include <linux/node.h>
  37#include <linux/userfaultfd_k.h>
  38#include <linux/page_owner.h>
  39#include "internal.h"
 
  40
  41int hugetlb_max_hstate __read_mostly;
  42unsigned int default_hstate_idx;
  43struct hstate hstates[HUGE_MAX_HSTATE];
  44/*
  45 * Minimum page order among possible hugepage sizes, set to a proper value
  46 * at boot time.
  47 */
  48static unsigned int minimum_order __read_mostly = UINT_MAX;
 
 
 
 
 
 
 
 
 
 
 
  49
  50__initdata LIST_HEAD(huge_boot_pages);
  51
  52/* for command line parsing */
  53static struct hstate * __initdata parsed_hstate;
  54static unsigned long __initdata default_hstate_max_huge_pages;
  55static unsigned long __initdata default_hstate_size;
  56static bool __initdata parsed_valid_hugepagesz = true;
 
 
  57
  58/*
  59 * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
  60 * free_huge_pages, and surplus_huge_pages.
  61 */
  62DEFINE_SPINLOCK(hugetlb_lock);
  63
  64/*
  65 * Serializes faults on the same logical page.  This is used to
  66 * prevent spurious OOMs when the hugepage pool is fully utilized.
  67 */
  68static int num_fault_mutexes;
  69struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
  70
  71/* Forward declaration */
  72static int hugetlb_acct_memory(struct hstate *h, long delta);
 
 
 
 
 
  73
  74static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
  75{
  76	bool free = (spool->count == 0) && (spool->used_hpages == 0);
 
 
 
 
 
  77
  78	spin_unlock(&spool->lock);
 
 
 
 
 
 
  79
  80	/* If no pages are used, and no other handles to the subpool
  81	 * remain, give up any reservations mased on minimum size and
  82	 * free the subpool */
  83	if (free) {
  84		if (spool->min_hpages != -1)
  85			hugetlb_acct_memory(spool->hstate,
  86						-spool->min_hpages);
  87		kfree(spool);
  88	}
  89}
  90
  91struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
  92						long min_hpages)
  93{
  94	struct hugepage_subpool *spool;
  95
  96	spool = kzalloc(sizeof(*spool), GFP_KERNEL);
  97	if (!spool)
  98		return NULL;
  99
 100	spin_lock_init(&spool->lock);
 101	spool->count = 1;
 102	spool->max_hpages = max_hpages;
 103	spool->hstate = h;
 104	spool->min_hpages = min_hpages;
 105
 106	if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) {
 107		kfree(spool);
 108		return NULL;
 109	}
 110	spool->rsv_hpages = min_hpages;
 111
 112	return spool;
 113}
 114
 115void hugepage_put_subpool(struct hugepage_subpool *spool)
 116{
 117	spin_lock(&spool->lock);
 
 
 118	BUG_ON(!spool->count);
 119	spool->count--;
 120	unlock_or_release_subpool(spool);
 121}
 122
 123/*
 124 * Subpool accounting for allocating and reserving pages.
 125 * Return -ENOMEM if there are not enough resources to satisfy the
 126 * the request.  Otherwise, return the number of pages by which the
 127 * global pools must be adjusted (upward).  The returned value may
 128 * only be different than the passed value (delta) in the case where
 129 * a subpool minimum size must be manitained.
 130 */
 131static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
 132				      long delta)
 133{
 134	long ret = delta;
 135
 136	if (!spool)
 137		return ret;
 138
 139	spin_lock(&spool->lock);
 140
 141	if (spool->max_hpages != -1) {		/* maximum size accounting */
 142		if ((spool->used_hpages + delta) <= spool->max_hpages)
 143			spool->used_hpages += delta;
 144		else {
 145			ret = -ENOMEM;
 146			goto unlock_ret;
 147		}
 148	}
 149
 150	/* minimum size accounting */
 151	if (spool->min_hpages != -1 && spool->rsv_hpages) {
 152		if (delta > spool->rsv_hpages) {
 153			/*
 154			 * Asking for more reserves than those already taken on
 155			 * behalf of subpool.  Return difference.
 156			 */
 157			ret = delta - spool->rsv_hpages;
 158			spool->rsv_hpages = 0;
 159		} else {
 160			ret = 0;	/* reserves already accounted for */
 161			spool->rsv_hpages -= delta;
 162		}
 163	}
 164
 165unlock_ret:
 166	spin_unlock(&spool->lock);
 167	return ret;
 168}
 169
 170/*
 171 * Subpool accounting for freeing and unreserving pages.
 172 * Return the number of global page reservations that must be dropped.
 173 * The return value may only be different than the passed value (delta)
 174 * in the case where a subpool minimum size must be maintained.
 175 */
 176static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
 177				       long delta)
 178{
 179	long ret = delta;
 
 180
 181	if (!spool)
 182		return delta;
 183
 184	spin_lock(&spool->lock);
 185
 186	if (spool->max_hpages != -1)		/* maximum size accounting */
 187		spool->used_hpages -= delta;
 188
 189	 /* minimum size accounting */
 190	if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
 191		if (spool->rsv_hpages + delta <= spool->min_hpages)
 192			ret = 0;
 193		else
 194			ret = spool->rsv_hpages + delta - spool->min_hpages;
 195
 196		spool->rsv_hpages += delta;
 197		if (spool->rsv_hpages > spool->min_hpages)
 198			spool->rsv_hpages = spool->min_hpages;
 199	}
 200
 201	/*
 202	 * If hugetlbfs_put_super couldn't free spool due to an outstanding
 203	 * quota reference, free it now.
 204	 */
 205	unlock_or_release_subpool(spool);
 206
 207	return ret;
 208}
 209
 210static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
 211{
 212	return HUGETLBFS_SB(inode->i_sb)->spool;
 213}
 214
 215static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
 216{
 217	return subpool_inode(file_inode(vma->vm_file));
 218}
 219
 220/*
 221 * Region tracking -- allows tracking of reservations and instantiated pages
 222 *                    across the pages in a mapping.
 223 *
 224 * The region data structures are embedded into a resv_map and protected
 225 * by a resv_map's lock.  The set of regions within the resv_map represent
 226 * reservations for huge pages, or huge pages that have already been
 227 * instantiated within the map.  The from and to elements are huge page
 228 * indicies into the associated mapping.  from indicates the starting index
 229 * of the region.  to represents the first index past the end of  the region.
 230 *
 231 * For example, a file region structure with from == 0 and to == 4 represents
 232 * four huge pages in a mapping.  It is important to note that the to element
 233 * represents the first element past the end of the region. This is used in
 234 * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 235 *
 236 * Interval notation of the form [from, to) will be used to indicate that
 237 * the endpoint from is inclusive and to is exclusive.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 238 */
 239struct file_region {
 240	struct list_head link;
 241	long from;
 242	long to;
 243};
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 244
 245/*
 246 * Add the huge page range represented by [f, t) to the reserve
 247 * map.  In the normal case, existing regions will be expanded
 248 * to accommodate the specified range.  Sufficient regions should
 249 * exist for expansion due to the previous call to region_chg
 250 * with the same range.  However, it is possible that region_del
 251 * could have been called after region_chg and modifed the map
 252 * in such a way that no region exists to be expanded.  In this
 253 * case, pull a region descriptor from the cache associated with
 254 * the map and use that for the new range.
 255 *
 256 * Return the number of new huge pages added to the map.  This
 257 * number is greater than or equal to zero.
 258 */
 259static long region_add(struct resv_map *resv, long f, long t)
 
 
 
 
 
 
 
 
 260{
 261	struct list_head *head = &resv->regions;
 262	struct file_region *rg, *nrg, *trg;
 263	long add = 0;
 264
 265	spin_lock(&resv->lock);
 266	/* Locate the region we are either in or before. */
 267	list_for_each_entry(rg, head, link)
 268		if (f <= rg->to)
 269			break;
 
 270
 271	/*
 272	 * If no region exists which can be expanded to include the
 273	 * specified range, the list must have been modified by an
 274	 * interleving call to region_del().  Pull a region descriptor
 275	 * from the cache and use it for this range.
 276	 */
 277	if (&rg->link == head || t < rg->from) {
 278		VM_BUG_ON(resv->region_cache_count <= 0);
 279
 280		resv->region_cache_count--;
 281		nrg = list_first_entry(&resv->region_cache, struct file_region,
 282					link);
 283		list_del(&nrg->link);
 284
 285		nrg->from = f;
 286		nrg->to = t;
 287		list_add(&nrg->link, rg->link.prev);
 288
 289		add += t - f;
 290		goto out_locked;
 291	}
 292
 293	/* Round our left edge to the current segment if it encloses us. */
 294	if (f > rg->from)
 295		f = rg->from;
 296
 297	/* Check for and consume any regions we now overlap with. */
 298	nrg = rg;
 299	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
 300		if (&rg->link == head)
 301			break;
 302		if (rg->from > t)
 303			break;
 304
 305		/* If this area reaches higher then extend our area to
 306		 * include it completely.  If this is not the first area
 307		 * which we intend to reuse, free it. */
 308		if (rg->to > t)
 309			t = rg->to;
 310		if (rg != nrg) {
 311			/* Decrement return value by the deleted range.
 312			 * Another range will span this area so that by
 313			 * end of routine add will be >= zero
 314			 */
 315			add -= (rg->to - rg->from);
 316			list_del(&rg->link);
 317			kfree(rg);
 318		}
 
 
 319	}
 320
 321	add += (nrg->from - f);		/* Added to beginning of region */
 322	nrg->from = f;
 323	add += t - nrg->to;		/* Added to end of region */
 324	nrg->to = t;
 325
 326out_locked:
 327	resv->adds_in_progress--;
 328	spin_unlock(&resv->lock);
 329	VM_BUG_ON(add < 0);
 330	return add;
 331}
 332
 333/*
 334 * Examine the existing reserve map and determine how many
 335 * huge pages in the specified range [f, t) are NOT currently
 336 * represented.  This routine is called before a subsequent
 337 * call to region_add that will actually modify the reserve
 338 * map to add the specified range [f, t).  region_chg does
 339 * not change the number of huge pages represented by the
 340 * map.  However, if the existing regions in the map can not
 341 * be expanded to represent the new range, a new file_region
 342 * structure is added to the map as a placeholder.  This is
 343 * so that the subsequent region_add call will have all the
 344 * regions it needs and will not fail.
 345 *
 346 * Upon entry, region_chg will also examine the cache of region descriptors
 347 * associated with the map.  If there are not enough descriptors cached, one
 348 * will be allocated for the in progress add operation.
 349 *
 350 * Returns the number of huge pages that need to be added to the existing
 351 * reservation map for the range [f, t).  This number is greater or equal to
 352 * zero.  -ENOMEM is returned if a new file_region structure or cache entry
 353 * is needed and can not be allocated.
 354 */
 355static long region_chg(struct resv_map *resv, long f, long t)
 
 356{
 357	struct list_head *head = &resv->regions;
 358	struct file_region *rg, *nrg = NULL;
 359	long chg = 0;
 360
 361retry:
 362	spin_lock(&resv->lock);
 363retry_locked:
 364	resv->adds_in_progress++;
 365
 366	/*
 367	 * Check for sufficient descriptors in the cache to accommodate
 368	 * the number of in progress add operations.
 369	 */
 370	if (resv->adds_in_progress > resv->region_cache_count) {
 371		struct file_region *trg;
 372
 373		VM_BUG_ON(resv->adds_in_progress - resv->region_cache_count > 1);
 374		/* Must drop lock to allocate a new descriptor. */
 375		resv->adds_in_progress--;
 376		spin_unlock(&resv->lock);
 377
 378		trg = kmalloc(sizeof(*trg), GFP_KERNEL);
 379		if (!trg) {
 380			kfree(nrg);
 381			return -ENOMEM;
 382		}
 383
 384		spin_lock(&resv->lock);
 385		list_add(&trg->link, &resv->region_cache);
 386		resv->region_cache_count++;
 387		goto retry_locked;
 388	}
 389
 390	/* Locate the region we are before or in. */
 391	list_for_each_entry(rg, head, link)
 392		if (f <= rg->to)
 393			break;
 394
 395	/* If we are below the current region then a new region is required.
 396	 * Subtle, allocate a new region at the position but make it zero
 397	 * size such that we can guarantee to record the reservation. */
 398	if (&rg->link == head || t < rg->from) {
 399		if (!nrg) {
 400			resv->adds_in_progress--;
 401			spin_unlock(&resv->lock);
 402			nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
 403			if (!nrg)
 404				return -ENOMEM;
 405
 406			nrg->from = f;
 407			nrg->to   = f;
 408			INIT_LIST_HEAD(&nrg->link);
 409			goto retry;
 410		}
 411
 412		list_add(&nrg->link, rg->link.prev);
 413		chg = t - f;
 414		goto out_nrg;
 415	}
 416
 417	/* Round our left edge to the current segment if it encloses us. */
 418	if (f > rg->from)
 419		f = rg->from;
 420	chg = t - f;
 421
 422	/* Check for and consume any regions we now overlap with. */
 423	list_for_each_entry(rg, rg->link.prev, link) {
 424		if (&rg->link == head)
 425			break;
 426		if (rg->from > t)
 427			goto out;
 428
 429		/* We overlap with this area, if it extends further than
 430		 * us then we must extend ourselves.  Account for its
 431		 * existing reservation. */
 432		if (rg->to > t) {
 433			chg += rg->to - t;
 434			t = rg->to;
 435		}
 436		chg -= rg->to - rg->from;
 437	}
 438
 439out:
 440	spin_unlock(&resv->lock);
 441	/*  We already know we raced and no longer need the new region */
 442	kfree(nrg);
 443	return chg;
 444out_nrg:
 445	spin_unlock(&resv->lock);
 446	return chg;
 447}
 448
 449/*
 450 * Abort the in progress add operation.  The adds_in_progress field
 451 * of the resv_map keeps track of the operations in progress between
 452 * calls to region_chg and region_add.  Operations are sometimes
 453 * aborted after the call to region_chg.  In such cases, region_abort
 454 * is called to decrement the adds_in_progress counter.
 
 
 455 *
 456 * NOTE: The range arguments [f, t) are not needed or used in this
 457 * routine.  They are kept to make reading the calling code easier as
 458 * arguments will match the associated region_chg call.
 459 */
 460static void region_abort(struct resv_map *resv, long f, long t)
 
 461{
 462	spin_lock(&resv->lock);
 463	VM_BUG_ON(!resv->region_cache_count);
 464	resv->adds_in_progress--;
 465	spin_unlock(&resv->lock);
 466}
 467
 468/*
 469 * Delete the specified range [f, t) from the reserve map.  If the
 470 * t parameter is LONG_MAX, this indicates that ALL regions after f
 471 * should be deleted.  Locate the regions which intersect [f, t)
 472 * and either trim, delete or split the existing regions.
 473 *
 474 * Returns the number of huge pages deleted from the reserve map.
 475 * In the normal case, the return value is zero or more.  In the
 476 * case where a region must be split, a new region descriptor must
 477 * be allocated.  If the allocation fails, -ENOMEM will be returned.
 478 * NOTE: If the parameter t == LONG_MAX, then we will never split
 479 * a region and possibly return -ENOMEM.  Callers specifying
 480 * t == LONG_MAX do not need to check for -ENOMEM error.
 481 */
 482static long region_del(struct resv_map *resv, long f, long t)
 483{
 484	struct list_head *head = &resv->regions;
 485	struct file_region *rg, *trg;
 486	struct file_region *nrg = NULL;
 487	long del = 0;
 488
 489retry:
 490	spin_lock(&resv->lock);
 491	list_for_each_entry_safe(rg, trg, head, link) {
 492		/*
 493		 * Skip regions before the range to be deleted.  file_region
 494		 * ranges are normally of the form [from, to).  However, there
 495		 * may be a "placeholder" entry in the map which is of the form
 496		 * (from, to) with from == to.  Check for placeholder entries
 497		 * at the beginning of the range to be deleted.
 498		 */
 499		if (rg->to <= f && (rg->to != rg->from || rg->to != f))
 500			continue;
 501
 502		if (rg->from >= t)
 503			break;
 504
 505		if (f > rg->from && t < rg->to) { /* Must split region */
 506			/*
 507			 * Check for an entry in the cache before dropping
 508			 * lock and attempting allocation.
 509			 */
 510			if (!nrg &&
 511			    resv->region_cache_count > resv->adds_in_progress) {
 512				nrg = list_first_entry(&resv->region_cache,
 513							struct file_region,
 514							link);
 515				list_del(&nrg->link);
 516				resv->region_cache_count--;
 517			}
 518
 519			if (!nrg) {
 520				spin_unlock(&resv->lock);
 521				nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
 522				if (!nrg)
 523					return -ENOMEM;
 524				goto retry;
 525			}
 526
 527			del += t - f;
 
 
 528
 529			/* New entry for end of split region */
 530			nrg->from = t;
 531			nrg->to = rg->to;
 
 
 
 532			INIT_LIST_HEAD(&nrg->link);
 533
 534			/* Original entry is trimmed */
 535			rg->to = f;
 536
 537			list_add(&nrg->link, &rg->link);
 538			nrg = NULL;
 539			break;
 540		}
 541
 542		if (f <= rg->from && t >= rg->to) { /* Remove entire region */
 543			del += rg->to - rg->from;
 
 
 544			list_del(&rg->link);
 545			kfree(rg);
 546			continue;
 547		}
 548
 549		if (f <= rg->from) {	/* Trim beginning of region */
 
 
 
 550			del += t - rg->from;
 551			rg->from = t;
 552		} else {		/* Trim end of region */
 
 
 
 553			del += rg->to - f;
 554			rg->to = f;
 555		}
 556	}
 557
 558	spin_unlock(&resv->lock);
 559	kfree(nrg);
 560	return del;
 561}
 562
 563/*
 564 * A rare out of memory error was encountered which prevented removal of
 565 * the reserve map region for a page.  The huge page itself was free'ed
 566 * and removed from the page cache.  This routine will adjust the subpool
 567 * usage count, and the global reserve count if needed.  By incrementing
 568 * these counts, the reserve map entry which could not be deleted will
 569 * appear as a "reserved" entry instead of simply dangling with incorrect
 570 * counts.
 571 */
 572void hugetlb_fix_reserve_counts(struct inode *inode)
 573{
 574	struct hugepage_subpool *spool = subpool_inode(inode);
 575	long rsv_adjust;
 
 576
 577	rsv_adjust = hugepage_subpool_get_pages(spool, 1);
 578	if (rsv_adjust) {
 579		struct hstate *h = hstate_inode(inode);
 580
 581		hugetlb_acct_memory(h, 1);
 
 
 
 582	}
 
 
 
