1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *	linux/mm/madvise.c
   4 *
   5 * Copyright (C) 1999  Linus Torvalds
   6 * Copyright (C) 2002  Christoph Hellwig
   7 */
   8
   9#include <linux/mman.h>
  10#include <linux/pagemap.h>
  11#include <linux/syscalls.h>
  12#include <linux/mempolicy.h>
  13#include <linux/page-isolation.h>
  14#include <linux/page_idle.h>
  15#include <linux/userfaultfd_k.h>
  16#include <linux/hugetlb.h>
  17#include <linux/falloc.h>
  18#include <linux/fadvise.h>
  19#include <linux/sched.h>
  20#include <linux/sched/mm.h>
  21#include <linux/mm_inline.h>
  22#include <linux/string.h>
  23#include <linux/uio.h>
  24#include <linux/ksm.h>
  25#include <linux/fs.h>
  26#include <linux/file.h>
  27#include <linux/blkdev.h>
  28#include <linux/backing-dev.h>
  29#include <linux/pagewalk.h>
  30#include <linux/swap.h>
  31#include <linux/swapops.h>
  32#include <linux/shmem_fs.h>
  33#include <linux/mmu_notifier.h>
  34
  35#include <asm/tlb.h>
  36
  37#include "internal.h"
  38#include "swap.h"
  39
  40struct madvise_walk_private {
  41	struct mmu_gather *tlb;
  42	bool pageout;
  43};
  44
  45/*
  46 * Any behaviour which results in changes to the vma->vm_flags needs to
  47 * take mmap_lock for writing. Others, which simply traverse vmas, need
  48 * to only take it for reading.
  49 */
  50static int madvise_need_mmap_write(int behavior)
  51{
  52	switch (behavior) {
  53	case MADV_REMOVE:
  54	case MADV_WILLNEED:
  55	case MADV_DONTNEED:
  56	case MADV_DONTNEED_LOCKED:
  57	case MADV_COLD:
  58	case MADV_PAGEOUT:
  59	case MADV_FREE:
  60	case MADV_POPULATE_READ:
  61	case MADV_POPULATE_WRITE:
  62	case MADV_COLLAPSE:
  63		return 0;
  64	default:
  65		/* be safe, default to 1. list exceptions explicitly */
  66		return 1;
  67	}
  68}
  69
  70#ifdef CONFIG_ANON_VMA_NAME
  71struct anon_vma_name *anon_vma_name_alloc(const char *name)
  72{
  73	struct anon_vma_name *anon_name;
  74	size_t count;
  75
  76	/* Add 1 for NUL terminator at the end of the anon_name->name */
  77	count = strlen(name) + 1;
  78	anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
  79	if (anon_name) {
  80		kref_init(&anon_name->kref);
  81		memcpy(anon_name->name, name, count);
  82	}
  83
  84	return anon_name;
  85}
  86
  87void anon_vma_name_free(struct kref *kref)
  88{
  89	struct anon_vma_name *anon_name =
  90			container_of(kref, struct anon_vma_name, kref);
  91	kfree(anon_name);
  92}
  93
  94struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
  95{
  96	mmap_assert_locked(vma->vm_mm);
  97
  98	return vma->anon_name;
  99}
 100
 101/* mmap_lock should be write-locked */
 102static int replace_anon_vma_name(struct vm_area_struct *vma,
 103				 struct anon_vma_name *anon_name)
 104{
 105	struct anon_vma_name *orig_name = anon_vma_name(vma);
 106
 107	if (!anon_name) {
 108		vma->anon_name = NULL;
 109		anon_vma_name_put(orig_name);
 110		return 0;
 111	}
 112
 113	if (anon_vma_name_eq(orig_name, anon_name))
 114		return 0;
 115
 116	vma->anon_name = anon_vma_name_reuse(anon_name);
 117	anon_vma_name_put(orig_name);
 118
 119	return 0;
 120}
 121#else /* CONFIG_ANON_VMA_NAME */
 122static int replace_anon_vma_name(struct vm_area_struct *vma,
 123				 struct anon_vma_name *anon_name)
 124{
 125	if (anon_name)
 126		return -EINVAL;
 127
 128	return 0;
 129}
 130#endif /* CONFIG_ANON_VMA_NAME */
 131/*
 132 * Update the vm_flags on region of a vma, splitting it or merging it as
 133 * necessary.  Must be called with mmap_lock held for writing;
 134 * Caller should ensure anon_name stability by raising its refcount even when
 135 * anon_name belongs to a valid vma because this function might free that vma.
 136 */
 137static int madvise_update_vma(struct vm_area_struct *vma,
 138			      struct vm_area_struct **prev, unsigned long start,
 139			      unsigned long end, unsigned long new_flags,
 140			      struct anon_vma_name *anon_name)
 141{
 142	struct mm_struct *mm = vma->vm_mm;
 143	int error;
 144	VMA_ITERATOR(vmi, mm, start);
 