 583}
 584
 585/*
 586 * Count and return the number of huge pages in the reserve map
 587 * that intersect with the range [f, t).
 588 */
 589static long region_count(struct resv_map *resv, long f, long t)
 590{
 591	struct list_head *head = &resv->regions;
 592	struct file_region *rg;
 593	long chg = 0;
 594
 595	spin_lock(&resv->lock);
 596	/* Locate each segment we overlap with, and count that overlap. */
 597	list_for_each_entry(rg, head, link) {
 598		long seg_from;
 599		long seg_to;
 600
 601		if (rg->to <= f)
 602			continue;
 603		if (rg->from >= t)
 604			break;
 605
 606		seg_from = max(rg->from, f);
 607		seg_to = min(rg->to, t);
 608
 609		chg += seg_to - seg_from;
 610	}
 611	spin_unlock(&resv->lock);
 612
 613	return chg;
 614}
 615
 616/*
 617 * Convert the address within this vma to the page offset within
 618 * the mapping, in pagecache page units; huge pages here.
 619 */
 620static pgoff_t vma_hugecache_offset(struct hstate *h,
 621			struct vm_area_struct *vma, unsigned long address)
 622{
 623	return ((address - vma->vm_start) >> huge_page_shift(h)) +
 624			(vma->vm_pgoff >> huge_page_order(h));
 625}
 626
 627pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
 628				     unsigned long address)
 629{
 630	return vma_hugecache_offset(hstate_vma(vma), vma, address);
 631}
 632EXPORT_SYMBOL_GPL(linear_hugepage_index);
 633
 634/*
 635 * Return the size of the pages allocated when backing a VMA. In the majority
 636 * cases this will be same size as used by the page table entries.
 637 */
 638unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
 639{
 640	if (vma->vm_ops && vma->vm_ops->pagesize)
 641		return vma->vm_ops->pagesize(vma);
 642	return PAGE_SIZE;
 643}
 644EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
 645
 646/*
 647 * Return the page size being used by the MMU to back a VMA. In the majority
 648 * of cases, the page size used by the kernel matches the MMU size. On
 649 * architectures where it differs, an architecture-specific 'strong'
 650 * version of this symbol is required.
 651 */
 652__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
 653{
 654	return vma_kernel_pagesize(vma);
 655}
 656
 657/*
 658 * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
 659 * bits of the reservation map pointer, which are always clear due to
 660 * alignment.
 661 */
 662#define HPAGE_RESV_OWNER    (1UL << 0)
 663#define HPAGE_RESV_UNMAPPED (1UL << 1)
 664#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
 665
 666/*
 667 * These helpers are used to track how many pages are reserved for
 668 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
 669 * is guaranteed to have their future faults succeed.
 670 *
 671 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
 672 * the reserve counters are updated with the hugetlb_lock held. It is safe
 673 * to reset the VMA at fork() time as it is not in use yet and there is no
 674 * chance of the global counters getting corrupted as a result of the values.
 675 *
 676 * The private mapping reservation is represented in a subtly different
 677 * manner to a shared mapping.  A shared mapping has a region map associated
 678 * with the underlying file, this region map represents the backing file
 679 * pages which have ever had a reservation assigned which this persists even
 680 * after the page is instantiated.  A private mapping has a region map
 681 * associated with the original mmap which is attached to all VMAs which
 682 * reference it, this region map represents those offsets which have consumed
 683 * reservation ie. where pages have been instantiated.
 684 */
 685static unsigned long get_vma_private_data(struct vm_area_struct *vma)
 686{
 687	return (unsigned long)vma->vm_private_data;
 688}
 689
 690static void set_vma_private_data(struct vm_area_struct *vma,
 691							unsigned long value)
 692{
 693	vma->vm_private_data = (void *)value;
 694}
 695
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 696struct resv_map *resv_map_alloc(void)
 697{
 698	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
 699	struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL);
 700
 701	if (!resv_map || !rg) {
 702		kfree(resv_map);
 703		kfree(rg);
 704		return NULL;
 705	}
 706
 707	kref_init(&resv_map->refs);
 708	spin_lock_init(&resv_map->lock);
 709	INIT_LIST_HEAD(&resv_map->regions);
 710
 711	resv_map->adds_in_progress = 0;
 
 
 
 
 
 
 
 712
 713	INIT_LIST_HEAD(&resv_map->region_cache);
 714	list_add(&rg->link, &resv_map->region_cache);
 715	resv_map->region_cache_count = 1;
 716
 717	return resv_map;
 718}
 719
 720void resv_map_release(struct kref *ref)
 721{
 722	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
 723	struct list_head *head = &resv_map->region_cache;
 724	struct file_region *rg, *trg;
 725
 726	/* Clear out any active regions before we release the map. */
 727	region_del(resv_map, 0, LONG_MAX);
 728
 729	/* ... and any entries left in the cache */
 730	list_for_each_entry_safe(rg, trg, head, link) {
 731		list_del(&rg->link);
 732		kfree(rg);
 733	}
 734
 735	VM_BUG_ON(resv_map->adds_in_progress);
 736
 737	kfree(resv_map);
 738}
 739
 740static inline struct resv_map *inode_resv_map(struct inode *inode)
 741{
 742	return inode->i_mapping->private_data;
 
 
 
 
 
 
 
 
 743}
 744
 745static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
 746{
 747	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 748	if (vma->vm_flags & VM_MAYSHARE) {
 749		struct address_space *mapping = vma->vm_file->f_mapping;
 750		struct inode *inode = mapping->host;
 751
 752		return inode_resv_map(inode);
 753
 754	} else {
 755		return (struct resv_map *)(get_vma_private_data(vma) &
 756							~HPAGE_RESV_MASK);
 757	}
 758}
 759
 760static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
 761{
 762	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 763	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
 764
 765	set_vma_private_data(vma, (get_vma_private_data(vma) &
 766				HPAGE_RESV_MASK) | (unsigned long)map);
 767}
 768
 769static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
 770{
 771	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 772	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
 773
 774	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
 775}
 776
 777static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
 778{
 779	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 780
 781	return (get_vma_private_data(vma) & flag) != 0;
 782}
 783
 784/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
 785void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
 786{
 787	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 788	if (!(vma->vm_flags & VM_MAYSHARE))
 789		vma->vm_private_data = (void *)0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 790}
 791
 792/* Returns true if the VMA has associated reserve pages */
 793static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
 794{
 795	if (vma->vm_flags & VM_NORESERVE) {
 796		/*
 797		 * This address is already reserved by other process(chg == 0),
 798		 * so, we should decrement reserved count. Without decrementing,
 799		 * reserve count remains after releasing inode, because this
 800		 * allocated page will go into page cache and is regarded as
 801		 * coming from reserved pool in releasing step.  Currently, we
 802		 * don't have any other solution to deal with this situation
 803		 * properly, so add work-around here.
 804		 */
 805		if (vma->vm_flags & VM_MAYSHARE && chg == 0)
 806			return true;
 807		else
 808			return false;
 809	}
 810
 811	/* Shared mappings always use reserves */
 812	if (vma->vm_flags & VM_MAYSHARE) {
 813		/*
 814		 * We know VM_NORESERVE is not set.  Therefore, there SHOULD
 815		 * be a region map for all pages.  The only situation where
 816		 * there is no region map is if a hole was punched via
 817		 * fallocate.  In this case, there really are no reverves to
 818		 * use.  This situation is indicated if chg != 0.
 819		 */
 820		if (chg)
 821			return false;
 822		else
 823			return true;
 824	}
 825
 826	/*
 827	 * Only the process that called mmap() has reserves for
 828	 * private mappings.
 829	 */
 830	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
 831		/*
 832		 * Like the shared case above, a hole punch or truncate
 833		 * could have been performed on the private mapping.
 834		 * Examine the value of chg to determine if reserves
 835		 * actually exist or were previously consumed.
 836		 * Very Subtle - The value of chg comes from a previous
 837		 * call to vma_needs_reserves().  The reserve map for
 838		 * private mappings has different (opposite) semantics
 839		 * than that of shared mappings.  vma_needs_reserves()
 840		 * has already taken this difference in semantics into
 841		 * account.  Therefore, the meaning of chg is the same
 842		 * as in the shared case above.  Code could easily be
 843		 * combined, but keeping it separate draws attention to
 844		 * subtle differences.
 845		 */
 846		if (chg)
 847			return false;
 848		else
 849			return true;
 850	}
 851
 852	return false;
 853}
 854
 855static void enqueue_huge_page(struct hstate *h, struct page *page)
 856{
 857	int nid = page_to_nid(page);
 858	list_move(&page->lru, &h->hugepage_freelists[nid]);
 
 
 
 
 859	h->free_huge_pages++;
 860	h->free_huge_pages_node[nid]++;
 
 861}
 862
 863static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
 864{
 865	struct page *page;
 
 866
 867	list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
 868		if (!PageHWPoison(page))
 869			break;
 870	/*
 871	 * if 'non-isolated free hugepage' not found on the list,
 872	 * the allocation fails.
 873	 */
 874	if (&h->hugepage_freelists[nid] == &page->lru)
 875		return NULL;
 876	list_move(&page->lru, &h->hugepage_activelist);
 877	set_page_refcounted(page);
 878	h->free_huge_pages--;
 879	h->free_huge_pages_node[nid]--;
 880	return page;
 
 
 
 881}
 882
 883static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid,
 884		nodemask_t *nmask)
 885{
 886	unsigned int cpuset_mems_cookie;
 887	struct zonelist *zonelist;
 888	struct zone *zone;
 889	struct zoneref *z;
 890	int node = -1;
 891
 892	zonelist = node_zonelist(nid, gfp_mask);
 893
 894retry_cpuset:
 895	cpuset_mems_cookie = read_mems_allowed_begin();
 896	for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
 897		struct page *page;
 898
 899		if (!cpuset_zone_allowed(zone, gfp_mask))
 900			continue;
 901		/*
 902		 * no need to ask again on the same node. Pool is node rather than
 903		 * zone aware
 904		 */
 905		if (zone_to_nid(zone) == node)
 906			continue;
 907		node = zone_to_nid(zone);
 908
 909		page = dequeue_huge_page_node_exact(h, node);
 910		if (page)
 911			return page;
 912	}
 913	if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie)))
 914		goto retry_cpuset;
 915
 916	return NULL;
 917}
 918
 919/* Movability of hugepages depends on migration support. */
 920static inline gfp_t htlb_alloc_mask(struct hstate *h)
 921{
 922	if (hugepage_migration_supported(h))
 923		return GFP_HIGHUSER_MOVABLE;
 924	else
 925		return GFP_HIGHUSER;
 926}
 927
 928static struct page *dequeue_huge_page_vma(struct hstate *h,
 929				struct vm_area_struct *vma,
 930				unsigned long address, int avoid_reserve,
 931				long chg)
 932{
 933	struct page *page;
 934	struct mempolicy *mpol;
 935	gfp_t gfp_mask;
 936	nodemask_t *nodemask;
 937	int nid;
 938
 939	/*
 940	 * A child process with MAP_PRIVATE mappings created by their parent
 941	 * have no page reserves. This check ensures that reservations are
 942	 * not "stolen". The child may still get SIGKILLed
 943	 */
 944	if (!vma_has_reserves(vma, chg) &&
 945			h->free_huge_pages - h->resv_huge_pages == 0)
 946		goto err;
 947
 948	/* If reserves cannot be used, ensure enough pages are in the pool */
 949	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
 950		goto err;
 951
 952	gfp_mask = htlb_alloc_mask(h);
 953	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
 954	page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
 
 
 
 
 
 
 
 
 
 
 955	if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
 956		SetPagePrivate(page);
 957		h->resv_huge_pages--;
 958	}
 959
 960	mpol_cond_put(mpol);
 961	return page;
 962
 963err:
 964	return NULL;
 965}
 966
 967/*
 968 * common helper functions for hstate_next_node_to_{alloc|free}.
 969 * We may have allocated or freed a huge page based on a different
 970 * nodes_allowed previously, so h->next_node_to_{alloc|free} might
 971 * be outside of *nodes_allowed.  Ensure that we use an allowed
 972 * node for alloc or free.
 973 */
 974static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
 975{
 976	nid = next_node_in(nid, *nodes_allowed);
 977	VM_BUG_ON(nid >= MAX_NUMNODES);
 978
 979	return nid;
 980}
 981
 982static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
 983{
 984	if (!node_isset(nid, *nodes_allowed))
 985		nid = next_node_allowed(nid, nodes_allowed);
 986	return nid;
 987}
 988
 989/*
 990 * returns the previously saved node ["this node"] from which to
 991 * allocate a persistent huge page for the pool and advance the
 992 * next node from which to allocate, handling wrap at end of node
 993 * mask.
 994 */
 995static int hstate_next_node_to_alloc(struct hstate *h,
 996					nodemask_t *nodes_allowed)
 997{
 998	int nid;
 999
1000	VM_BUG_ON(!nodes_allowed);
1001
1002	nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
1003	h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
1004
1005	return nid;
1006}
1007
1008/*
1009 * helper for free_pool_huge_page() - return the previously saved
1010 * node ["this node"] from which to free a huge page.  Advance the
1011 * next node id whether or not we find a free huge page to free so
1012 * that the next attempt to free addresses the next node.
1013 */
1014static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
1015{
1016	int nid;
1017
1018	VM_BUG_ON(!nodes_allowed);
1019
1020	nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
1021	h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
1022
1023	return nid;
1024}
1025
1026#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask)		\
1027	for (nr_nodes = nodes_weight(*mask);				\
1028		nr_nodes > 0 &&						\
1029		((node = hstate_next_node_to_alloc(hs, mask)) || 1);	\
1030		nr_nodes--)
1031
1032#define for_each_node_mask_to_free(hs, nr_nodes, node, mask)		\
1033	for (nr_nodes = nodes_weight(*mask);				\
1034		nr_nodes > 0 &&						\
1035		((node = hstate_next_node_to_free(hs, mask)) || 1);	\
1036		nr_nodes--)
1037
1038#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
1039static void destroy_compound_gigantic_page(struct page *page,
1040					unsigned int order)
1041{
1042	int i;
1043	int nr_pages = 1 << order;
1044	struct page *p = page + 1;
1045
1046	atomic_set(compound_mapcount_ptr(page), 0);
1047	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
 
 
 
 
 
1048		clear_compound_head(p);
1049		set_page_refcounted(p);
 
1050	}
1051
1052	set_compound_order(page, 0);
1053	__ClearPageHead(page);
1054}
1055
1056static void free_gigantic_page(struct page *page, unsigned int order)
 
1057{
1058	free_contig_range(page_to_pfn(page), 1 << order);
1059}
1060
1061static int __alloc_gigantic_page(unsigned long start_pfn,
1062				unsigned long nr_pages, gfp_t gfp_mask)
 
1063{
1064	unsigned long end_pfn = start_pfn + nr_pages;
1065	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
1066				  gfp_mask);
1067}
1068
1069static bool pfn_range_valid_gigantic(struct zone *z,
1070			unsigned long start_pfn, unsigned long nr_pages)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1071{
1072	unsigned long i, end_pfn = start_pfn + nr_pages;
1073	struct page *page;
 
 
 
1074
1075	for (i = start_pfn; i < end_pfn; i++) {
1076		if (!pfn_valid(i))
1077			return false;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1078
1079		page = pfn_to_page(i);
 
 
1080
1081		if (page_zone(page) != z)
1082			return false;
 
 
 
 
 
1083
1084		if (PageReserved(page))
1085			return false;
 
 
 
 
 
 
 
 
 
1086
1087		if (page_count(page) > 0)
1088			return false;
 
 
 
 
 
 
 
 
 
 
 
1089
1090		if (PageHuge(page))
1091			return false;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1092	}
1093
1094	return true;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1095}
1096
1097static bool zone_spans_last_pfn(const struct zone *zone,
1098			unsigned long start_pfn, unsigned long nr_pages)
1099{
1100	unsigned long last_pfn = start_pfn + nr_pages - 1;
1101	return zone_spans_pfn(zone, last_pfn);
1102}
1103
1104static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
1105		int nid, nodemask_t *nodemask)
1106{
1107	unsigned int order = huge_page_order(h);
1108	unsigned long nr_pages = 1 << order;
1109	unsigned long ret, pfn, flags;
1110	struct zonelist *zonelist;
1111	struct zone *zone;
1112	struct zoneref *z;
1113
1114	zonelist = node_zonelist(nid, gfp_mask);
1115	for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nodemask) {
1116		spin_lock_irqsave(&zone->lock, flags);
 
 
1117
1118		pfn = ALIGN(zone->zone_start_pfn, nr_pages);
1119		while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
1120			if (pfn_range_valid_gigantic(zone, pfn, nr_pages)) {
1121				/*
1122				 * We release the zone lock here because
1123				 * alloc_contig_range() will also lock the zone
1124				 * at some point. If there's an allocation
1125				 * spinning on this lock, it may win the race
1126				 * and cause alloc_contig_range() to fail...
1127				 */
1128				spin_unlock_irqrestore(&zone->lock, flags);
1129				ret = __alloc_gigantic_page(pfn, nr_pages, gfp_mask);
1130				if (!ret)
1131					return pfn_to_page(pfn);
1132				spin_lock_irqsave(&zone->lock, flags);
1133			}
1134			pfn += nr_pages;
1135		}
1136
1137		spin_unlock_irqrestore(&zone->lock, flags);
 
 
 
 
 
 
1138	}
1139
1140	return NULL;
1141}
 
 
 
 
 
1142
1143static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
1144static void prep_compound_gigantic_page(struct page *page, unsigned int order);
 
 
 
 
 
 
 
 
 
 
 
 
1145
1146#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
1147static inline bool gigantic_page_supported(void) { return false; }
1148static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
1149		int nid, nodemask_t *nodemask) { return NULL; }
1150static inline void free_gigantic_page(struct page *page, unsigned int order) { }
1151static inline void destroy_compound_gigantic_page(struct page *page,
1152						unsigned int order) { }
1153#endif
1154
1155static void update_and_free_page(struct hstate *h, struct page *page)
1156{
1157	int i;
 
 
1158
1159	if (hstate_is_gigantic(h) && !gigantic_page_supported())
1160		return;
1161
1162	h->nr_huge_pages--;
1163	h->nr_huge_pages_node[page_to_nid(page)]--;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1164	for (i = 0; i < pages_per_huge_page(h); i++) {
1165		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
 
1166				1 << PG_referenced | 1 << PG_dirty |
1167				1 << PG_active | 1 << PG_private |
1168				1 << PG_writeback);
1169	}
1170	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
1171	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
1172	set_page_refcounted(page);
1173	if (hstate_is_gigantic(h)) {
1174		destroy_compound_gigantic_page(page, huge_page_order(h));
1175		free_gigantic_page(page, huge_page_order(h));
 
 
 
1176	} else {
1177		__free_pages(page, huge_page_order(h));
1178	}
1179}
1180
1181struct hstate *size_to_hstate(unsigned long size)
1182{
1183	struct hstate *h;
1184
1185	for_each_hstate(h) {
1186		if (huge_page_size(h) == size)
1187			return h;
1188	}
1189	return NULL;
1190}
1191
1192/*
1193 * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
1194 * to hstate->hugepage_activelist.)
 
 
1195 *
1196 * This function can be called for tail pages, but never returns true for them.
 