 145
 146	if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 147		*prev = vma;
 148		return 0;
 149	}
 150
 151	vma = vma_modify_flags_name(&vmi, *prev, vma, start, end, new_flags,
 152				    anon_name);
 153	if (IS_ERR(vma))
 154		return PTR_ERR(vma);
 
 
 
 155
 156	*prev = vma;
 157
 158	/* vm_flags is protected by the mmap_lock held in write mode. */
 159	vma_start_write(vma);
 160	vm_flags_reset(vma, new_flags);
 161	if (!vma->vm_file || vma_is_anon_shmem(vma)) {
 162		error = replace_anon_vma_name(vma, anon_name);
 163		if (error)
 164			return error;
 165	}
 166
 167	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 168}
 169
 170#ifdef CONFIG_SWAP
 171static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
 172		unsigned long end, struct mm_walk *walk)
 173{
 
 174	struct vm_area_struct *vma = walk->private;
 175	struct swap_iocb *splug = NULL;
 176	pte_t *ptep = NULL;
 177	spinlock_t *ptl;
 178	unsigned long addr;
 179
 180	for (addr = start; addr < end; addr += PAGE_SIZE) {
 181		pte_t pte;
 182		swp_entry_t entry;
 183		struct folio *folio;
 
 184
 185		if (!ptep++) {
 186			ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 187			if (!ptep)
 188				break;
 189		}
 190
 191		pte = ptep_get(ptep);
 192		if (!is_swap_pte(pte))
 193			continue;
 194		entry = pte_to_swp_entry(pte);
 195		if (unlikely(non_swap_entry(entry)))
 196			continue;
 197
 198		pte_unmap_unlock(ptep, ptl);
 199		ptep = NULL;
 200
 201		folio = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
 202					     vma, addr, &splug);
 203		if (folio)
 204			folio_put(folio);
 205	}
 206
 207	if (ptep)
 208		pte_unmap_unlock(ptep, ptl);
 209	swap_read_unplug(splug);
 210	cond_resched();
 211
 212	return 0;
 213}
 214
 215static const struct mm_walk_ops swapin_walk_ops = {
 216	.pmd_entry		= swapin_walk_pmd_entry,
 217	.walk_lock		= PGWALK_RDLOCK,
 218};
 
 
 
 
 
 
 
 
 
 219
 220static void shmem_swapin_range(struct vm_area_struct *vma,
 221		unsigned long start, unsigned long end,
 222		struct address_space *mapping)
 223{
 224	XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
 225	pgoff_t end_index = linear_page_index(vma, end) - 1;
 226	struct folio *folio;
 227	struct swap_iocb *splug = NULL;
 228
 229	rcu_read_lock();
 230	xas_for_each(&xas, folio, end_index) {
 231		unsigned long addr;
 232		swp_entry_t entry;
 233
 234		if (!xa_is_value(folio))
 235			continue;
 236		entry = radix_to_swp_entry(folio);
 237		/* There might be swapin error entries in shmem mapping. */
 238		if (non_swap_entry(entry))
 239			continue;
 240
 241		addr = vma->vm_start +
 242			((xas.xa_index - vma->vm_pgoff) << PAGE_SHIFT);
 243		xas_pause(&xas);
 244		rcu_read_unlock();
 245
 246		folio = read_swap_cache_async(entry, mapping_gfp_mask(mapping),
 247					     vma, addr, &splug);
 248		if (folio)
 249			folio_put(folio);
 250
 251		rcu_read_lock();
 
 
 
 
 
 
 
 
 
 
 252	}
 253	rcu_read_unlock();
 254	swap_read_unplug(splug);
 255}
 256#endif		/* CONFIG_SWAP */
 257
 258/*
 259 * Schedule all required I/O operations.  Do not wait for completion.
 260 */
 261static long madvise_willneed(struct vm_area_struct *vma,
 262			     struct vm_area_struct **prev,
 263			     unsigned long start, unsigned long end)
 264{
 265	struct mm_struct *mm = vma->vm_mm;
 266	struct file *file = vma->vm_file;
 267	loff_t offset;
 268
 269	*prev = vma;
 270#ifdef CONFIG_SWAP
 271	if (!file) {
 272		walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
 273		lru_add_drain(); /* Push any new pages onto the LRU now */
 
 
 
 
 274		return 0;
 275	}
 
 276
 277	if (shmem_mapping(file->f_mapping)) {
 278		shmem_swapin_range(vma, start, end, file->f_mapping);
 279		lru_add_drain(); /* Push any new pages onto the LRU now */
 280		return 0;
 281	}
 282#else
 283	if (!file)
 284		return -EBADF;
 285#endif
 286
 287	if (IS_DAX(file_inode(file))) {
 288		/* no bad return value, but ignore advice */
 289		return 0;
 290	}
 291
 292	/*
 293	 * Filesystem's fadvise may need to take various locks.  We need to
 294	 * explicitly grab a reference because the vma (and hence the
 295	 * vma's reference to the file) can go away as soon as we drop
 296	 * mmap_lock.
 297	 */
 298	*prev = NULL;	/* tell sys_madvise we drop mmap_lock */
 299	get_file(file);
 300	offset = (loff_t)(start - vma->vm_start)
 301			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 302	mmap_read_unlock(mm);
 303	vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
 304	fput(file);
 305	mmap_read_lock(mm);
 306	return 0;
 307}
 308
 309static inline bool can_do_file_pageout(struct vm_area_struct *vma)
 310{
 311	if (!vma->vm_file)
 312		return false;
 313	/*
 314	 * paging out pagecache only for non-anonymous mappings that correspond
 315	 * to the files the calling process could (if tried) open for writing;
 316	 * otherwise we'd be including shared non-exclusive mappings, which
 317	 * opens a side channel.
 318	 */
 319	return inode_owner_or_capable(&nop_mnt_idmap,
 320				      file_inode(vma->vm_file)) ||
 321	       file_permission(vma->vm_file, MAY_WRITE) == 0;
 322}
 323
 324static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 325				unsigned long addr, unsigned long end,
 326				struct mm_walk *walk)
 327{
 328	struct madvise_walk_private *private = walk->private;
 329	struct mmu_gather *tlb = private->tlb;
 330	bool pageout = private->pageout;
 331	struct mm_struct *mm = tlb->mm;
 332	struct vm_area_struct *vma = walk->vma;
 333	pte_t *start_pte, *pte, ptent;
 334	spinlock_t *ptl;
 335	struct folio *folio = NULL;
 336	LIST_HEAD(folio_list);
 337	bool pageout_anon_only_filter;
 338	unsigned int batch_count = 0;
 339
 340	if (fatal_signal_pending(current))
 341		return -EINTR;
 342
 343	pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
 344					!can_do_file_pageout(vma);
 345
 346#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 347	if (pmd_trans_huge(*pmd)) {
 348		pmd_t orig_pmd;
 349		unsigned long next = pmd_addr_end(addr, end);