 
 
1197 */
1198bool page_huge_active(struct page *page)
1199{
1200	VM_BUG_ON_PAGE(!PageHuge(page), page);
1201	return PageHead(page) && PagePrivate(&page[1]);
1202}
1203
1204/* never called for tail page */
1205static void set_page_huge_active(struct page *page)
1206{
1207	VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1208	SetPagePrivate(&page[1]);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1209}
 
1210
1211static void clear_page_huge_active(struct page *page)
1212{
1213	VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
1214	ClearPagePrivate(&page[1]);
1215}
1216
1217/*
1218 * Internal hugetlb specific page flag. Do not use outside of the hugetlb
1219 * code
1220 */
1221static inline bool PageHugeTemporary(struct page *page)
1222{
1223	if (!PageHuge(page))
1224		return false;
 
 
1225
1226	return (unsigned long)page[2].mapping == -1U;
 
 
 
 
 
 
 
 
1227}
1228
1229static inline void SetPageHugeTemporary(struct page *page)
1230{
1231	page[2].mapping = (void *)-1U;
 
 
 
 
 
 
 
1232}
1233
1234static inline void ClearPageHugeTemporary(struct page *page)
1235{
1236	page[2].mapping = NULL;
 
 
 
 
 
 
1237}
1238
1239void free_huge_page(struct page *page)
1240{
1241	/*
1242	 * Can't pass hstate in here because it is called from the
1243	 * compound page destructor.
1244	 */
1245	struct hstate *h = page_hstate(page);
1246	int nid = page_to_nid(page);
1247	struct hugepage_subpool *spool =
1248		(struct hugepage_subpool *)page_private(page);
1249	bool restore_reserve;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1250
1251	set_page_private(page, 0);
1252	page->mapping = NULL;
1253	VM_BUG_ON_PAGE(page_count(page), page);
1254	VM_BUG_ON_PAGE(page_mapcount(page), page);
1255	restore_reserve = PagePrivate(page);
1256	ClearPagePrivate(page);
1257
1258	/*
1259	 * A return code of zero implies that the subpool will be under its
1260	 * minimum size if the reservation is not restored after page is free.
1261	 * Therefore, force restore_reserve operation.
1262	 */
1263	if (hugepage_subpool_put_pages(spool, 1) == 0)
1264		restore_reserve = true;
1265
1266	spin_lock(&hugetlb_lock);
1267	clear_page_huge_active(page);
1268	hugetlb_cgroup_uncharge_page(hstate_index(h),
1269				     pages_per_huge_page(h), page);
1270	if (restore_reserve)
1271		h->resv_huge_pages++;
1272
1273	if (PageHugeTemporary(page)) {
1274		list_del(&page->lru);
1275		ClearPageHugeTemporary(page);
1276		update_and_free_page(h, page);
1277	} else if (h->surplus_huge_pages_node[nid]) {
1278		/* remove the page from active list */
1279		list_del(&page->lru);
1280		update_and_free_page(h, page);
1281		h->surplus_huge_pages--;
1282		h->surplus_huge_pages_node[nid]--;
1283	} else {
1284		arch_clear_hugepage_flags(page);
1285		enqueue_huge_page(h, page);
 
1286	}
1287	spin_unlock(&hugetlb_lock);
1288}
1289
1290static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
 
 
 
1291{
1292	INIT_LIST_HEAD(&page->lru);
1293	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
1294	spin_lock(&hugetlb_lock);
1295	set_hugetlb_cgroup(page, NULL);
1296	h->nr_huge_pages++;
1297	h->nr_huge_pages_node[nid]++;
1298	spin_unlock(&hugetlb_lock);
1299}
1300
1301static void prep_compound_gigantic_page(struct page *page, unsigned int order)
1302{
1303	int i;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1304	int nr_pages = 1 << order;
1305	struct page *p = page + 1;
 
 
 
 
 
 
 
1306
1307	/* we rely on prep_new_huge_page to set the destructor */
1308	set_compound_order(page, order);
1309	__ClearPageReserved(page);
1310	__SetPageHead(page);
1311	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
1312		/*
1313		 * For gigantic hugepages allocated through bootmem at
1314		 * boot, it's safer to be consistent with the not-gigantic
1315		 * hugepages and clear the PG_reserved bit from all tail pages
1316		 * too.  Otherwse drivers using get_user_pages() to access tail
1317		 * pages may get the reference counting wrong if they see
1318		 * PG_reserved set on a tail page (despite the head page not
1319		 * having PG_reserved set).  Enforcing this consistency between
1320		 * head and tail pages allows drivers to optimize away a check
1321		 * on the head page when they need know if put_page() is needed
1322		 * after get_user_pages().
1323		 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1324		__ClearPageReserved(p);
1325		set_page_count(p, 0);
1326		set_compound_head(p, page);
1327	}
1328	atomic_set(compound_mapcount_ptr(page), -1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1329}
1330
1331/*
1332 * PageHuge() only returns true for hugetlbfs pages, but not for normal or
1333 * transparent huge pages.  See the PageTransHuge() documentation for more
1334 * details.
1335 */
1336int PageHuge(struct page *page)
1337{
1338	if (!PageCompound(page))
1339		return 0;
1340
1341	page = compound_head(page);
1342	return page[1].compound_dtor == HUGETLB_PAGE_DTOR;
1343}
1344EXPORT_SYMBOL_GPL(PageHuge);
1345
1346/*
1347 * PageHeadHuge() only returns true for hugetlbfs head page, but not for
1348 * normal or transparent huge pages.
1349 */
1350int PageHeadHuge(struct page *page_head)
1351{
1352	if (!PageHead(page_head))
1353		return 0;
1354
1355	return get_compound_page_dtor(page_head) == free_huge_page;
1356}
 
1357
1358pgoff_t __basepage_index(struct page *page)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1359{
1360	struct page *page_head = compound_head(page);
1361	pgoff_t index = page_index(page_head);
1362	unsigned long compound_idx;
1363
1364	if (!PageHuge(page_head))
1365		return page_index(page);
1366
1367	if (compound_order(page_head) >= MAX_ORDER)
1368		compound_idx = page_to_pfn(page) - page_to_pfn(page_head);
1369	else
1370		compound_idx = page - page_head;
1371
1372	return (index << compound_order(page_head)) + compound_idx;
1373}
1374
1375static struct page *alloc_buddy_huge_page(struct hstate *h,
1376		gfp_t gfp_mask, int nid, nodemask_t *nmask)
 
1377{
1378	int order = huge_page_order(h);
1379	struct page *page;
 
 
1380
1381	gfp_mask |= __GFP_COMP|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
 
 
 
 
 
 
 
 
 
 
 
1382	if (nid == NUMA_NO_NODE)
1383		nid = numa_mem_id();
1384	page = __alloc_pages_nodemask(gfp_mask, order, nid, nmask);
1385	if (page)
1386		__count_vm_event(HTLB_BUDDY_PGALLOC);
1387	else
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1388		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 
 
1389
1390	return page;
 
1391}
1392
1393/*
1394 * Common helper to allocate a fresh hugetlb page. All specific allocators
1395 * should use this function to get new hugetlb pages
 
 
 
1396 */
1397static struct page *alloc_fresh_huge_page(struct hstate *h,
1398		gfp_t gfp_mask, int nid, nodemask_t *nmask)
 
1399{
1400	struct page *page;
 
1401
 
1402	if (hstate_is_gigantic(h))
1403		page = alloc_gigantic_page(h, gfp_mask, nid, nmask);
1404	else
1405		page = alloc_buddy_huge_page(h, gfp_mask,
1406				nid, nmask);
1407	if (!page)
1408		return NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1409
1410	if (hstate_is_gigantic(h))
1411		prep_compound_gigantic_page(page, huge_page_order(h));
1412	prep_new_huge_page(h, page, page_to_nid(page));
1413
1414	return page;
1415}
1416
1417/*
1418 * Allocates a fresh page to the hugetlb allocator pool in the node interleaved
1419 * manner.
1420 */
1421static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
 
1422{
1423	struct page *page;
1424	int nr_nodes, node;
1425	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
1426
1427	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
1428		page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed);
1429		if (page)
1430			break;
 
 
 
1431	}
1432
1433	if (!page)
1434		return 0;
1435
1436	put_page(page); /* free it into the hugepage allocator */
1437
1438	return 1;
1439}
1440
1441/*
1442 * Free huge page from pool from next node to free.
1443 * Attempt to keep persistent huge pages more or less
1444 * balanced over allowed nodes.
 
1445 * Called with hugetlb_lock locked.
1446 */
1447static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
1448							 bool acct_surplus)
 
1449{
1450	int nr_nodes, node;
1451	int ret = 0;
 
1452
 
1453	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
1454		/*
1455		 * If we're returning unused surplus pages, only examine
1456		 * nodes with surplus pages.
1457		 */
1458		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
1459		    !list_empty(&h->hugepage_freelists[node])) {
1460			struct page *page =
1461				list_entry(h->hugepage_freelists[node].next,
1462					  struct page, lru);
1463			list_del(&page->lru);
1464			h->free_huge_pages--;
1465			h->free_huge_pages_node[node]--;
1466			if (acct_surplus) {
1467				h->surplus_huge_pages--;
1468				h->surplus_huge_pages_node[node]--;
1469			}
1470			update_and_free_page(h, page);
1471			ret = 1;
1472			break;
1473		}
1474	}
1475
1476	return ret;
1477}
1478
1479/*
1480 * Dissolve a given free hugepage into free buddy pages. This function does
1481 * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
1482 * number of free hugepages would be reduced below the number of reserved
1483 * hugepages.
 
 
 
 
 
 
 
 
1484 */
1485int dissolve_free_huge_page(struct page *page)
1486{
1487	int rc = 0;
 
 
 
 
 
 
1488
1489	spin_lock(&hugetlb_lock);
1490	if (PageHuge(page) && !page_count(page)) {
1491		struct page *head = compound_head(page);
1492		struct hstate *h = page_hstate(head);
1493		int nid = page_to_nid(head);
1494		if (h->free_huge_pages - h->resv_huge_pages == 0) {
1495			rc = -EBUSY;
 
 
1496			goto out;
1497		}
1498		/*
1499		 * Move PageHWPoison flag from head page to the raw error page,
1500		 * which makes any subpages rather than the error page reusable.
1501		 */
1502		if (PageHWPoison(head) && page != head) {
1503			SetPageHWPoison(page);
1504			ClearPageHWPoison(head);
 
 
 
 
 
 
 
 
 
 
1505		}
1506		list_del(&head->lru);
1507		h->free_huge_pages--;
1508		h->free_huge_pages_node[nid]--;
1509		h->max_huge_pages--;
1510		update_and_free_page(h, head);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1511	}
1512out:
1513	spin_unlock(&hugetlb_lock);
1514	return rc;
1515}
1516
1517/*
1518 * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
1519 * make specified memory blocks removable from the system.
1520 * Note that this will dissolve a free gigantic hugepage completely, if any
1521 * part of it lies within the given range.
1522 * Also note that if dissolve_free_huge_page() returns with an error, all
1523 * free hugepages that were dissolved before that error are lost.
1524 */
1525int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1526{
1527	unsigned long pfn;
1528	struct page *page;
1529	int rc = 0;
 
 
1530
1531	if (!hugepages_supported())
1532		return rc;
1533
1534	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
 
 
 
 
1535		page = pfn_to_page(pfn);
1536		if (PageHuge(page) && !page_count(page)) {
1537			rc = dissolve_free_huge_page(page);
1538			if (rc)
1539				break;
1540		}
1541	}
1542
1543	return rc;
1544}
1545
1546/*
1547 * Allocates a fresh surplus page from the page allocator.
1548 */
1549static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
1550		int nid, nodemask_t *nmask)
1551{
1552	struct page *page = NULL;
1553
1554	if (hstate_is_gigantic(h))
1555		return NULL;
1556
1557	spin_lock(&hugetlb_lock);
1558	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages)
1559		goto out_unlock;
1560	spin_unlock(&hugetlb_lock);
1561
1562	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask);
1563	if (!page)
1564		return NULL;
1565
1566	spin_lock(&hugetlb_lock);
1567	/*
1568	 * We could have raced with the pool size change.
1569	 * Double check that and simply deallocate the new page
1570	 * if we would end up overcommiting the surpluses. Abuse
1571	 * temporary page to workaround the nasty free_huge_page
1572	 * codeflow
1573	 */
1574	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
1575		SetPageHugeTemporary(page);
1576		put_page(page);
1577		page = NULL;
1578	} else {
1579		h->surplus_huge_pages++;
1580		h->surplus_huge_pages_node[page_to_nid(page)]++;
1581	}
1582
 
 
 
1583out_unlock:
1584	spin_unlock(&hugetlb_lock);
1585
1586	return page;
1587}
1588
1589static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
1590		int nid, nodemask_t *nmask)
1591{
1592	struct page *page;
1593
1594	if (hstate_is_gigantic(h))
1595		return NULL;
1596
1597	page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask);
1598	if (!page)
1599		return NULL;
1600
 
 
1601	/*
1602	 * We do not account these pages as surplus because they are only
1603	 * temporary and will be released properly on the last reference
1604	 */
1605	SetPageHugeTemporary(page);
1606
1607	return page;
1608}
1609
1610/*
1611 * Use the VMA's mpolicy to allocate a huge page from the buddy.
1612 */
1613static
1614struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
1615		struct vm_area_struct *vma, unsigned long addr)
1616{
1617	struct page *page;
1618	struct mempolicy *mpol;
1619	gfp_t gfp_mask = htlb_alloc_mask(h);
1620	int nid;
1621	nodemask_t *nodemask;
1622
1623	nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
1624	page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask);
1625	mpol_cond_put(mpol);
1626
1627	return page;
1628}
1629
1630/* page migration callback function */
1631struct page *alloc_huge_page_node(struct hstate *h, int nid)
1632{
1633	gfp_t gfp_mask = htlb_alloc_mask(h);
1634	struct page *page = NULL;
1635
1636	if (nid != NUMA_NO_NODE)
1637		gfp_mask |= __GFP_THISNODE;
1638
1639	spin_lock(&hugetlb_lock);
1640	if (h->free_huge_pages - h->resv_huge_pages > 0)
1641		page = dequeue_huge_page_nodemask(h, gfp_mask, nid, NULL);
1642	spin_unlock(&hugetlb_lock);
1643
1644	if (!page)
1645		page = alloc_migrate_huge_page(h, gfp_mask, nid, NULL);
1646
1647	return page;
1648}
1649
1650/* page migration callback function */
1651struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
1652		nodemask_t *nmask)
1653{
1654	gfp_t gfp_mask = htlb_alloc_mask(h);
1655
1656	spin_lock(&hugetlb_lock);
1657	if (h->free_huge_pages - h->resv_huge_pages > 0) {
1658		struct page *page;
1659
1660		page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
1661		if (page) {
1662			spin_unlock(&hugetlb_lock);
1663			return page;
1664		}
1665	}
1666	spin_unlock(&hugetlb_lock);
1667
1668	return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask);
1669}
1670
1671/* mempolicy aware migration callback */
1672struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
1673		unsigned long address)
1674{
1675	struct mempolicy *mpol;
1676	nodemask_t *nodemask;
1677	struct page *page;
1678	gfp_t gfp_mask;
1679	int node;
1680
1681	gfp_mask = htlb_alloc_mask(h);
1682	node = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
1683	page = alloc_huge_page_nodemask(h, node, nodemask);
1684	mpol_cond_put(mpol);
1685
1686	return page;
1687}
1688
1689/*
1690 * Increase the hugetlb pool such that it can accommodate a reservation
1691 * of size 'delta'.
1692 */
1693static int gather_surplus_pages(struct hstate *h, int delta)
 
1694{
1695	struct list_head surplus_list;
1696	struct page *page, *tmp;
1697	int ret, i;
1698	int needed, allocated;
 
1699	bool alloc_ok = true;
1700
 
1701	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
1702	if (needed <= 0) {
1703		h->resv_huge_pages += delta;
1704		return 0;
1705	}
1706
1707	allocated = 0;
1708	INIT_LIST_HEAD(&surplus_list);
1709
1710	ret = -ENOMEM;
1711retry:
1712	spin_unlock(&hugetlb_lock);
1713	for (i = 0; i < needed; i++) {
1714		page = alloc_surplus_huge_page(h, htlb_alloc_mask(h),
1715				NUMA_NO_NODE, NULL);
1716		if (!page) {
1717			alloc_ok = false;
1718			break;
1719		}
1720		list_add(&page->lru, &surplus_list);
1721		cond_resched();
1722	}
1723	allocated += i;
1724
1725	/*
1726	 * After retaking hugetlb_lock, we need to recalculate 'needed'
1727	 * because either resv_huge_pages or free_huge_pages may have changed.
1728	 */
1729	spin_lock(&hugetlb_lock);
1730	needed = (h->resv_huge_pages + delta) -
1731			(h->free_huge_pages + allocated);
1732	if (needed > 0) {
1733		if (alloc_ok)
1734			goto retry;
1735		/*
1736		 * We were not able to allocate enough pages to
1737		 * satisfy the entire reservation so we free what
1738		 * we've allocated so far.
1739		 */
1740		goto free;
1741	}
1742	/*
1743	 * The surplus_list now contains _at_least_ the number of extra pages
1744	 * needed to accommodate the reservation.  Add the appropriate number
1745	 * of pages to the hugetlb pool and free the extras back to the buddy
1746	 * allocator.  Commit the entire reservation here to prevent another
1747	 * process from stealing the pages as they are added to the pool but
1748	 * before they are reserved.
1749	 */
1750	needed += allocated;
1751	h->resv_huge_pages += delta;
1752	ret = 0;
1753
1754	/* Free the needed pages to the hugetlb pool */
1755	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
1756		if ((--needed) < 0)
1757			break;
1758		/*
1759		 * This page is now managed by the hugetlb allocator and has
1760		 * no users -- drop the buddy allocator's reference.
1761		 */
1762		put_page_testzero(page);
1763		VM_BUG_ON_PAGE(page_count(page), page);
1764		enqueue_huge_page(h, page);
1765	}
1766free:
1767	spin_unlock(&hugetlb_lock);
1768
1769	/* Free unnecessary surplus pages to the buddy allocator */
 
 
 
1770	list_for_each_entry_safe(page, tmp, &surplus_list, lru)
1771		put_page(page);
1772	spin_lock(&hugetlb_lock);
1773
1774	return ret;
1775}
1776
1777/*
1778 * This routine has two main purposes:
1779 * 1) Decrement the reservation count (resv_huge_pages) by the value passed
1780 *    in unused_resv_pages.  This corresponds to the prior adjustments made
1781 *    to the associated reservation map.
1782 * 2) Free any unused surplus pages that may have been allocated to satisfy
1783 *    the reservation.  As many as unused_resv_pages may be freed.
1784 *
1785 * Called with hugetlb_lock held.  However, the lock could be dropped (and
1786 * reacquired) during calls to cond_resched_lock.  Whenever dropping the lock,
1787 * we must make sure nobody else can claim pages we are in the process of
1788 * freeing.  Do this by ensuring resv_huge_page always is greater than the
1789 * number of huge pages we plan to free when dropping the lock.
1790 */
1791static void return_unused_surplus_pages(struct hstate *h,
1792					unsigned long unused_resv_pages)
1793{
1794	unsigned long nr_pages;
 
 
1795
1796	/* Cannot return gigantic pages currently */
1797	if (hstate_is_gigantic(h))
 
 
 
1798		goto out;
1799
1800	/*
1801	 * Part (or even all) of the reservation could have been backed
1802	 * by pre-allocated pages. Only free surplus pages.
1803	 */
1804	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
1805
1806	/*
1807	 * We want to release as many surplus pages as possible, spread
1808	 * evenly across all nodes with memory. Iterate across these nodes
1809	 * until we can no longer free unreserved surplus pages. This occurs
1810	 * when the nodes with surplus pages have no free pages.
1811	 * free_pool_huge_page() will balance the the freed pages across the
1812	 * on-line nodes with memory and will handle the hstate accounting.
1813	 *
1814	 * Note that we decrement resv_huge_pages as we free the pages.  If
1815	 * we drop the lock, resv_huge_pages will still be sufficiently large
1816	 * to cover subsequent pages we may free.
1817	 */
1818	while (nr_pages--) {
1819		h->resv_huge_pages--;
1820		unused_resv_pages--;
1821		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
1822			goto out;
1823		cond_resched_lock(&hugetlb_lock);
 
1824	}
1825
1826out:
1827	/* Fully uncommit the reservation */
1828	h->resv_huge_pages -= unused_resv_pages;
 
1829}
1830
1831
1832/*
1833 * vma_needs_reservation, vma_commit_reservation and vma_end_reservation
1834 * are used by the huge page allocation routines to manage reservations.
1835 *
1836 * vma_needs_reservation is called to determine if the huge page at addr
1837 * within the vma has an associated reservation.  If a reservation is
1838 * needed, the value 1 is returned.  The caller is then responsible for
1839 * managing the global reservation and subpool usage counts.  After
1840 * the huge page has been allocated, vma_commit_reservation is called
1841 * to add the page to the reservation map.  If the page allocation fails,
1842 * the reservation must be ended instead of committed.  vma_end_reservation
1843 * is called in such cases.
1844 *
1845 * In the normal case, vma_commit_reservation returns the same value
1846 * as the preceding vma_needs_reservation call.  The only time this
1847 * is not the case is if a reserve map was changed between calls.  It
1848 * is the responsibility of the caller to notice the difference and
1849 * take appropriate action.
1850 *
1851 * vma_add_reservation is used in error paths where a reservation must
1852 * be restored when a newly allocated huge page must be freed.  It is
1853 * to be called after calling vma_needs_reservation to determine if a
1854 * reservation exists.
 
 
 
 
 
1855 */
1856enum vma_resv_mode {
1857	VMA_NEEDS_RESV,
1858	VMA_COMMIT_RESV,
1859	VMA_END_RESV,
1860	VMA_ADD_RESV,
 
1861};
1862static long __vma_reservation_common(struct hstate *h,
1863				struct vm_area_struct *vma, unsigned long addr,
1864				enum vma_resv_mode mode)
1865{
1866	struct resv_map *resv;
1867	pgoff_t idx;
1868	long ret;
 
1869
1870	resv = vma_resv_map(vma);
1871	if (!resv)
1872		return 1;
1873
1874	idx = vma_hugecache_offset(h, vma, addr);
1875	switch (mode) {
1876	case VMA_NEEDS_RESV:
1877		ret = region_chg(resv, idx, idx + 1);
 
 
 
 
 
1878		break;
1879	case VMA_COMMIT_RESV:
1880		ret = region_add(resv, idx, idx + 1);
 
 
1881		break;
1882	case VMA_END_RESV:
1883		region_abort(resv, idx, idx + 1);
1884		ret = 0;
1885		break;
1886	case VMA_ADD_RESV:
1887		if (vma->vm_flags & VM_MAYSHARE)
1888			ret = region_add(resv, idx, idx + 1);
1889		else {
1890			region_abort(resv, idx, idx + 1);
 
 
 
 
 
 
 
 
1891			ret = region_del(resv, idx, idx + 1);
 
 
 
 
1892		}
1893		break;
1894	default:
1895		BUG();
1896	}
1897
1898	if (vma->vm_flags & VM_MAYSHARE)
1899		return ret;
1900	else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && ret >= 0) {
1901		/*
1902		 * In most cases, reserves always exist for private mappings.
1903		 * However, a file associated with mapping could have been
1904		 * hole punched or truncated after reserves were consumed.
1905		 * As subsequent fault on such a range will not use reserves.
1906		 * Subtle - The reserve map for private mappings has the
1907		 * opposite meaning than that of shared mappings.  If NO
1908		 * entry is in the reserve map, it means a reservation exists.
1909		 * If an entry exists in the reserve map, it means the
1910		 * reservation has already been consumed.  As a result, the
1911		 * return value of this routine is the opposite of the
1912		 * value returned from reserve map manipulation routines above.
1913		 */
1914		if (ret)
1915			return 0;
1916		else
1917			return 1;
1918	}
1919	else
1920		return ret < 0 ? ret : 0;
1921}
1922
1923static long vma_needs_reservation(struct hstate *h,
1924			struct vm_area_struct *vma, unsigned long addr)
1925{
1926	return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV);
1927}
1928
1929static long vma_commit_reservation(struct hstate *h,
1930			struct vm_area_struct *vma, unsigned long addr)
1931{
1932	return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV);
1933}
1934
1935static void vma_end_reservation(struct hstate *h,
1936			struct vm_area_struct *vma, unsigned long addr)
1937{
1938	(void)__vma_reservation_common(h, vma, addr, VMA_END_RESV);
1939}
1940
1941static long vma_add_reservation(struct hstate *h,
1942			struct vm_area_struct *vma, unsigned long addr)
1943{
1944	return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV);
1945}
1946
 
 
 
 
 
 
1947/*
1948 * This routine is called to restore a reservation on error paths.  In the
1949 * specific error paths, a huge page was allocated (via alloc_huge_page)
1950 * and is about to be freed.  If a reservation for the page existed,
1951 * alloc_huge_page would have consumed the reservation and set PagePrivate
1952 * in the newly allocated page.  When the page is freed via free_huge_page,
1953 * the global reservation count will be incremented if PagePrivate is set.
1954 * However, free_huge_page can not adjust the reserve map.  Adjust the
1955 * reserve map here to be consistent with global reserve count adjustments
1956 * to be made by free_huge_page.
1957 */
1958static void restore_reserve_on_error(struct hstate *h,
1959			struct vm_area_struct *vma, unsigned long address,
1960			struct page *page)
 
 
 
 
 
 
 
 
1961{
1962	if (unlikely(PagePrivate(page))) {
1963		long rc = vma_needs_reservation(h, vma, address);
1964
1965		if (unlikely(rc < 0)) {
 
1966			/*
1967			 * Rare out of memory condition in reserve map
1968			 * manipulation.  Clear PagePrivate so that
1969			 * global reserve count will not be incremented
1970			 * by free_huge_page.  This will make it appear
1971			 * as though the reservation for this page was
1972			 * consumed.  This may prevent the task from
1973			 * faulting in the page at a later time.  This
1974			 * is better than inconsistent global huge page
1975			 * accounting of reserve counts.
1976			 */
1977			ClearPagePrivate(page);
1978		} else if (rc) {
1979			rc = vma_add_reservation(h, vma, address);
1980			if (unlikely(rc < 0))
 
 
 
 
 
 
 
 
 
 
 
 
 
1981				/*
1982				 * See above comment about rare out of
1983				 * memory condition.
 
 
 
 
1984				 */
1985				ClearPagePrivate(page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1986		} else
1987			vma_end_reservation(h, vma, address);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1988	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1989}
1990
1991struct page *alloc_huge_page(struct vm_area_struct *vma,
1992				    unsigned long addr, int avoid_reserve)
1993{
1994	struct hugepage_subpool *spool = subpool_vma(vma);
1995	struct hstate *h = hstate_vma(vma);
1996	struct page *page;
 
1997	long map_chg, map_commit;
1998	long gbl_chg;
1999	int ret, idx;
2000	struct hugetlb_cgroup *h_cg;
 
2001
2002	idx = hstate_index(h);
2003	/*
2004	 * Examine the region/reserve map to determine if the process
2005	 * has a reservation for the page to be allocated.  A return
2006	 * code of zero indicates a reservation exists (no change).
2007	 */
2008	map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
2009	if (map_chg < 0)
2010		return ERR_PTR(-ENOMEM);
2011
2012	/*
2013	 * Processes that did not create the mapping will have no
2014	 * reserves as indicated by the region/reserve map. Check
2015	 * that the allocation will not exceed the subpool limit.
2016	 * Allocations for MAP_NORESERVE mappings also need to be
2017	 * checked against any subpool limit.
2018	 */
2019	if (map_chg || avoid_reserve) {
2020		gbl_chg = hugepage_subpool_get_pages(spool, 1);
2021		if (gbl_chg < 0) {
2022			vma_end_reservation(h, vma, addr);
2023			return ERR_PTR(-ENOSPC);
2024		}
2025
2026		/*
2027		 * Even though there was no reservation in the region/reserve
2028		 * map, there could be reservations associated with the
2029		 * subpool that can be used.  This would be indicated if the
2030		 * return value of hugepage_subpool_get_pages() is zero.
2031		 * However, if avoid_reserve is specified we still avoid even
2032		 * the subpool reservations.
2033		 */
2034		if (avoid_reserve)
2035			gbl_chg = 1;
2036	}
2037
 
 
 
 
 
 
 
 
 
 
2038	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
2039	if (ret)
2040		goto out_subpool_put;
2041
2042	spin_lock(&hugetlb_lock);
2043	/*
2044	 * glb_chg is passed to indicate whether or not a page must be taken
2045	 * from the global free pool (global change).  gbl_chg == 0 indicates
2046	 * a reservation exists for the allocation.
2047	 */
2048	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
2049	if (!page) {
2050		spin_unlock(&hugetlb_lock);
2051		page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
2052		if (!page)
2053			goto out_uncharge_cgroup;
 
2054		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
2055			SetPagePrivate(page);
2056			h->resv_huge_pages--;
2057		}
2058		spin_lock(&hugetlb_lock);
2059		list_move(&page->lru, &h->hugepage_activelist);
2060		/* Fall through */
2061	}
 
2062	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
2063	spin_unlock(&hugetlb_lock);
 
 
 
 
 
 
 
 
2064
2065	set_page_private(page, (unsigned long)spool);
2066
2067	map_commit = vma_commit_reservation(h, vma, addr);
2068	if (unlikely(map_chg > map_commit)) {
2069		/*
2070		 * The page was added to the reservation map between
2071		 * vma_needs_reservation and vma_commit_reservation.
2072		 * This indicates a race with hugetlb_reserve_pages.
2073		 * Adjust for the subpool count incremented above AND
2074		 * in hugetlb_reserve_pages for the same page.  Also,
2075		 * the reservation count added in hugetlb_reserve_pages
2076		 * no longer applies.
2077		 */
2078		long rsv_adjust;
2079
2080		rsv_adjust = hugepage_subpool_put_pages(spool, 1);
2081		hugetlb_acct_memory(h, -rsv_adjust);
 
 
 
2082	}
2083	return page;
2084
2085out_uncharge_cgroup:
2086	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
 
 
 
 
2087out_subpool_put:
2088	if (map_chg || avoid_reserve)
2089		hugepage_subpool_put_pages(spool, 1);
2090	vma_end_reservation(h, vma, addr);
2091	return ERR_PTR(-ENOSPC);
2092}
2093
2094int alloc_bootmem_huge_page(struct hstate *h)
2095	__attribute__ ((weak, alias("__alloc_bootmem_huge_page")));
2096int __alloc_bootmem_huge_page(struct hstate *h)
2097{
2098	struct huge_bootmem_page *m;
2099	int nr_nodes, node;
2100
 
 
 
 
 
 
 
 
 
2101	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
2102		void *addr;
2103
2104		addr = memblock_virt_alloc_try_nid_nopanic(
2105				huge_page_size(h), huge_page_size(h),
2106				0, BOOTMEM_ALLOC_ACCESSIBLE, node);
2107		if (addr) {
2108			/*
2109			 * Use the beginning of the huge page to store the
2110			 * huge_bootmem_page struct (until gather_bootmem
2111			 * puts them into the mem_map).
2112			 */
2113			m = addr;
2114			goto found;
2115		}
2116	}
2117	return 0;
2118
2119found:
2120	BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
2121	/* Put them into a private list first because mem_map is not up yet */
 
2122	list_add(&m->list, &huge_boot_pages);
2123	m->hstate = h;
2124	return 1;
2125}
2126
2127static void __init prep_compound_huge_page(struct page *page,
2128		unsigned int order)
2129{
2130	if (unlikely(order > (MAX_ORDER - 1)))
2131		prep_compound_gigantic_page(page, order);
2132	else
2133		prep_compound_page(page, order);
2134}
2135
2136/* Put bootmem huge pages into the standard lists after mem_map is up */
2137static void __init gather_bootmem_prealloc(void)
2138{
2139	struct huge_bootmem_page *m;
2140
2141	list_for_each_entry(m, &huge_boot_pages, list) {
 
 
2142		struct hstate *h = m->hstate;
2143		struct page *page;
2144
2145#ifdef CONFIG_HIGHMEM
2146		page = pfn_to_page(m->phys >> PAGE_SHIFT);
2147		memblock_free_late(__pa(m),
2148				   sizeof(struct huge_bootmem_page));
2149#else
2150		page = virt_to_page(m);
2151#endif
2152		WARN_ON(page_count(page) != 1);
2153		prep_compound_huge_page(page, h->order);
2154		WARN_ON(PageReserved(page));
2155		prep_new_huge_page(h, page, page_to_nid(page));
2156		put_page(page); /* free it into the hugepage allocator */
2157
2158		/*
2159		 * If we had gigantic hugepages allocated at boot time, we need
2160		 * to restore the 'stolen' pages to totalram_pages in order to
2161		 * fix confusing memory reports from free(1) and another
2162		 * side-effects, like CommitLimit going negative.
2163		 */
2164		if (hstate_is_gigantic(h))
2165			adjust_managed_page_count(page, 1 << h->order);
2166	}
2167}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2168
2169static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
2170{
2171	unsigned long i;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2172
2173	for (i = 0; i < h->max_huge_pages; ++i) {
2174		if (hstate_is_gigantic(h)) {
2175			if (!alloc_bootmem_huge_page(h))
2176				break;
2177		} else if (!alloc_pool_huge_page(h,
2178					 &node_states[N_MEMORY]))
 
2179			break;
2180		cond_resched();
2181	}
2182	if (i < h->max_huge_pages) {
2183		char buf[32];
2184
2185		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2186		pr_warn("HugeTLB: allocating %lu of page size %s failed.  Only allocated %lu hugepages.\n",
2187			h->max_huge_pages, buf, i);
2188		h->max_huge_pages = i;
2189	}
 
2190}
2191
2192static void __init hugetlb_init_hstates(void)
2193{
2194	struct hstate *h;
2195
2196	for_each_hstate(h) {
2197		if (minimum_order > huge_page_order(h))
2198			minimum_order = huge_page_order(h);
2199
2200		/* oversize hugepages were init'ed in early boot */
2201		if (!hstate_is_gigantic(h))
2202			hugetlb_hstate_alloc_pages(h);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2203	}
2204	VM_BUG_ON(minimum_order == UINT_MAX);
2205}
2206
2207static void __init report_hugepages(void)
2208{
2209	struct hstate *h;
2210
2211	for_each_hstate(h) {
2212		char buf[32];
2213
2214		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
2215		pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n",
2216			buf, h->free_huge_pages);
 
 
2217	}
2218}
2219
2220#ifdef CONFIG_HIGHMEM
2221static void try_to_free_low(struct hstate *h, unsigned long count,
2222						nodemask_t *nodes_allowed)
2223{
2224	int i;
 
2225
 
2226	if (hstate_is_gigantic(h))
2227		return;
2228
 
 
 
2229	for_each_node_mask(i, *nodes_allowed) {
2230		struct page *page, *next;
2231		struct list_head *freel = &h->hugepage_freelists[i];
2232		list_for_each_entry_safe(page, next, freel, lru) {
2233			if (count >= h->nr_huge_pages)
2234				return;
2235			if (PageHighMem(page))
2236				continue;
2237			list_del(&page->lru);
2238			update_and_free_page(h, page);
2239			h->free_huge_pages--;
2240			h->free_huge_pages_node[page_to_nid(page)]--;
2241		}
2242	}
 
 
 
 
 
2243}
2244#else
2245static inline void try_to_free_low(struct hstate *h, unsigned long count,
2246						nodemask_t *nodes_allowed)
2247{
2248}
2249#endif
2250
2251/*
2252 * Increment or decrement surplus_huge_pages.  Keep node-specific counters
2253 * balanced by operating on them in a round-robin fashion.
2254 * Returns 1 if an adjustment was made.
2255 */
2256static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
2257				int delta)
2258{
2259	int nr_nodes, node;
2260
 
2261	VM_BUG_ON(delta != -1 && delta != 1);
2262
2263	if (delta < 0) {
2264		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
2265			if (h->surplus_huge_pages_node[node])
2266				goto found;
2267		}
2268	} else {
2269		for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
2270			if (h->surplus_huge_pages_node[node] <
2271					h->nr_huge_pages_node[node])
2272				goto found;
2273		}
2274	}
2275	return 0;
2276
2277found:
2278	h->surplus_huge_pages += delta;
2279	h->surplus_huge_pages_node[node] += delta;
2280	return 1;
2281}
2282
2283#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
2284static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
2285						nodemask_t *nodes_allowed)
2286{
2287	unsigned long min_count, ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2288
2289	if (hstate_is_gigantic(h) && !gigantic_page_supported())
2290		return h->max_huge_pages;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2291
2292	/*
2293	 * Increase the pool size
2294	 * First take pages out of surplus state.  Then make up the
2295	 * remaining difference by allocating fresh huge pages.
2296	 *
2297	 * We might race with alloc_surplus_huge_page() here and be unable
2298	 * to convert a surplus huge page to a normal huge page. That is
2299	 * not critical, though, it just means the overall size of the
2300	 * pool might be one hugepage larger than it needs to be, but
2301	 * within all the constraints specified by the sysctls.
2302	 */
2303	spin_lock(&hugetlb_lock);
2304	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
2305		if (!adjust_pool_surplus(h, nodes_allowed, -1))
2306			break;
2307	}
2308
2309	while (count > persistent_huge_pages(h)) {
2310		/*
2311		 * If this allocation races such that we no longer need the
2312		 * page, free_huge_page will handle it by freeing the page
2313		 * and reducing the surplus.
2314		 */
2315		spin_unlock(&hugetlb_lock);
2316
2317		/* yield cpu to avoid soft lockup */
2318		cond_resched();
2319
2320		ret = alloc_pool_huge_page(h, nodes_allowed);
2321		spin_lock(&hugetlb_lock);
 
2322		if (!ret)
2323			goto out;
2324
2325		/* Bail for signals. Probably ctrl-c from user */
2326		if (signal_pending(current))
2327			goto out;
2328	}
2329
2330	/*
2331	 * Decrease the pool size
2332	 * First return free pages to the buddy allocator (being careful
2333	 * to keep enough around to satisfy reservations).  Then place
2334	 * pages into surplus state as needed so the pool will shrink
2335	 * to the desired size as pages become free.
2336	 *
2337	 * By placing pages into the surplus state independent of the
2338	 * overcommit value, we are allowing the surplus pool size to
2339	 * exceed overcommit. There are few sane options here. Since
2340	 * alloc_surplus_huge_page() is checking the global counter,
2341	 * though, we'll note that we're not allowed to exceed surplus
2342	 * and won't grow the pool anywhere else. Not until one of the
2343	 * sysctls are changed, or the surplus pages go out of use.
2344	 */
2345	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
2346	min_count = max(count, min_count);
2347	try_to_free_low(h, min_count, nodes_allowed);
 
 
 
 
2348	while (min_count < persistent_huge_pages(h)) {
2349		if (!free_pool_huge_page(h, nodes_allowed, 0))
 
2350			break;
2351		cond_resched_lock(&hugetlb_lock);
 
2352	}
 
 
 
 
 
 
2353	while (count < persistent_huge_pages(h)) {
2354		if (!adjust_pool_surplus(h, nodes_allowed, 1))
2355			break;
2356	}
2357out:
2358	ret = persistent_huge_pages(h);
2359	spin_unlock(&hugetlb_lock);
2360	return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2361}
2362
2363#define HSTATE_ATTR_RO(_name) \
2364	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
2365
 
 
 
2366#define HSTATE_ATTR(_name) \
2367	static struct kobj_attribute _name##_attr = \
2368		__ATTR(_name, 0644, _name##_show, _name##_store)
2369
2370static struct kobject *hugepages_kobj;
2371static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
2372
2373static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
2374
2375static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
2376{
2377	int i;
2378
2379	for (i = 0; i < HUGE_MAX_HSTATE; i++)
2380		if (hstate_kobjs[i] == kobj) {
2381			if (nidp)
2382				*nidp = NUMA_NO_NODE;
2383			return &hstates[i];
2384		}
2385
2386	return kobj_to_node_hstate(kobj, nidp);
2387}
2388
2389static ssize_t nr_hugepages_show_common(struct kobject *kobj,
2390					struct kobj_attribute *attr, char *buf)
2391{
2392	struct hstate *h;
2393	unsigned long nr_huge_pages;
2394	int nid;
2395
2396	h = kobj_to_hstate(kobj, &nid);
2397	if (nid == NUMA_NO_NODE)
2398		nr_huge_pages = h->nr_huge_pages;
2399	else
2400		nr_huge_pages = h->nr_huge_pages_node[nid];
2401
2402	return sprintf(buf, "%lu\n", nr_huge_pages);
2403}
2404
2405static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
2406					   struct hstate *h, int nid,
2407					   unsigned long count, size_t len)
2408{
2409	int err;
2410	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
2411
2412	if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
2413		err = -EINVAL;
2414		goto out;
2415	}
2416
2417	if (nid == NUMA_NO_NODE) {
2418		/*
2419		 * global hstate attribute
2420		 */
2421		if (!(obey_mempolicy &&
2422				init_nodemask_of_mempolicy(nodes_allowed))) {
2423			NODEMASK_FREE(nodes_allowed);
2424			nodes_allowed = &node_states[N_MEMORY];
2425		}
2426	} else if (nodes_allowed) {
2427		/*
2428		 * per node hstate attribute: adjust count to global,
2429		 * but restrict alloc/free to the specified node.
2430		 */
2431		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
2432		init_nodemask_of_node(nodes_allowed, nid);
2433	} else
2434		nodes_allowed = &node_states[N_MEMORY];
2435
2436	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
2437
2438	if (nodes_allowed != &node_states[N_MEMORY])
2439		NODEMASK_FREE(nodes_allowed);
2440
2441	return len;
2442out:
2443	NODEMASK_FREE(nodes_allowed);
2444	return err;
2445}
2446
2447static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
2448					 struct kobject *kobj, const char *buf,
2449					 size_t len)
2450{
2451	struct hstate *h;
2452	unsigned long count;
2453	int nid;
2454	int err;
2455
2456	err = kstrtoul(buf, 10, &count);
2457	if (err)
2458		return err;
2459
2460	h = kobj_to_hstate(kobj, &nid);
2461	return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
2462}
2463
2464static ssize_t nr_hugepages_show(struct kobject *kobj,
2465				       struct kobj_attribute *attr, char *buf)
2466{
2467	return nr_hugepages_show_common(kobj, attr, buf);
2468}
2469
2470static ssize_t nr_hugepages_store(struct kobject *kobj,
2471	       struct kobj_attribute *attr, const char *buf, size_t len)
2472{
2473	return nr_hugepages_store_common(false, kobj, buf, len);
2474}
2475HSTATE_ATTR(nr_hugepages);
2476
2477#ifdef CONFIG_NUMA
2478
2479/*
2480 * hstate attribute for optionally mempolicy-based constraint on persistent
2481 * huge page alloc/free.
2482 */
2483static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
2484				       struct kobj_attribute *attr, char *buf)
 
2485{
2486	return nr_hugepages_show_common(kobj, attr, buf);
2487}
2488
2489static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
2490	       struct kobj_attribute *attr, const char *buf, size_t len)
2491{
2492	return nr_hugepages_store_common(true, kobj, buf, len);
2493}
2494HSTATE_ATTR(nr_hugepages_mempolicy);
2495#endif
2496
2497
2498static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
2499					struct kobj_attribute *attr, char *buf)
2500{
2501	struct hstate *h = kobj_to_hstate(kobj, NULL);
2502	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
2503}
2504
2505static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
2506		struct kobj_attribute *attr, const char *buf, size_t count)
2507{
2508	int err;
2509	unsigned long input;
2510	struct hstate *h = kobj_to_hstate(kobj, NULL);
2511
2512	if (hstate_is_gigantic(h))
2513		return -EINVAL;
2514
2515	err = kstrtoul(buf, 10, &input);
2516	if (err)
2517		return err;
2518
2519	spin_lock(&hugetlb_lock);
2520	h->nr_overcommit_huge_pages = input;
2521	spin_unlock(&hugetlb_lock);
2522
2523	return count;
2524}
2525HSTATE_ATTR(nr_overcommit_hugepages);
2526
2527static ssize_t free_hugepages_show(struct kobject *kobj,
2528					struct kobj_attribute *attr, char *buf)
2529{
2530	struct hstate *h;
2531	unsigned long free_huge_pages;
2532	int nid;
2533
2534	h = kobj_to_hstate(kobj, &nid);
2535	if (nid == NUMA_NO_NODE)
2536		free_huge_pages = h->free_huge_pages;
2537	else
2538		free_huge_pages = h->free_huge_pages_node[nid];
2539
2540	return sprintf(buf, "%lu\n", free_huge_pages);
2541}
2542HSTATE_ATTR_RO(free_hugepages);
2543
2544static ssize_t resv_hugepages_show(struct kobject *kobj,
2545					struct kobj_attribute *attr, char *buf)
2546{
2547	struct hstate *h = kobj_to_hstate(kobj, NULL);
2548	return sprintf(buf, "%lu\n", h->resv_huge_pages);
2549}
2550HSTATE_ATTR_RO(resv_hugepages);
2551
2552static ssize_t surplus_hugepages_show(struct kobject *kobj,
2553					struct kobj_attribute *attr, char *buf)
2554{
2555	struct hstate *h;
2556	unsigned long surplus_huge_pages;
2557	int nid;
2558
2559	h = kobj_to_hstate(kobj, &nid);
2560	if (nid == NUMA_NO_NODE)
2561		surplus_huge_pages = h->surplus_huge_pages;
2562	else
2563		surplus_huge_pages = h->surplus_huge_pages_node[nid];
2564
2565	return sprintf(buf, "%lu\n", surplus_huge_pages);
2566}
2567HSTATE_ATTR_RO(surplus_hugepages);
2568
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2569static struct attribute *hstate_attrs[] = {
2570	&nr_hugepages_attr.attr,
2571	&nr_overcommit_hugepages_attr.attr,
2572	&free_hugepages_attr.attr,
2573	&resv_hugepages_attr.attr,
2574	&surplus_hugepages_attr.attr,
2575#ifdef CONFIG_NUMA
2576	&nr_hugepages_mempolicy_attr.attr,
2577#endif
2578	NULL,
2579};
2580
2581static const struct attribute_group hstate_attr_group = {
2582	.attrs = hstate_attrs,
2583};
2584
 
 
 
 
 
 
 
 
 
 
2585static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
2586				    struct kobject **hstate_kobjs,
2587				    const struct attribute_group *hstate_attr_group)
2588{
2589	int retval;
2590	int hi = hstate_index(h);
2591
2592	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
2593	if (!hstate_kobjs[hi])
2594		return -ENOMEM;
2595
2596	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
2597	if (retval)
2598		kobject_put(hstate_kobjs[hi]);
 
 
 
2599
2600	return retval;
2601}
2602
2603static void __init hugetlb_sysfs_init(void)
2604{
2605	struct hstate *h;
2606	int err;
2607
2608	hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
2609	if (!hugepages_kobj)
2610		return;
2611
2612	for_each_hstate(h) {
2613		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
2614					 hstate_kobjs, &hstate_attr_group);
2615		if (err)
2616			pr_err("Hugetlb: Unable to add hstate %s", h->name);
2617	}
 
 
2618}
2619
2620#ifdef CONFIG_NUMA
 
2621
2622/*
2623 * node_hstate/s - associate per node hstate attributes, via their kobjects,
2624 * with node devices in node_devices[] using a parallel array.  The array
2625 * index of a node device or _hstate == node id.
2626 * This is here to avoid any static dependency of the node device driver, in
2627 * the base kernel, on the hugetlb module.
2628 */
2629struct node_hstate {
2630	struct kobject		*hugepages_kobj;
2631	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
2632};
2633static struct node_hstate node_hstates[MAX_NUMNODES];
2634
2635/*
2636 * A subset of global hstate attributes for node devices
2637 */
2638static struct attribute *per_node_hstate_attrs[] = {
2639	&nr_hugepages_attr.attr,
2640	&free_hugepages_attr.attr,
2641	&surplus_hugepages_attr.attr,
2642	NULL,
2643};
2644
2645static const struct attribute_group per_node_hstate_attr_group = {
2646	.attrs = per_node_hstate_attrs,
2647};
2648
2649/*
2650 * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
2651 * Returns node id via non-NULL nidp.
2652 */
2653static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2654{
2655	int nid;
2656
2657	for (nid = 0; nid < nr_node_ids; nid++) {
2658		struct node_hstate *nhs = &node_hstates[nid];
2659		int i;
2660		for (i = 0; i < HUGE_MAX_HSTATE; i++)
2661			if (nhs->hstate_kobjs[i] == kobj) {
2662				if (nidp)
2663					*nidp = nid;
2664				return &hstates[i];
2665			}
2666	}
2667
2668	BUG();
2669	return NULL;
2670}
2671
2672/*
2673 * Unregister hstate attributes from a single node device.
2674 * No-op if no hstate attributes attached.
2675 */
2676static void hugetlb_unregister_node(struct node *node)
2677{
2678	struct hstate *h;
2679	struct node_hstate *nhs = &node_hstates[node->dev.id];
2680
2681	if (!nhs->hugepages_kobj)
2682		return;		/* no hstate attributes */
2683
2684	for_each_hstate(h) {
2685		int idx = hstate_index(h);
2686		if (nhs->hstate_kobjs[idx]) {
2687			kobject_put(nhs->hstate_kobjs[idx]);
2688			nhs->hstate_kobjs[idx] = NULL;
2689		}
 
 
 
 
 
2690	}
2691
2692	kobject_put(nhs->hugepages_kobj);
2693	nhs->hugepages_kobj = NULL;
2694}
2695
2696
2697/*
2698 * Register hstate attributes for a single node device.
2699 * No-op if attributes already registered.
2700 */
2701static void hugetlb_register_node(struct node *node)
2702{
2703	struct hstate *h;
2704	struct node_hstate *nhs = &node_hstates[node->dev.id];
2705	int err;
2706
 
 
 
2707	if (nhs->hugepages_kobj)
2708		return;		/* already allocated */
2709
2710	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
2711							&node->dev.kobj);
2712	if (!nhs->hugepages_kobj)
2713		return;
2714
2715	for_each_hstate(h) {
2716		err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
2717						nhs->hstate_kobjs,
2718						&per_node_hstate_attr_group);
2719		if (err) {
2720			pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
2721				h->name, node->dev.id);
2722			hugetlb_unregister_node(node);
2723			break;
2724		}
2725	}
2726}
2727
2728/*
2729 * hugetlb init time:  register hstate attributes for all registered node
2730 * devices of nodes that have memory.  All on-line nodes should have
2731 * registered their associated device by this time.
2732 */
2733static void __init hugetlb_register_all_nodes(void)
2734{
2735	int nid;
2736
2737	for_each_node_state(nid, N_MEMORY) {
2738		struct node *node = node_devices[nid];
2739		if (node->dev.id == nid)
2740			hugetlb_register_node(node);
2741	}
2742
2743	/*
2744	 * Let the node device driver know we're here so it can
2745	 * [un]register hstate attributes on node hotplug.
2746	 */
2747	register_hugetlbfs_with_node(hugetlb_register_node,
2748				     hugetlb_unregister_node);
2749}
2750#else	/* !CONFIG_NUMA */
2751
2752static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
2753{
2754	BUG();
2755	if (nidp)
2756		*nidp = -1;
2757	return NULL;
2758}
2759
2760static void hugetlb_register_all_nodes(void) { }
2761
2762#endif
2763
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2764static int __init hugetlb_init(void)
2765{
2766	int i;
2767
2768	if (!hugepages_supported())
 
 
 
 
 
2769		return 0;
 
2770
2771	if (!size_to_hstate(default_hstate_size)) {
2772		if (default_hstate_size != 0) {
2773			pr_err("HugeTLB: unsupported default_hugepagesz %lu. Reverting to %lu\n",
2774			       default_hstate_size, HPAGE_SIZE);
2775		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2776
2777		default_hstate_size = HPAGE_SIZE;
2778		if (!size_to_hstate(default_hstate_size))
2779			hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
2780	}
2781	default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
2782	if (default_hstate_max_huge_pages) {
2783		if (!default_hstate.max_huge_pages)
2784			default_hstate.max_huge_pages = default_hstate_max_huge_pages;
2785	}
2786
 
2787	hugetlb_init_hstates();
2788	gather_bootmem_prealloc();
2789	report_hugepages();
2790
2791	hugetlb_sysfs_init();
2792	hugetlb_register_all_nodes();
2793	hugetlb_cgroup_file_init();
2794
2795#ifdef CONFIG_SMP
2796	num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus());
2797#else
2798	num_fault_mutexes = 1;
2799#endif
2800	hugetlb_fault_mutex_table =
2801		kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL);
 
2802	BUG_ON(!hugetlb_fault_mutex_table);
2803
2804	for (i = 0; i < num_fault_mutexes; i++)
2805		mutex_init(&hugetlb_fault_mutex_table[i]);
2806	return 0;
2807}
2808subsys_initcall(hugetlb_init);
2809
2810/* Should be called on processing a hugepagesz=... option */
2811void __init hugetlb_bad_size(void)
2812{
2813	parsed_valid_hugepagesz = false;
2814}
2815
2816void __init hugetlb_add_hstate(unsigned int order)
2817{
2818	struct hstate *h;
2819	unsigned long i;
2820
2821	if (size_to_hstate(PAGE_SIZE << order)) {
2822		pr_warn("hugepagesz= specified twice, ignoring\n");
2823		return;
2824	}
2825	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
2826	BUG_ON(order == 0);
2827	h = &hstates[hugetlb_max_hstate++];
 
2828	h->order = order;
2829	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
2830	h->nr_huge_pages = 0;
2831	h->free_huge_pages = 0;
2832	for (i = 0; i < MAX_NUMNODES; ++i)
2833		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
2834	INIT_LIST_HEAD(&h->hugepage_activelist);
2835	h->next_nid_to_alloc = first_memory_node;
2836	h->next_nid_to_free = first_memory_node;
2837	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
2838					huge_page_size(h)/1024);
2839
2840	parsed_hstate = h;
2841}
2842
2843static int __init hugetlb_nrpages_setup(char *s)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2844{
2845	unsigned long *mhp;
2846	static unsigned long *last_mhp;
 
 
 
 
2847
2848	if (!parsed_valid_hugepagesz) {
2849		pr_warn("hugepages = %s preceded by "
2850			"an unsupported hugepagesz, ignoring\n", s);
2851		parsed_valid_hugepagesz = true;
2852		return 1;
2853	}
 
2854	/*
2855	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
2856	 * so this hugepages= parameter goes to the "default hstate".
 
 
2857	 */
2858	else if (!hugetlb_max_hstate)
2859		mhp = &default_hstate_max_huge_pages;
2860	else
2861		mhp = &parsed_hstate->max_huge_pages;
2862
2863	if (mhp == last_mhp) {
2864		pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
2865		return 1;
2866	}
2867
2868	if (sscanf(s, "%lu", mhp) <= 0)
2869		*mhp = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2870
2871	/*
2872	 * Global state is always initialized later in hugetlb_init.
2873	 * But we need to allocate >= MAX_ORDER hstates here early to still
2874	 * use the bootmem allocator.
2875	 */
2876	if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
2877		hugetlb_hstate_alloc_pages(parsed_hstate);
2878
2879	last_mhp = mhp;
2880
2881	return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2882}
2883__setup("hugepages=", hugetlb_nrpages_setup);
2884
2885static int __init hugetlb_default_setup(char *s)
 
 
 
 
2886{
2887	default_hstate_size = memparse(s, &s);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2888	return 1;
2889}
2890__setup("default_hugepagesz=", hugetlb_default_setup);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2891
2892static unsigned int cpuset_mems_nr(unsigned int *array)
2893{
2894	int node;
2895	unsigned int nr = 0;
 
 
 
2896
2897	for_each_node_mask(node, cpuset_current_mems_allowed)
2898		nr += array[node];
 
 
 
2899
2900	return nr;
2901}
2902
2903#ifdef CONFIG_SYSCTL
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2904static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
2905			 struct ctl_table *table, int write,
2906			 void __user *buffer, size_t *length, loff_t *ppos)
2907{
2908	struct hstate *h = &default_hstate;
2909	unsigned long tmp = h->max_huge_pages;
2910	int ret;
2911
2912	if (!hugepages_supported())
2913		return -EOPNOTSUPP;
2914
2915	table->data = &tmp;
2916	table->maxlen = sizeof(unsigned long);
2917	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2918	if (ret)
2919		goto out;
2920
2921	if (write)
2922		ret = __nr_hugepages_store_common(obey_mempolicy, h,
2923						  NUMA_NO_NODE, tmp, *length);
2924out:
2925	return ret;
2926}
2927
2928int hugetlb_sysctl_handler(struct ctl_table *table, int write,
2929			  void __user *buffer, size_t *length, loff_t *ppos)
2930{
2931
2932	return hugetlb_sysctl_handler_common(false, table, write,
2933							buffer, length, ppos);
2934}
2935
2936#ifdef CONFIG_NUMA
2937int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
2938			  void __user *buffer, size_t *length, loff_t *ppos)
2939{
2940	return hugetlb_sysctl_handler_common(true, table, write,
2941							buffer, length, ppos);
2942}
2943#endif /* CONFIG_NUMA */
2944
2945int hugetlb_overcommit_handler(struct ctl_table *table, int write,
2946			void __user *buffer,
2947			size_t *length, loff_t *ppos)
2948{
2949	struct hstate *h = &default_hstate;
2950	unsigned long tmp;
2951	int ret;
2952
2953	if (!hugepages_supported())
2954		return -EOPNOTSUPP;
2955
2956	tmp = h->nr_overcommit_huge_pages;
2957
2958	if (write && hstate_is_gigantic(h))
2959		return -EINVAL;
2960
2961	table->data = &tmp;
2962	table->maxlen = sizeof(unsigned long);
2963	ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
2964	if (ret)
2965		goto out;
2966
2967	if (write) {
2968		spin_lock(&hugetlb_lock);
2969		h->nr_overcommit_huge_pages = tmp;
2970		spin_unlock(&hugetlb_lock);
2971	}
2972out:
2973	return ret;
2974}
2975
2976#endif /* CONFIG_SYSCTL */
2977
2978void hugetlb_report_meminfo(struct seq_file *m)
2979{
2980	struct hstate *h;
2981	unsigned long total = 0;
2982
2983	if (!hugepages_supported())
2984		return;
2985
2986	for_each_hstate(h) {
2987		unsigned long count = h->nr_huge_pages;
2988
2989		total += (PAGE_SIZE << huge_page_order(h)) * count;
2990
2991		if (h == &default_hstate)
2992			seq_printf(m,
2993				   "HugePages_Total:   %5lu\n"
2994				   "HugePages_Free:    %5lu\n"
2995				   "HugePages_Rsvd:    %5lu\n"
2996				   "HugePages_Surp:    %5lu\n"
2997				   "Hugepagesize:   %8lu kB\n",
2998				   count,
2999				   h->free_huge_pages,
3000				   h->resv_huge_pages,
3001				   h->surplus_huge_pages,
3002				   (PAGE_SIZE << huge_page_order(h)) / 1024);
3003	}
3004
3005	seq_printf(m, "Hugetlb:        %8lu kB\n", total / 1024);
3006}
3007
3008int hugetlb_report_node_meminfo(int nid, char *buf)
3009{
3010	struct hstate *h = &default_hstate;
 
3011	if (!hugepages_supported())
3012		return 0;
3013	return sprintf(buf,
3014		"Node %d HugePages_Total: %5u\n"
3015		"Node %d HugePages_Free:  %5u\n"
3016		"Node %d HugePages_Surp:  %5u\n",
3017		nid, h->nr_huge_pages_node[nid],
3018		nid, h->free_huge_pages_node[nid],
3019		nid, h->surplus_huge_pages_node[nid]);
 
3020}
3021
3022void hugetlb_show_meminfo(void)
3023{
3024	struct hstate *h;
3025	int nid;
3026
3027	if (!hugepages_supported())
3028		return;
3029
3030	for_each_node_state(nid, N_MEMORY)
3031		for_each_hstate(h)
3032			pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
3033				nid,
3034				h->nr_huge_pages_node[nid],
3035				h->free_huge_pages_node[nid],
3036				h->surplus_huge_pages_node[nid],
3037				1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
3038}
3039
3040void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
3041{
3042	seq_printf(m, "HugetlbPages:\t%8lu kB\n",
3043		   atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
3044}
3045
3046/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
3047unsigned long hugetlb_total_pages(void)
3048{
3049	struct hstate *h;
3050	unsigned long nr_total_pages = 0;
3051
3052	for_each_hstate(h)
3053		nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h);
3054	return nr_total_pages;
3055}
3056
3057static int hugetlb_acct_memory(struct hstate *h, long delta)
3058{
3059	int ret = -ENOMEM;
3060
3061	spin_lock(&hugetlb_lock);
 
 
 
3062	/*
3063	 * When cpuset is configured, it breaks the strict hugetlb page
3064	 * reservation as the accounting is done on a global variable. Such
3065	 * reservation is completely rubbish in the presence of cpuset because
3066	 * the reservation is not checked against page availability for the
3067	 * current cpuset. Application can still potentially OOM'ed by kernel
3068	 * with lack of free htlb page in cpuset that the task is in.
3069	 * Attempt to enforce strict accounting with cpuset is almost
3070	 * impossible (or too ugly) because cpuset is too fluid that
3071	 * task or memory node can be dynamically moved between cpusets.
3072	 *
3073	 * The change of semantics for shared hugetlb mapping with cpuset is
3074	 * undesirable. However, in order to preserve some of the semantics,
3075	 * we fall back to check against current free page availability as
3076	 * a best attempt and hopefully to minimize the impact of changing
3077	 * semantics that cpuset has.
 
 
 
 
 
 
3078	 */
3079	if (delta > 0) {
3080		if (gather_surplus_pages(h, delta) < 0)
3081			goto out;
3082
3083		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
3084			return_unused_surplus_pages(h, delta);
3085			goto out;
3086		}
3087	}
3088
3089	ret = 0;
3090	if (delta < 0)
3091		return_unused_surplus_pages(h, (unsigned long) -delta);
3092
3093out:
3094	spin_unlock(&hugetlb_lock);
3095	return ret;
3096}
3097
3098static void hugetlb_vm_op_open(struct vm_area_struct *vma)
3099{
3100	struct resv_map *resv = vma_resv_map(vma);
3101
3102	/*
 
3103	 * This new VMA should share its siblings reservation map if present.
3104	 * The VMA will only ever have a valid reservation map pointer where
3105	 * it is being copied for another still existing VMA.  As that VMA
3106	 * has a reference to the reservation map it cannot disappear until
3107	 * after this open call completes.  It is therefore safe to take a
3108	 * new reference here without additional locking.
3109	 */
3110	if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
 
3111		kref_get(&resv->refs);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3112}
3113
3114static void hugetlb_vm_op_close(struct vm_area_struct *vma)
3115{
3116	struct hstate *h = hstate_vma(vma);
3117	struct resv_map *resv = vma_resv_map(vma);
3118	struct hugepage_subpool *spool = subpool_vma(vma);
3119	unsigned long reserve, start, end;
3120	long gbl_reserve;
3121
 
 
 
3122	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
3123		return;
3124
3125	start = vma_hugecache_offset(h, vma, vma->vm_start);
3126	end = vma_hugecache_offset(h, vma, vma->vm_end);
3127
3128	reserve = (end - start) - region_count(resv, start, end);
3129
3130	kref_put(&resv->refs, resv_map_release);
3131
3132	if (reserve) {
3133		/*
3134		 * Decrement reserve counts.  The global reserve count may be
3135		 * adjusted if the subpool has a minimum size.
3136		 */
3137		gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
3138		hugetlb_acct_memory(h, -gbl_reserve);
3139	}
 
 
3140}
3141
3142static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
3143{
3144	if (addr & ~(huge_page_mask(hstate_vma(vma))))
3145		return -EINVAL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3146	return 0;
3147}
3148
3149static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma)
3150{
3151	struct hstate *hstate = hstate_vma(vma);
3152
3153	return 1UL << huge_page_shift(hstate);
3154}
3155
3156/*
3157 * We cannot handle pagefaults against hugetlb pages at all.  They cause
3158 * handle_mm_fault() to try to instantiate regular-sized pages in the
3159 * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
3160 * this far.
3161 */
3162static int hugetlb_vm_op_fault(struct vm_fault *vmf)
3163{
3164	BUG();
3165	return 0;
3166}
3167
 
 
 
 
 
 
 
3168const struct vm_operations_struct hugetlb_vm_ops = {
3169	.fault = hugetlb_vm_op_fault,
3170	.open = hugetlb_vm_op_open,
3171	.close = hugetlb_vm_op_close,
3172	.split = hugetlb_vm_op_split,
3173	.pagesize = hugetlb_vm_op_pagesize,
3174};
3175
3176static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
3177				int writable)
3178{
3179	pte_t entry;
 
3180
3181	if (writable) {
3182		entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page,
3183					 vma->vm_page_prot)));
3184	} else {
3185		entry = huge_pte_wrprotect(mk_huge_pte(page,
3186					   vma->vm_page_prot));
3187	}
3188	entry = pte_mkyoung(entry);
3189	entry = pte_mkhuge(entry);
3190	entry = arch_make_huge_pte(entry, vma, page, writable);
3191
3192	return entry;
3193}
3194
3195static void set_huge_ptep_writable(struct vm_area_struct *vma,
3196				   unsigned long address, pte_t *ptep)
3197{
3198	pte_t entry;
3199
3200	entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep)));
3201	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
3202		update_mmu_cache(vma, address, ptep);
3203}
3204
3205bool is_hugetlb_entry_migration(pte_t pte)
3206{
3207	swp_entry_t swp;
3208
3209	if (huge_pte_none(pte) || pte_present(pte))
3210		return false;
3211	swp = pte_to_swp_entry(pte);
3212	if (non_swap_entry(swp) && is_migration_entry(swp))
3213		return true;
3214	else
3215		return false;
3216}
3217
3218static int is_hugetlb_entry_hwpoisoned(pte_t pte)
3219{
3220	swp_entry_t swp;
3221
3222	if (huge_pte_none(pte) || pte_present(pte))
3223		return 0;
3224	swp = pte_to_swp_entry(pte);
3225	if (non_swap_entry(swp) && is_hwpoison_entry(swp))
3226		return 1;
3227	else
3228		return 0;
 
 
 
 
 
 
 
 
 
 
 
3229}
3230
3231int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
3232			    struct vm_area_struct *vma)
 
3233{
3234	pte_t *src_pte, *dst_pte, entry;
3235	struct page *ptepage;
3236	unsigned long addr;
3237	int cow;
3238	struct hstate *h = hstate_vma(vma);
3239	unsigned long sz = huge_page_size(h);
3240	unsigned long mmun_start;	/* For mmu_notifiers */
3241	unsigned long mmun_end;		/* For mmu_notifiers */
 
3242	int ret = 0;
3243
3244	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
3245
3246	mmun_start = vma->vm_start;
3247	mmun_end = vma->vm_end;
3248	if (cow)
3249		mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
 
 
 
 
 
 
 
 
 
 
3250
3251	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
 
3252		spinlock_t *src_ptl, *dst_ptl;
3253		src_pte = huge_pte_offset(src, addr, sz);
3254		if (!src_pte)
 
3255			continue;
3256		dst_pte = huge_pte_alloc(dst, addr, sz);
 
3257		if (!dst_pte) {
3258			ret = -ENOMEM;
3259			break;
3260		}
3261
3262		/* If the pagetables are shared don't copy or take references */
3263		if (dst_pte == src_pte)
 
 
 
 
 
 
 
 
3264			continue;
 
3265
3266		dst_ptl = huge_pte_lock(h, dst, dst_pte);
3267		src_ptl = huge_pte_lockptr(h, src, src_pte);
3268		spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
3269		entry = huge_ptep_get(src_pte);
3270		if (huge_pte_none(entry)) { /* skip none entry */
 
 
 
 
3271			;
3272		} else if (unlikely(is_hugetlb_entry_migration(entry) ||
3273				    is_hugetlb_entry_hwpoisoned(entry))) {
 
 
 
 
 
3274			swp_entry_t swp_entry = pte_to_swp_entry(entry);
 
3275
3276			if (is_write_migration_entry(swp_entry) && cow) {
3277				/*
3278				 * COW mappings require pages in both
3279				 * parent and child to be set to read.
3280				 */
3281				make_migration_entry_read(&swp_entry);
 
3282				entry = swp_entry_to_pte(swp_entry);
3283				set_huge_swap_pte_at(src, addr, src_pte,
3284						     entry, sz);
 
3285			}
3286			set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
 
 
 
 
 
 
 
 
 
 
 
 
3287		} else {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3288			if (cow) {
3289				/*
3290				 * No need to notify as we are downgrading page
3291				 * table protection not changing it to point
3292				 * to a new page.
3293				 *
3294				 * See Documentation/vm/mmu_notifier.txt
3295				 */
3296				huge_ptep_set_wrprotect(src, addr, src_pte);
 
3297			}
3298			entry = huge_ptep_get(src_pte);
3299			ptepage = pte_page(entry);
3300			get_page(ptepage);
3301			page_dup_rmap(ptepage, true);
3302			set_huge_pte_at(dst, addr, dst_pte, entry);
3303			hugetlb_count_add(pages_per_huge_page(h), dst);
3304		}
3305		spin_unlock(src_ptl);
3306		spin_unlock(dst_ptl);
3307	}
3308
3309	if (cow)
3310		mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
 
 
 
 
3311
3312	return ret;
3313}
3314
3315void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
3316			    unsigned long start, unsigned long end,
3317			    struct page *ref_page)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3318{
3319	struct mm_struct *mm = vma->vm_mm;
3320	unsigned long address;
3321	pte_t *ptep;
3322	pte_t pte;
3323	spinlock_t *ptl;
3324	struct page *page;
3325	struct hstate *h = hstate_vma(vma);
3326	unsigned long sz = huge_page_size(h);
3327	const unsigned long mmun_start = start;	/* For mmu_notifiers */
3328	const unsigned long mmun_end   = end;	/* For mmu_notifiers */
3329
3330	WARN_ON(!is_vm_hugetlb_page(vma));
3331	BUG_ON(start & ~huge_page_mask(h));
3332	BUG_ON(end & ~huge_page_mask(h));
3333
3334	/*
3335	 * This is a hugetlb vma, all the pte entries should point
3336	 * to huge page.
3337	 */
3338	tlb_remove_check_page_size_change(tlb, sz);
3339	tlb_start_vma(tlb, vma);
3340	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 
3341	address = start;
3342	for (; address < end; address += sz) {
3343		ptep = huge_pte_offset(mm, address, sz);
3344		if (!ptep)
 
3345			continue;
 
3346
3347		ptl = huge_pte_lock(h, mm, ptep);
3348		if (huge_pmd_unshare(mm, &address, ptep)) {
3349			spin_unlock(ptl);
 
 
 
3350			continue;
3351		}
3352
3353		pte = huge_ptep_get(ptep);
3354		if (huge_pte_none(pte)) {
3355			spin_unlock(ptl);
3356			continue;
3357		}
3358
3359		/*
3360		 * Migrating hugepage or HWPoisoned hugepage is already
3361		 * unmapped and its refcount is dropped, so just clear pte here.
3362		 */
3363		if (unlikely(!pte_present(pte))) {
3364			huge_pte_clear(mm, address, ptep, sz);
 
 
 
 
 
 
 
 
 
 
 
3365			spin_unlock(ptl);
3366			continue;
3367		}
3368
3369		page = pte_page(pte);
3370		/*
3371		 * If a reference page is supplied, it is because a specific
3372		 * page is being unmapped, not a range. Ensure the page we
3373		 * are about to unmap is the actual page of interest.
3374		 */
3375		if (ref_page) {
3376			if (page != ref_page) {
3377				spin_unlock(ptl);
3378				continue;
3379			}
3380			/*
3381			 * Mark the VMA as having unmapped its page so that
3382			 * future faults in this VMA will fail rather than
3383			 * looking like data was lost
3384			 */
3385			set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
3386		}
3387
3388		pte = huge_ptep_get_and_clear(mm, address, ptep);
3389		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
3390		if (huge_pte_dirty(pte))
3391			set_page_dirty(page);
3392
 
 
 
 
3393		hugetlb_count_sub(pages_per_huge_page(h), mm);
3394		page_remove_rmap(page, true);
3395
3396		spin_unlock(ptl);
3397		tlb_remove_page_size(tlb, page, huge_page_size(h));
3398		/*
3399		 * Bail out after unmapping reference page if supplied
3400		 */
3401		if (ref_page)
3402			break;
3403	}
3404	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3405	tlb_end_vma(tlb, vma);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3406}
3407
3408void __unmap_hugepage_range_final(struct mmu_gather *tlb,
3409			  struct vm_area_struct *vma, unsigned long start,
3410			  unsigned long end, struct page *ref_page)
 
3411{
3412	__unmap_hugepage_range(tlb, vma, start, end, ref_page);
 
3413
3414	/*
3415	 * Clear this flag so that x86's huge_pmd_share page_table_shareable
3416	 * test will fail on a vma being torn down, and not grab a page table
3417	 * on its way out.  We're lucky that the flag has such an appropriate
3418	 * name, and can in fact be safely cleared here. We could clear it
3419	 * before the __unmap_hugepage_range above, but all that's necessary
3420	 * is to clear it before releasing the i_mmap_rwsem. This works
3421	 * because in the context this is called, the VMA is about to be
3422	 * destroyed and the i_mmap_rwsem is held.
3423	 */
3424	vma->vm_flags &= ~VM_MAYSHARE;
 
 
 
 
 
 
 
 
3425}
3426
3427void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
3428			  unsigned long end, struct page *ref_page)
 
3429{
3430	struct mm_struct *mm;
3431	struct mmu_gather tlb;
3432
3433	mm = vma->vm_mm;
 
 
 
 
3434
3435	tlb_gather_mmu(&tlb, mm, start, end);
3436	__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
3437	tlb_finish_mmu(&tlb, start, end);
 
3438}
3439
3440/*
3441 * This is called when the original mapper is failing to COW a MAP_PRIVATE
3442 * mappping it owns the reserve page for. The intention is to unmap the page
3443 * from other VMAs and let the children be SIGKILLed if they are faulting the
3444 * same region.
3445 */
3446static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
3447			      struct page *page, unsigned long address)
3448{
3449	struct hstate *h = hstate_vma(vma);
3450	struct vm_area_struct *iter_vma;
3451	struct address_space *mapping;
3452	pgoff_t pgoff;
3453
3454	/*
3455	 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
3456	 * from page cache lookup which is in HPAGE_SIZE units.
3457	 */
3458	address = address & huge_page_mask(h);
3459	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) +
3460			vma->vm_pgoff;
3461	mapping = vma->vm_file->f_mapping;
3462
3463	/*
3464	 * Take the mapping lock for the duration of the table walk. As
3465	 * this mapping should be shared between all the VMAs,
3466	 * __unmap_hugepage_range() is called as the lock is already held
3467	 */
3468	i_mmap_lock_write(mapping);
3469	vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) {
3470		/* Do not unmap the current VMA */
3471		if (iter_vma == vma)
3472			continue;
3473
3474		/*
3475		 * Shared VMAs have their own reserves and do not affect
3476		 * MAP_PRIVATE accounting but it is possible that a shared
3477		 * VMA is using the same page so check and skip such VMAs.
3478		 */
3479		if (iter_vma->vm_flags & VM_MAYSHARE)
3480			continue;
3481
3482		/*
3483		 * Unmap the page from other VMAs without their own reserves.
3484		 * They get marked to be SIGKILLed if they fault in these
3485		 * areas. This is because a future no-page fault on this VMA
3486		 * could insert a zeroed page instead of the data existing
3487		 * from the time of fork. This would look like data corruption
3488		 */
3489		if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
3490			unmap_hugepage_range(iter_vma, address,
3491					     address + huge_page_size(h), page);
3492	}
3493	i_mmap_unlock_write(mapping);
3494}
3495
3496/*
3497 * Hugetlb_cow() should be called with page lock of the original hugepage held.
3498 * Called with hugetlb_instantiation_mutex held and pte_page locked so we
3499 * cannot race with other handlers or page migration.
3500 * Keep the pte_same checks anyway to make transition from the mutex easier.
3501 */
3502static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
3503		       unsigned long address, pte_t *ptep,
3504		       struct page *pagecache_page, spinlock_t *ptl)
3505{
 
3506	pte_t pte;
3507	struct hstate *h = hstate_vma(vma);
3508	struct page *old_page, *new_page;
3509	int ret = 0, outside_reserve = 0;
3510	unsigned long mmun_start;	/* For mmu_notifiers */
3511	unsigned long mmun_end;		/* For mmu_notifiers */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3512
3513	pte = huge_ptep_get(ptep);
3514	old_page = pte_page(pte);
3515
 
 
3516retry_avoidcopy:
3517	/* If no-one else is actually using this page, avoid the copy
3518	 * and just make the page writable */
 
 
3519	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
3520		page_move_anon_rmap(old_page, vma);
3521		set_huge_ptep_writable(vma, address, ptep);
 
 
 
 
3522		return 0;
3523	}
 
 
3524
3525	/*
3526	 * If the process that created a MAP_PRIVATE mapping is about to
3527	 * perform a COW due to a shared page count, attempt to satisfy
3528	 * the allocation without using the existing reserves. The pagecache
3529	 * page is used to determine if the reserve at this address was
3530	 * consumed or not. If reserves were used, a partial faulted mapping
3531	 * at the time of fork() could consume its reserves on COW instead
3532	 * of the full address range.
3533	 */
3534	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
3535			old_page != pagecache_page)
3536		outside_reserve = 1;
3537
3538	get_page(old_page);
3539
3540	/*
3541	 * Drop page table lock as buddy allocator may be called. It will
3542	 * be acquired again before returning to the caller, as expected.
3543	 */
3544	spin_unlock(ptl);
3545	new_page = alloc_huge_page(vma, address, outside_reserve);
3546
3547	if (IS_ERR(new_page)) {
3548		/*
3549		 * If a process owning a MAP_PRIVATE mapping fails to COW,
3550		 * it is due to references held by a child and an insufficient
3551		 * huge page pool. To guarantee the original mappers
3552		 * reliability, unmap the page from child processes. The child
3553		 * may get SIGKILLed if it later faults.
3554		 */
3555		if (outside_reserve) {
 
 
 
 
3556			put_page(old_page);
3557			BUG_ON(huge_pte_none(pte));
3558			unmap_ref_private(mm, vma, old_page, address);
3559			BUG_ON(huge_pte_none(pte));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3560			spin_lock(ptl);
3561			ptep = huge_pte_offset(mm, address & huge_page_mask(h),
3562					       huge_page_size(h));
3563			if (likely(ptep &&
3564				   pte_same(huge_ptep_get(ptep), pte)))
3565				goto retry_avoidcopy;
3566			/*
3567			 * race occurs while re-acquiring page table
3568			 * lock, and our job is done.
3569			 */
 
3570			return 0;
3571		}
3572
3573		ret = (PTR_ERR(new_page) == -ENOMEM) ?
3574			VM_FAULT_OOM : VM_FAULT_SIGBUS;
3575		goto out_release_old;
3576	}
3577
3578	/*
3579	 * When the original hugepage is shared one, it does not have
3580	 * anon_vma prepared.
3581	 */
3582	if (unlikely(anon_vma_prepare(vma))) {
3583		ret = VM_FAULT_OOM;
3584		goto out_release_all;
3585	}
3586
3587	copy_user_huge_page(new_page, old_page, address, vma,
3588			    pages_per_huge_page(h));
3589	__SetPageUptodate(new_page);
3590	set_page_huge_active(new_page);
3591
3592	mmun_start = address & huge_page_mask(h);
3593	mmun_end = mmun_start + huge_page_size(h);
3594	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3595
3596	/*
3597	 * Retake the page table lock to check for racing updates
3598	 * before the page tables are altered
3599	 */
3600	spin_lock(ptl);
3601	ptep = huge_pte_offset(mm, address & huge_page_mask(h),
3602			       huge_page_size(h));
3603	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
3604		ClearPagePrivate(new_page);
3605
3606		/* Break COW */
3607		huge_ptep_clear_flush(vma, address, ptep);
3608		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
3609		set_huge_pte_at(mm, address, ptep,
3610				make_huge_pte(vma, new_page, 1));
3611		page_remove_rmap(old_page, true);
3612		hugepage_add_new_anon_rmap(new_page, vma, address);
3613		/* Make the old page be freed below */
3614		new_page = old_page;
3615	}
3616	spin_unlock(ptl);
3617	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3618out_release_all:
3619	restore_reserve_on_error(h, vma, address, new_page);
 
 
 
 
 
3620	put_page(new_page);
3621out_release_old:
3622	put_page(old_page);
3623
3624	spin_lock(ptl); /* Caller expects lock to be held */
3625	return ret;
3626}
3627
3628/* Return the pagecache page at a given address within a VMA */
3629static struct page *hugetlbfs_pagecache_page(struct hstate *h,
3630			struct vm_area_struct *vma, unsigned long address)
3631{
3632	struct address_space *mapping;
3633	pgoff_t idx;
3634
3635	mapping = vma->vm_file->f_mapping;
3636	idx = vma_hugecache_offset(h, vma, address);
3637
3638	return find_lock_page(mapping, idx);
 
3639}
3640
3641/*
3642 * Return whether there is a pagecache page to back given address within VMA.
3643 * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
3644 */
3645static bool hugetlbfs_pagecache_present(struct hstate *h,
3646			struct vm_area_struct *vma, unsigned long address)
3647{
3648	struct address_space *mapping;
3649	pgoff_t idx;
3650	struct page *page;
3651
3652	mapping = vma->vm_file->f_mapping;
3653	idx = vma_hugecache_offset(h, vma, address);
3654
3655	page = find_get_page(mapping, idx);
3656	if (page)
3657		put_page(page);
3658	return page != NULL;
3659}
3660
3661int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
3662			   pgoff_t idx)
3663{
 
3664	struct inode *inode = mapping->host;
3665	struct hstate *h = hstate_inode(inode);
3666	int err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
3667
3668	if (err)
 
 
 
 
3669		return err;
3670	ClearPagePrivate(page);
 
 
 
 
 
 
 
3671
3672	spin_lock(&inode->i_lock);
3673	inode->i_blocks += blocks_per_huge_page(h);
3674	spin_unlock(&inode->i_lock);
3675	return 0;
3676}
3677
3678static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
3679			   struct address_space *mapping, pgoff_t idx,
3680			   unsigned long address, pte_t *ptep, unsigned int flags)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3681{
3682	struct hstate *h = hstate_vma(vma);
3683	int ret = VM_FAULT_SIGBUS;
3684	int anon_rmap = 0;
3685	unsigned long size;
3686	struct page *page;
3687	pte_t new_pte;
3688	spinlock_t *ptl;
 
 
 
3689
3690	/*
3691	 * Currently, we are forced to kill the process in the event the
3692	 * original mapper has unmapped pages from the child due to a failed
3693	 * COW. Warn that such a situation has occurred as it may not be obvious
 
3694	 */
3695	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
3696		pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n",
3697			   current->pid);
3698		return ret;
3699	}
3700
3701	/*
3702	 * Use page lock to guard against racing truncation
3703	 * before we get page_table_lock.
3704	 */
3705retry:
3706	page = find_lock_page(mapping, idx);
3707	if (!page) {
3708		size = i_size_read(mapping->host) >> huge_page_shift(h);
3709		if (idx >= size)
3710			goto out;
3711
3712		/*
3713		 * Check for page in userfault range
3714		 */
3715		if (userfaultfd_missing(vma)) {
3716			u32 hash;
3717			struct vm_fault vmf = {
3718				.vma = vma,
3719				.address = address,
3720				.flags = flags,
3721				/*
3722				 * Hard to debug if it ends up being
3723				 * used by a callee that assumes
3724				 * something about the other
3725				 * uninitialized fields... same as in
3726				 * memory.c
3727				 */
3728			};
3729
3730			/*
3731			 * hugetlb_fault_mutex must be dropped before
3732			 * handling userfault.  Reacquire after handling
3733			 * fault to make calling code simpler.
 
 
 
 
 
 
 
 
 
 
 
 
3734			 */
3735			hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping,
3736							idx, address);
3737			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3738			ret = handle_userfault(&vmf, VM_UFFD_MISSING);
3739			mutex_lock(&hugetlb_fault_mutex_table[hash]);
3740			goto out;
 
 
3741		}
3742
3743		page = alloc_huge_page(vma, address, 0);
3744		if (IS_ERR(page)) {
3745			ret = PTR_ERR(page);
3746			if (ret == -ENOMEM)
3747				ret = VM_FAULT_OOM;
 
 
 
 
 
 
 
 
 
 
 
3748			else
3749				ret = VM_FAULT_SIGBUS;
3750			goto out;
3751		}
3752		clear_huge_page(page, address, pages_per_huge_page(h));
3753		__SetPageUptodate(page);
3754		set_page_huge_active(page);
3755
3756		if (vma->vm_flags & VM_MAYSHARE) {
3757			int err = huge_add_to_page_cache(page, mapping, idx);
3758			if (err) {
 
 
 
 
 
 
 
 
3759				put_page(page);
3760				if (err == -EEXIST)
3761					goto retry;
3762				goto out;
3763			}
 
3764		} else {
3765			lock_page(page);
3766			if (unlikely(anon_vma_prepare(vma))) {
3767				ret = VM_FAULT_OOM;
3768				goto backout_unlocked;
3769			}
3770			anon_rmap = 1;
3771		}
3772	} else {
3773		/*
3774		 * If memory error occurs between mmap() and fault, some process
3775		 * don't have hwpoisoned swap entry for errored virtual address.
3776		 * So we need to block hugepage fault by PG_hwpoison bit check.
3777		 */
3778		if (unlikely(PageHWPoison(page))) {
3779			ret = VM_FAULT_HWPOISON |
3780				VM_FAULT_SET_HINDEX(hstate_index(h));
3781			goto backout_unlocked;
3782		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3783	}
3784
3785	/*
3786	 * If we are going to COW a private mapping later, we examine the
3787	 * pending reservations for this page now. This will ensure that
3788	 * any allocations necessary to record that reservation occur outside
3789	 * the spinlock.
3790	 */
3791	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3792		if (vma_needs_reservation(h, vma, address) < 0) {
3793			ret = VM_FAULT_OOM;
3794			goto backout_unlocked;
3795		}
3796		/* Just decrements count, does not deallocate */
3797		vma_end_reservation(h, vma, address);
3798	}
3799
3800	ptl = huge_pte_lock(h, mm, ptep);
3801	size = i_size_read(mapping->host) >> huge_page_shift(h);
3802	if (idx >= size)
3803		goto backout;
3804
3805	ret = 0;
3806	if (!huge_pte_none(huge_ptep_get(ptep)))
 
3807		goto backout;
3808
3809	if (anon_rmap) {
3810		ClearPagePrivate(page);
3811		hugepage_add_new_anon_rmap(page, vma, address);
3812	} else
3813		page_dup_rmap(page, true);
3814	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
3815				&& (vma->vm_flags & VM_SHARED)));
3816	set_huge_pte_at(mm, address, ptep, new_pte);
 
 
 
 
 
 
3817
3818	hugetlb_count_add(pages_per_huge_page(h), mm);
3819	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3820		/* Optimization, do the COW without a second fault */
3821		ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
3822	}
3823
3824	spin_unlock(ptl);
 
 
 
 
 
 
 
 
 
3825	unlock_page(page);
3826out:
 
 
3827	return ret;
3828
3829backout:
3830	spin_unlock(ptl);
3831backout_unlocked:
 
 
 
3832	unlock_page(page);
3833	restore_reserve_on_error(h, vma, address, page);
3834	put_page(page);
3835	goto out;
3836}
3837
3838#ifdef CONFIG_SMP
3839u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3840			    struct vm_area_struct *vma,
3841			    struct address_space *mapping,
3842			    pgoff_t idx, unsigned long address)
3843{
3844	unsigned long key[2];
3845	u32 hash;
3846
3847	if (vma->vm_flags & VM_SHARED) {
3848		key[0] = (unsigned long) mapping;
3849		key[1] = idx;
3850	} else {
3851		key[0] = (unsigned long) mm;
3852		key[1] = address >> huge_page_shift(h);
3853	}
3854
3855	hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0);
3856
3857	return hash & (num_fault_mutexes - 1);
3858}
3859#else
3860/*
3861 * For uniprocesor systems we always use a single mutex, so just
3862 * return 0 and avoid the hashing overhead.
3863 */
3864u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,
3865			    struct vm_area_struct *vma,
3866			    struct address_space *mapping,
3867			    pgoff_t idx, unsigned long address)
3868{
3869	return 0;
3870}
3871#endif
3872
3873int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3874			unsigned long address, unsigned int flags)
3875{
3876	pte_t *ptep, entry;
3877	spinlock_t *ptl;
3878	int ret;
3879	u32 hash;
3880	pgoff_t idx;
3881	struct page *page = NULL;
3882	struct page *pagecache_page = NULL;
3883	struct hstate *h = hstate_vma(vma);
3884	struct address_space *mapping;
3885	int need_wait_lock = 0;
 
3886
3887	address &= huge_page_mask(h);
3888
3889	ptep = huge_pte_offset(mm, address, huge_page_size(h));
3890	if (ptep) {
 
 
 
 
 
3891		entry = huge_ptep_get(ptep);
3892		if (unlikely(is_hugetlb_entry_migration(entry))) {
3893			migration_entry_wait_huge(vma, mm, ptep);
3894			return 0;
3895		} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
3896			return VM_FAULT_HWPOISON_LARGE |
3897				VM_FAULT_SET_HINDEX(hstate_index(h));
3898	} else {
3899		ptep = huge_pte_alloc(mm, address, huge_page_size(h));
3900		if (!ptep)
3901			return VM_FAULT_OOM;
3902	}
3903
3904	mapping = vma->vm_file->f_mapping;
3905	idx = vma_hugecache_offset(h, vma, address);
3906
3907	/*
3908	 * Serialize hugepage allocation and instantiation, so that we don't
3909	 * get spurious allocation failures if two CPUs race to instantiate
3910	 * the same page in the page cache.
3911	 */
3912	hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping, idx, address);
 
 
3913	mutex_lock(&hugetlb_fault_mutex_table[hash]);
3914
3915	entry = huge_ptep_get(ptep);
3916	if (huge_pte_none(entry)) {
3917		ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
3918		goto out_mutex;
 
 
 
 
 
 
 
 
 
 
 
3919	}
3920
 
 
 
 
 
 
 
 
 
 
3921	ret = 0;
3922
3923	/*
3924	 * entry could be a migration/hwpoison entry at this point, so this
3925	 * check prevents the kernel from going below assuming that we have
3926	 * a active hugepage in pagecache. This goto expects the 2nd page fault,
3927	 * and is_hugetlb_entry_(migration|hwpoisoned) check will properly
3928	 * handle it.
3929	 */
3930	if (!pte_present(entry))
3931		goto out_mutex;
3932
3933	/*
3934	 * If we are going to COW the mapping later, we examine the pending
3935	 * reservations for this page now. This will ensure that any
3936	 * allocations necessary to record that reservation occur outside the
3937	 * spinlock. For private mappings, we also lookup the pagecache
3938	 * page now as it is used to determine if a reservation has been
3939	 * consumed.
3940	 */
3941	if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
3942		if (vma_needs_reservation(h, vma, address) < 0) {
 
3943			ret = VM_FAULT_OOM;
3944			goto out_mutex;
3945		}
3946		/* Just decrements count, does not deallocate */
3947		vma_end_reservation(h, vma, address);
3948
3949		if (!(vma->vm_flags & VM_MAYSHARE))
3950			pagecache_page = hugetlbfs_pagecache_page(h,
3951								vma, address);
3952	}
3953
3954	ptl = huge_pte_lock(h, mm, ptep);
3955
3956	/* Check for a racing update before calling hugetlb_cow */
3957	if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
3958		goto out_ptl;
3959
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3960	/*
3961	 * hugetlb_cow() requires page locks of pte_page(entry) and
3962	 * pagecache_page, so here we need take the former one
3963	 * when page != pagecache_page or !pagecache_page.
3964	 */
3965	page = pte_page(entry);
3966	if (page != pagecache_page)
3967		if (!trylock_page(page)) {
3968			need_wait_lock = 1;
3969			goto out_ptl;
3970		}
3971
3972	get_page(page);
3973
3974	if (flags & FAULT_FLAG_WRITE) {
3975		if (!huge_pte_write(entry)) {
3976			ret = hugetlb_cow(mm, vma, address, ptep,
3977					  pagecache_page, ptl);
3978			goto out_put_page;
 
 
3979		}
3980		entry = huge_pte_mkdirty(entry);
3981	}
3982	entry = pte_mkyoung(entry);
3983	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
3984						flags & FAULT_FLAG_WRITE))
3985		update_mmu_cache(vma, address, ptep);
3986out_put_page:
3987	if (page != pagecache_page)
3988		unlock_page(page);
3989	put_page(page);
3990out_ptl:
3991	spin_unlock(ptl);
3992
3993	if (pagecache_page) {
3994		unlock_page(pagecache_page);
3995		put_page(pagecache_page);
3996	}
3997out_mutex:
 
3998	mutex_unlock(&hugetlb_fault_mutex_table[hash]);
3999	/*
4000	 * Generally it's safe to hold refcount during waiting page lock. But
4001	 * here we just wait to defer the next page fault to avoid busy loop and
4002	 * the page is not used after unlocked before returning from the current
4003	 * page fault. So we are safe from accessing freed page, even if we wait
4004	 * here without taking refcount.
4005	 */
4006	if (need_wait_lock)
4007		wait_on_page_locked(page);
4008	return ret;
4009}
4010
 
4011/*
4012 * Used by userfaultfd UFFDIO_COPY.  Based on mcopy_atomic_pte with
4013 * modifications for huge pages.
4014 */
4015int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
4016			    pte_t *dst_pte,
4017			    struct vm_area_struct *dst_vma,
4018			    unsigned long dst_addr,
4019			    unsigned long src_addr,
4020			    struct page **pagep)
 
 
4021{
4022	struct address_space *mapping;
4023	pgoff_t idx;
 
 
4024	unsigned long size;
4025	int vm_shared = dst_vma->vm_flags & VM_SHARED;
4026	struct hstate *h = hstate_vma(dst_vma);
4027	pte_t _dst_pte;
4028	spinlock_t *ptl;
4029	int ret;
4030	struct page *page;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4031
4032	if (!*pagep) {
4033		ret = -ENOMEM;
4034		page = alloc_huge_page(dst_vma, dst_addr, 0);
4035		if (IS_ERR(page))
 
4036			goto out;
 
4037
4038		ret = copy_huge_page_from_user(page,
4039						(const void __user *) src_addr,
4040						pages_per_huge_page(h), false);
4041
4042		/* fallback to copy_from_user outside mmap_sem */
4043		if (unlikely(ret)) {
4044			ret = -EFAULT;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4045			*pagep = page;
4046			/* don't free the page */
 
 
 
4047			goto out;
4048		}
4049	} else {
4050		page = *pagep;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4051		*pagep = NULL;
4052	}
4053
4054	/*
4055	 * The memory barrier inside __SetPageUptodate makes sure that
4056	 * preceding stores to the page contents become visible before
4057	 * the set_pte_at() write.
4058	 */
4059	__SetPageUptodate(page);
4060	set_page_huge_active(page);
4061
4062	mapping = dst_vma->vm_file->f_mapping;
4063	idx = vma_hugecache_offset(h, dst_vma, dst_addr);
4064
4065	/*
4066	 * If shared, add to page cache
4067	 */
4068	if (vm_shared) {
4069		size = i_size_read(mapping->host) >> huge_page_shift(h);
4070		ret = -EFAULT;
4071		if (idx >= size)
4072			goto out_release_nounlock;
4073
4074		/*
4075		 * Serialization between remove_inode_hugepages() and
4076		 * huge_add_to_page_cache() below happens through the
4077		 * hugetlb_fault_mutex_table that here must be hold by
4078		 * the caller.
4079		 */
4080		ret = huge_add_to_page_cache(page, mapping, idx);
4081		if (ret)
4082			goto out_release_nounlock;
 
4083	}
4084
4085	ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
4086	spin_lock(ptl);
4087
4088	/*
4089	 * Recheck the i_size after holding PT lock to make sure not
4090	 * to leave any page mapped (as page_mapped()) beyond the end
4091	 * of the i_size (remove_inode_hugepages() is strict about
4092	 * enforcing that). If we bail out here, we'll also leave a
4093	 * page in the radix tree in the vm_shared case beyond the end
4094	 * of the i_size, but remove_inode_hugepages() will take care
4095	 * of it as soon as we drop the hugetlb_fault_mutex_table.
4096	 */
4097	size = i_size_read(mapping->host) >> huge_page_shift(h);
4098	ret = -EFAULT;
4099	if (idx >= size)
4100		goto out_release_unlock;
4101
 
 
 
 
 
4102	ret = -EEXIST;
4103	if (!huge_pte_none(huge_ptep_get(dst_pte)))
4104		goto out_release_unlock;
4105
4106	if (vm_shared) {
4107		page_dup_rmap(page, true);
4108	} else {
4109		ClearPagePrivate(page);
4110		hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
4111	}
4112
4113	_dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE);
4114	if (dst_vma->vm_flags & VM_WRITE)
4115		_dst_pte = huge_pte_mkdirty(_dst_pte);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4116	_dst_pte = pte_mkyoung(_dst_pte);
4117
 
 
 
4118	set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
4119
4120	(void)huge_ptep_set_access_flags(dst_vma, dst_addr, dst_pte, _dst_pte,
4121					dst_vma->vm_flags & VM_WRITE);
4122	hugetlb_count_add(pages_per_huge_page(h), dst_mm);
4123
4124	/* No need to invalidate - it was non-present before */
4125	update_mmu_cache(dst_vma, dst_addr, dst_pte);
4126
4127	spin_unlock(ptl);
4128	if (vm_shared)
 
 
4129		unlock_page(page);
4130	ret = 0;
4131out:
4132	return ret;
4133out_release_unlock:
4134	spin_unlock(ptl);
4135	if (vm_shared)
4136		unlock_page(page);
4137out_release_nounlock:
 
 
4138	put_page(page);
4139	goto out;
4140}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4141
4142long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
4143			 struct page **pages, struct vm_area_struct **vmas,
4144			 unsigned long *position, unsigned long *nr_pages,
4145			 long i, unsigned int flags, int *nonblocking)
4146{
4147	unsigned long pfn_offset;
4148	unsigned long vaddr = *position;
4149	unsigned long remainder = *nr_pages;
4150	struct hstate *h = hstate_vma(vma);
4151	int err = -EFAULT;
4152
4153	while (vaddr < vma->vm_end && remainder) {
4154		pte_t *pte;
4155		spinlock_t *ptl = NULL;
 
4156		int absent;
4157		struct page *page;
4158
4159		/*
4160		 * If we have a pending SIGKILL, don't keep faulting pages and
4161		 * potentially allocating memory.
4162		 */
4163		if (unlikely(fatal_signal_pending(current))) {
4164			remainder = 0;
4165			break;
4166		}
4167
4168		/*
4169		 * Some archs (sparc64, sh*) have multiple pte_ts to
4170		 * each hugepage.  We have to make sure we get the
4171		 * first, for the page indexing below to work.
4172		 *
4173		 * Note that page table lock is not held when pte is null.
4174		 */
4175		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h),
4176				      huge_page_size(h));
4177		if (pte)
4178			ptl = huge_pte_lock(h, mm, pte);
4179		absent = !pte || huge_pte_none(huge_ptep_get(pte));
4180
4181		/*
4182		 * When coredumping, it suits get_dump_page if we just return
4183		 * an error where there's an empty slot with no huge pagecache
4184		 * to back it.  This way, we avoid allocating a hugepage, and
4185		 * the sparse dumpfile avoids allocating disk blocks, but its
4186		 * huge holes still show up with zeroes where they need to be.
4187		 */
4188		if (absent && (flags & FOLL_DUMP) &&
4189		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
4190			if (pte)
4191				spin_unlock(ptl);
4192			remainder = 0;
4193			break;
4194		}
4195
4196		/*
4197		 * We need call hugetlb_fault for both hugepages under migration
4198		 * (in which case hugetlb_fault waits for the migration,) and
4199		 * hwpoisoned hugepages (in which case we need to prevent the
4200		 * caller from accessing to them.) In order to do this, we use
4201		 * here is_swap_pte instead of is_hugetlb_entry_migration and
4202		 * is_hugetlb_entry_hwpoisoned. This is because it simply covers
4203		 * both cases, and because we can't follow correct pages
4204		 * directly from any kind of swap entries.
4205		 */
4206		if (absent || is_swap_pte(huge_ptep_get(pte)) ||
4207		    ((flags & FOLL_WRITE) &&
4208		      !huge_pte_write(huge_ptep_get(pte)))) {
4209			int ret;
4210			unsigned int fault_flags = 0;
4211
4212			if (pte)
4213				spin_unlock(ptl);
4214			if (flags & FOLL_WRITE)
4215				fault_flags |= FAULT_FLAG_WRITE;
4216			if (nonblocking)
4217				fault_flags |= FAULT_FLAG_ALLOW_RETRY;
 
 
 
 
 
 
4218			if (flags & FOLL_NOWAIT)
4219				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
4220					FAULT_FLAG_RETRY_NOWAIT;
4221			if (flags & FOLL_TRIED) {
4222				VM_WARN_ON_ONCE(fault_flags &
4223						FAULT_FLAG_ALLOW_RETRY);
 
 
4224				fault_flags |= FAULT_FLAG_TRIED;
4225			}
4226			ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
4227			if (ret & VM_FAULT_ERROR) {
4228				err = vm_fault_to_errno(ret, flags);
4229				remainder = 0;
4230				break;
4231			}
4232			if (ret & VM_FAULT_RETRY) {
4233				if (nonblocking)
4234					*nonblocking = 0;
 
4235				*nr_pages = 0;
4236				/*
4237				 * VM_FAULT_RETRY must not return an
4238				 * error, it will return zero
4239				 * instead.
4240				 *
4241				 * No need to update "position" as the
4242				 * caller will not check it after
4243				 * *nr_pages is set to 0.
4244				 */
4245				return i;
4246			}
4247			continue;
4248		}
4249
4250		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
4251		page = pte_page(huge_ptep_get(pte));
4252same_page:
4253		if (pages) {
4254			pages[i] = mem_map_offset(page, pfn_offset);
4255			get_page(pages[i]);
 
 
 
 
 
 
 
 
 
 
 
 
4256		}
4257
4258		if (vmas)
4259			vmas[i] = vma;
 
 
 
 
 
 
 
4260
4261		vaddr += PAGE_SIZE;
4262		++pfn_offset;
4263		--remainder;
4264		++i;
4265		if (vaddr < vma->vm_end && remainder &&
4266				pfn_offset < pages_per_huge_page(h)) {
4267			/*
4268			 * We use pfn_offset to avoid touching the pageframes
4269			 * of this compound page.
 
 
 
 
 
 
 
 
4270			 */
4271			goto same_page;
 
 
 
 
 
 
4272		}
 
 
 
 
 
4273		spin_unlock(ptl);
4274	}
4275	*nr_pages = remainder;
4276	/*
4277	 * setting position is actually required only if remainder is
4278	 * not zero but it's faster not to add a "if (remainder)"
4279	 * branch.
4280	 */
4281	*position = vaddr;
4282
4283	return i ? i : err;
4284}
4285
4286#ifndef __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
4287/*
4288 * ARCHes with special requirements for evicting HUGETLB backing TLB entries can
4289 * implement this.
4290 */
4291#define flush_hugetlb_tlb_range(vma, addr, end)	flush_tlb_range(vma, addr, end)
4292#endif
4293
4294unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
4295		unsigned long address, unsigned long end, pgprot_t newprot)
 
4296{
4297	struct mm_struct *mm = vma->vm_mm;
4298	unsigned long start = address;
4299	pte_t *ptep;
4300	pte_t pte;
4301	struct hstate *h = hstate_vma(vma);
4302	unsigned long pages = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4303
4304	BUG_ON(address >= end);
4305	flush_cache_range(vma, address, end);
4306
4307	mmu_notifier_invalidate_range_start(mm, start, end);
 
4308	i_mmap_lock_write(vma->vm_file->f_mapping);
4309	for (; address < end; address += huge_page_size(h)) {
 
4310		spinlock_t *ptl;
4311		ptep = huge_pte_offset(mm, address, huge_page_size(h));
4312		if (!ptep)
4313			continue;
 
 
 
 
 
 
 
 
 
 
 
4314		ptl = huge_pte_lock(h, mm, ptep);
4315		if (huge_pmd_unshare(mm, &address, ptep)) {
 
 
 
 
 
 
4316			pages++;
4317			spin_unlock(ptl);
 
 
4318			continue;
4319		}
4320		pte = huge_ptep_get(ptep);
4321		if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
4322			spin_unlock(ptl);
4323			continue;
4324		}
4325		if (unlikely(is_hugetlb_entry_migration(pte))) {
4326			swp_entry_t entry = pte_to_swp_entry(pte);
 
 
4327
4328			if (is_write_migration_entry(entry)) {
4329				pte_t newpte;
4330
4331				make_migration_entry_read(&entry);
 
 
 
4332				newpte = swp_entry_to_pte(entry);
4333				set_huge_swap_pte_at(mm, address, ptep,
4334						     newpte, huge_page_size(h));
4335				pages++;
4336			}
4337			spin_unlock(ptl);
4338			continue;
4339		}
4340		if (!huge_pte_none(pte)) {
4341			pte = huge_ptep_get_and_clear(mm, address, ptep);
4342			pte = pte_mkhuge(huge_pte_modify(pte, newprot));
4343			pte = arch_make_huge_pte(pte, vma, NULL, 0);
4344			set_huge_pte_at(mm, address, ptep, pte);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4345			pages++;
 
 
 
 
 
 
4346		}
4347		spin_unlock(ptl);
4348	}
4349	/*
4350	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
4351	 * may have cleared our pud entry and done put_page on the page table:
4352	 * once we release i_mmap_rwsem, another task can do the final put_page
4353	 * and that page table be reused and filled with junk.
 
4354	 */
4355	flush_hugetlb_tlb_range(vma, start, end);
 
 
 
4356	/*
4357	 * No need to call mmu_notifier_invalidate_range() we are downgrading
4358	 * page table protection not changing it to point to a new page.
4359	 *
4360	 * See Documentation/vm/mmu_notifier.txt
4361	 */
4362	i_mmap_unlock_write(vma->vm_file->f_mapping);
4363	mmu_notifier_invalidate_range_end(mm, start, end);
 
4364
4365	return pages << h->order;
4366}
4367
4368int hugetlb_reserve_pages(struct inode *inode,
 
4369					long from, long to,
4370					struct vm_area_struct *vma,
4371					vm_flags_t vm_flags)
4372{
4373	long ret, chg;
4374	struct hstate *h = hstate_inode(inode);
4375	struct hugepage_subpool *spool = subpool_inode(inode);
4376	struct resv_map *resv_map;
4377	long gbl_reserve;
 
4378
4379	/* This should never happen */
4380	if (from > to) {
4381		VM_WARN(1, "%s called with a negative range\n", __func__);
4382		return -EINVAL;
4383	}
4384
4385	/*
 
 
 
 
 
 
4386	 * Only apply hugepage reservation if asked. At fault time, an
4387	 * attempt will be made for VM_NORESERVE to allocate a page
4388	 * without using reserves
4389	 */
4390	if (vm_flags & VM_NORESERVE)
4391		return 0;
4392
4393	/*
4394	 * Shared mappings base their reservation on the number of pages that
4395	 * are already allocated on behalf of the file. Private mappings need
4396	 * to reserve the full area even if read-only as mprotect() may be
4397	 * called to make the mapping read-write. Assume !vma is a shm mapping
4398	 */
4399	if (!vma || vma->vm_flags & VM_MAYSHARE) {
 
 
 
 
 
4400		resv_map = inode_resv_map(inode);
4401
4402		chg = region_chg(resv_map, from, to);
4403
4404	} else {
 
4405		resv_map = resv_map_alloc();
4406		if (!resv_map)
4407			return -ENOMEM;
4408
4409		chg = to - from;
4410
4411		set_vma_resv_map(vma, resv_map);
4412		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
4413	}
4414
4415	if (chg < 0) {
4416		ret = chg;
 
 
 
4417		goto out_err;
 
 
 
 
 
 
4418	}
4419
4420	/*
4421	 * There must be enough pages in the subpool for the mapping. If
4422	 * the subpool has a minimum size, there may be some global
4423	 * reservations already in place (gbl_reserve).
4424	 */
4425	gbl_reserve = hugepage_subpool_get_pages(spool, chg);
4426	if (gbl_reserve < 0) {
4427		ret = -ENOSPC;
4428		goto out_err;
4429	}
4430
4431	/*
4432	 * Check enough hugepages are available for the reservation.
4433	 * Hand the pages back to the subpool if there are not
4434	 */
4435	ret = hugetlb_acct_memory(h, gbl_reserve);
4436	if (ret < 0) {
4437		/* put back original number of pages, chg */
4438		(void)hugepage_subpool_put_pages(spool, chg);
4439		goto out_err;
4440	}
4441
4442	/*
4443	 * Account for the reservations made. Shared mappings record regions
4444	 * that have reservations as they are shared by multiple VMAs.
4445	 * When the last VMA disappears, the region map says how much
4446	 * the reservation was and the page cache tells how much of
4447	 * the reservation was consumed. Private mappings are per-VMA and
4448	 * only the consumed reservations are tracked. When the VMA
4449	 * disappears, the original reservation is the VMA size and the
4450	 * consumed reservations are stored in the map. Hence, nothing
4451	 * else has to be done for private mappings here
4452	 */
4453	if (!vma || vma->vm_flags & VM_MAYSHARE) {
4454		long add = region_add(resv_map, from, to);
4455
4456		if (unlikely(chg > add)) {
 
 
 
4457			/*
4458			 * pages in this range were added to the reserve
4459			 * map between region_chg and region_add.  This
4460			 * indicates a race with alloc_huge_page.  Adjust
4461			 * the subpool and reserve counts modified above
4462			 * based on the difference.
4463			 */
4464			long rsv_adjust;
4465
 
 
 
 
 
 
 
 
4466			rsv_adjust = hugepage_subpool_put_pages(spool,
4467								chg - add);
4468			hugetlb_acct_memory(h, -rsv_adjust);
 
 
 
 
 
 
 
 
4469		}
4470	}
4471	return 0;
 
 
 
 
 
 
 
4472out_err:
 
4473	if (!vma || vma->vm_flags & VM_MAYSHARE)
4474		/* Don't call region_abort if region_chg failed */
4475		if (chg >= 0)
4476			region_abort(resv_map, from, to);
 
 
4477	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
4478		kref_put(&resv_map->refs, resv_map_release);
4479	return ret;
4480}
4481
4482long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
4483								long freed)
4484{
4485	struct hstate *h = hstate_inode(inode);
4486	struct resv_map *resv_map = inode_resv_map(inode);
4487	long chg = 0;
4488	struct hugepage_subpool *spool = subpool_inode(inode);
4489	long gbl_reserve;
4490
 
 
 
 
4491	if (resv_map) {
4492		chg = region_del(resv_map, start, end);
4493		/*
4494		 * region_del() can fail in the rare case where a region
4495		 * must be split and another region descriptor can not be
4496		 * allocated.  If end == LONG_MAX, it will not fail.
4497		 */
4498		if (chg < 0)
4499			return chg;
4500	}
4501
4502	spin_lock(&inode->i_lock);
4503	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
4504	spin_unlock(&inode->i_lock);
4505
4506	/*
4507	 * If the subpool has a minimum size, the number of global
4508	 * reservations to be released may be adjusted.
 
 
 
4509	 */
4510	gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed));
4511	hugetlb_acct_memory(h, -gbl_reserve);
4512
4513	return 0;
4514}
4515
4516#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
4517static unsigned long page_table_shareable(struct vm_area_struct *svma,
4518				struct vm_area_struct *vma,
4519				unsigned long addr, pgoff_t idx)
4520{
4521	unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
4522				svma->vm_start;
4523	unsigned long sbase = saddr & PUD_MASK;
4524	unsigned long s_end = sbase + PUD_SIZE;
4525
4526	/* Allow segments to share if only one is marked locked */
4527	unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
4528	unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
4529
4530	/*
4531	 * match the virtual addresses, permission and the alignment of the
4532	 * page table page.
 
 
4533	 */
4534	if (pmd_index(addr) != pmd_index(saddr) ||
4535	    vm_flags != svm_flags ||
4536	    sbase < svma->vm_start || svma->vm_end < s_end)
 
4537		return 0;
4538
4539	return saddr;
4540}
4541
4542static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
4543{
4544	unsigned long base = addr & PUD_MASK;
4545	unsigned long end = base + PUD_SIZE;
4546
 
 
 
 
4547	/*
4548	 * check on proper vm_flags and page table alignment
4549	 */
4550	if (vma->vm_flags & VM_MAYSHARE &&
4551	    vma->vm_start <= base && end <= vma->vm_end)
4552		return true;
4553	return false;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4554}
4555
4556/*
4557 * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
4558 * and returns the corresponding pte. While this is not necessary for the
4559 * !shared pmd case because we can allocate the pmd later as well, it makes the
4560 * code much cleaner. pmd allocation is essential for the shared case because
4561 * pud has to be populated inside the same i_mmap_rwsem section - otherwise
4562 * racing tasks could either miss the sharing (see huge_pte_offset) or select a
4563 * bad pmd for sharing.
4564 */
4565pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
 
4566{
4567	struct vm_area_struct *vma = find_vma(mm, addr);
4568	struct address_space *mapping = vma->vm_file->f_mapping;
4569	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
4570			vma->vm_pgoff;
4571	struct vm_area_struct *svma;
4572	unsigned long saddr;
4573	pte_t *spte = NULL;
4574	pte_t *pte;
4575	spinlock_t *ptl;
4576
4577	if (!vma_shareable(vma, addr))
4578		return (pte_t *)pmd_alloc(mm, pud, addr);
4579
4580	i_mmap_lock_write(mapping);
4581	vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
4582		if (svma == vma)
4583			continue;
4584
4585		saddr = page_table_shareable(svma, vma, addr, idx);
4586		if (saddr) {
4587			spte = huge_pte_offset(svma->vm_mm, saddr,
4588					       vma_mmu_pagesize(svma));
4589			if (spte) {
4590				get_page(virt_to_page(spte));
4591				break;
4592			}
4593		}
4594	}
4595
4596	if (!spte)
4597		goto out;
4598
4599	ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
4600	if (pud_none(*pud)) {
4601		pud_populate(mm, pud,
4602				(pmd_t *)((unsigned long)spte & PAGE_MASK));
4603		mm_inc_nr_pmds(mm);
4604	} else {
4605		put_page(virt_to_page(spte));
4606	}
4607	spin_unlock(ptl);
4608out:
4609	pte = (pte_t *)pmd_alloc(mm, pud, addr);
4610	i_mmap_unlock_write(mapping);
4611	return pte;
4612}
4613
4614/*
4615 * unmap huge page backed by shared pte.
4616 *
4617 * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
4618 * indicated by page_count > 1, unmap is achieved by clearing pud and
4619 * decrementing the ref count. If count == 1, the pte page is not shared.
4620 *
4621 * called with page table lock held.
4622 *
4623 * returns: 1 successfully unmapped a shared pte page
4624 *	    0 the underlying pte page is not shared, or it is the last user
4625 */
4626int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 
4627{
4628	pgd_t *pgd = pgd_offset(mm, *addr);
4629	p4d_t *p4d = p4d_offset(pgd, *addr);
4630	pud_t *pud = pud_offset(p4d, *addr);
4631
 
 
4632	BUG_ON(page_count(virt_to_page(ptep)) == 0);
4633	if (page_count(virt_to_page(ptep)) == 1)
4634		return 0;
4635
4636	pud_clear(pud);
4637	put_page(virt_to_page(ptep));
4638	mm_dec_nr_pmds(mm);
4639	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
4640	return 1;
4641}
4642#define want_pmd_share()	(1)
4643#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4644pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
 
 
4645{
4646	return NULL;
4647}
4648
4649int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 
4650{
4651	return 0;
4652}
4653#define want_pmd_share()	(0)
 
 
 
 
 
 
 
 
 
4654#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
4655
4656#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
4657pte_t *huge_pte_alloc(struct mm_struct *mm,
4658			unsigned long addr, unsigned long sz)
4659{
4660	pgd_t *pgd;
4661	p4d_t *p4d;
4662	pud_t *pud;
4663	pte_t *pte = NULL;
4664
4665	pgd = pgd_offset(mm, addr);
4666	p4d = p4d_alloc(mm, pgd, addr);
4667	if (!p4d)
4668		return NULL;
4669	pud = pud_alloc(mm, p4d, addr);
4670	if (pud) {
4671		if (sz == PUD_SIZE) {
4672			pte = (pte_t *)pud;
4673		} else {
4674			BUG_ON(sz != PMD_SIZE);
4675			if (want_pmd_share() && pud_none(*pud))
4676				pte = huge_pmd_share(mm, addr, pud);
4677			else
4678				pte = (pte_t *)pmd_alloc(mm, pud, addr);
4679		}
4680	}
4681	BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte));
4682
4683	return pte;
4684}
4685
4686/*
4687 * huge_pte_offset() - Walk the page table to resolve the hugepage
4688 * entry at address @addr
4689 *
4690 * Return: Pointer to page table or swap entry (PUD or PMD) for
4691 * address @addr, or NULL if a p*d_none() entry is encountered and the
4692 * size @sz doesn't match the hugepage size at this level of the page
4693 * table.
4694 */
4695pte_t *huge_pte_offset(struct mm_struct *mm,
4696		       unsigned long addr, unsigned long sz)
4697{
4698	pgd_t *pgd;
4699	p4d_t *p4d;
4700	pud_t *pud;
4701	pmd_t *pmd;
4702
4703	pgd = pgd_offset(mm, addr);
4704	if (!pgd_present(*pgd))
4705		return NULL;
4706	p4d = p4d_offset(pgd, addr);
4707	if (!p4d_present(*p4d))
4708		return NULL;
4709
4710	pud = pud_offset(p4d, addr);
4711	if (sz != PUD_SIZE && pud_none(*pud))
4712		return NULL;
4713	/* hugepage or swap? */
4714	if (pud_huge(*pud) || !pud_present(*pud))
4715		return (pte_t *)pud;
4716
4717	pmd = pmd_offset(pud, addr);
4718	if (sz != PMD_SIZE && pmd_none(*pmd))
4719		return NULL;
4720	/* hugepage or swap? */
4721	if (pmd_huge(*pmd) || !pmd_present(*pmd))
4722		return (pte_t *)pmd;
4723
4724	return NULL;
 
 
4725}
4726
4727#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
4728
4729/*
4730 * These functions are overwritable if your architecture needs its own
4731 * behavior.
 
 
 
4732 */
4733struct page * __weak
4734follow_huge_addr(struct mm_struct *mm, unsigned long address,
4735			      int write)
4736{
4737	return ERR_PTR(-EINVAL);
4738}
4739
4740struct page * __weak
4741follow_huge_pd(struct vm_area_struct *vma,
4742	       unsigned long address, hugepd_t hpd, int flags, int pdshift)
4743{
4744	WARN(1, "hugepd follow called with no support for hugepage directory format\n");
4745	return NULL;
4746}
4747
4748struct page * __weak
4749follow_huge_pmd(struct mm_struct *mm, unsigned long address,
4750		pmd_t *pmd, int flags)
 
4751{
4752	struct page *page = NULL;
4753	spinlock_t *ptl;
4754	pte_t pte;
4755retry:
4756	ptl = pmd_lockptr(mm, pmd);
4757	spin_lock(ptl);
4758	/*
4759	 * make sure that the address range covered by this pmd is not
4760	 * unmapped from other threads.
4761	 */
4762	if (!pmd_huge(*pmd))
4763		goto out;
4764	pte = huge_ptep_get((pte_t *)pmd);
4765	if (pte_present(pte)) {
4766		page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
4767		if (flags & FOLL_GET)
4768			get_page(page);
4769	} else {
4770		if (is_hugetlb_entry_migration(pte)) {
4771			spin_unlock(ptl);
4772			__migration_entry_wait(mm, (pte_t *)pmd, ptl);
4773			goto retry;
4774		}
4775		/*
4776		 * hwpoisoned entry is treated as no_page_table in
4777		 * follow_page_mask().
4778		 */
4779	}
4780out:
4781	spin_unlock(ptl);
4782	return page;
4783}
4784
4785struct page * __weak
4786follow_huge_pud(struct mm_struct *mm, unsigned long address,
4787		pud_t *pud, int flags)
 
 
 
 
4788{
4789	if (flags & FOLL_GET)
4790		return NULL;
4791
4792	return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
 
 
 
 
 
 
 
 
 
 
 
4793}
4794
4795struct page * __weak
4796follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int flags)
4797{
4798	if (flags & FOLL_GET)
4799		return NULL;
4800
4801	return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT);
 
 
 
 
 
 
 
 
 
 
 
 
4802}
4803
4804bool isolate_huge_page(struct page *page, struct list_head *list)
 
4805{
4806	bool ret = true;
4807
4808	VM_BUG_ON_PAGE(!PageHead(page), page);
4809	spin_lock(&hugetlb_lock);
4810	if (!page_huge_active(page) || !get_page_unless_zero(page)) {
4811		ret = false;
4812		goto unlock;
4813	}
4814	clear_page_huge_active(page);
4815	list_move_tail(&page->lru, list);
4816unlock:
4817	spin_unlock(&hugetlb_lock);
4818	return ret;
4819}
4820
4821void putback_active_hugepage(struct page *page)
4822{
4823	VM_BUG_ON_PAGE(!PageHead(page), page);
4824	spin_lock(&hugetlb_lock);
4825	set_page_huge_active(page);
4826	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
4827	spin_unlock(&hugetlb_lock);
4828	put_page(page);
4829}
4830
4831void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason)
4832{
4833	struct hstate *h = page_hstate(oldpage);
4834
4835	hugetlb_cgroup_migrate(oldpage, newpage);
4836	set_page_owner_migrate_reason(newpage, reason);
4837
4838	/*
4839	 * transfer temporary state of the new huge page. This is
4840	 * reverse to other transitions because the newpage is going to
4841	 * be final while the old one will be freed so it takes over
4842	 * the temporary status.
4843	 *
4844	 * Also note that we have to transfer the per-node surplus state
4845	 * here as well otherwise the global surplus count will not match
4846	 * the per-node's.
4847	 */
4848	if (PageHugeTemporary(newpage)) {
4849		int old_nid = page_to_nid(oldpage);
4850		int new_nid = page_to_nid(newpage);
 
 
 
4851
4852		SetPageHugeTemporary(oldpage);
4853		ClearPageHugeTemporary(newpage);
4854
4855		spin_lock(&hugetlb_lock);
 
 
 
 
 
 
4856		if (h->surplus_huge_pages_node[old_nid]) {
4857			h->surplus_huge_pages_node[old_nid]--;
4858			h->surplus_huge_pages_node[new_nid]++;
4859		}
4860		spin_unlock(&hugetlb_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4861	}
 
 
4862}