 350
 351		tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
 352		ptl = pmd_trans_huge_lock(pmd, vma);
 353		if (!ptl)
 354			return 0;
 355
 356		orig_pmd = *pmd;
 357		if (is_huge_zero_pmd(orig_pmd))
 358			goto huge_unlock;
 359
 360		if (unlikely(!pmd_present(orig_pmd))) {
 361			VM_BUG_ON(thp_migration_supported() &&
 362					!is_pmd_migration_entry(orig_pmd));
 363			goto huge_unlock;
 364		}
 365
 366		folio = pfn_folio(pmd_pfn(orig_pmd));
 367
 368		/* Do not interfere with other mappings of this folio */
 369		if (folio_estimated_sharers(folio) != 1)
 370			goto huge_unlock;
 371
 372		if (pageout_anon_only_filter && !folio_test_anon(folio))
 373			goto huge_unlock;
 374
 375		if (next - addr != HPAGE_PMD_SIZE) {
 376			int err;
 377
 378			folio_get(folio);
 379			spin_unlock(ptl);
 380			folio_lock(folio);
 381			err = split_folio(folio);
 382			folio_unlock(folio);
 383			folio_put(folio);
 384			if (!err)
 385				goto regular_folio;
 386			return 0;
 387		}
 388
 389		if (pmd_young(orig_pmd)) {
 390			pmdp_invalidate(vma, addr, pmd);
 391			orig_pmd = pmd_mkold(orig_pmd);
 392
 393			set_pmd_at(mm, addr, pmd, orig_pmd);
 394			tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
 395		}
 396
 397		folio_clear_referenced(folio);
 398		folio_test_clear_young(folio);
 399		if (folio_test_active(folio))
 400			folio_set_workingset(folio);
 401		if (pageout) {
 402			if (folio_isolate_lru(folio)) {
 403				if (folio_test_unevictable(folio))
 404					folio_putback_lru(folio);
 405				else
 406					list_add(&folio->lru, &folio_list);
 407			}
 408		} else
 409			folio_deactivate(folio);
 410huge_unlock:
 411		spin_unlock(ptl);
 412		if (pageout)
 413			reclaim_pages(&folio_list);
 414		return 0;
 415	}
 416
 417regular_folio:
 418#endif
 419	tlb_change_page_size(tlb, PAGE_SIZE);
 420restart:
 421	start_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 422	if (!start_pte)
 423		return 0;
 424	flush_tlb_batched_pending(mm);
 425	arch_enter_lazy_mmu_mode();
 426	for (; addr < end; pte++, addr += PAGE_SIZE) {
 427		ptent = ptep_get(pte);
 428
 429		if (++batch_count == SWAP_CLUSTER_MAX) {
 430			batch_count = 0;
 431			if (need_resched()) {
 432				arch_leave_lazy_mmu_mode();
 433				pte_unmap_unlock(start_pte, ptl);
 434				cond_resched();
 435				goto restart;
 436			}
 437		}
 438
 439		if (pte_none(ptent))
 440			continue;
 441
 442		if (!pte_present(ptent))
 443			continue;
 444
 445		folio = vm_normal_folio(vma, addr, ptent);
 446		if (!folio || folio_is_zone_device(folio))
 447			continue;
 448
 449		/*
 450		 * Creating a THP page is expensive so split it only if we
 451		 * are sure it's worth. Split it if we are only owner.
 452		 */
 453		if (folio_test_large(folio)) {
 454			int err;
 455
 456			if (folio_estimated_sharers(folio) != 1)
 457				break;
 458			if (pageout_anon_only_filter && !folio_test_anon(folio))
 459				break;
 460			if (!folio_trylock(folio))
 461				break;
 462			folio_get(folio);
 463			arch_leave_lazy_mmu_mode();
 464			pte_unmap_unlock(start_pte, ptl);
 465			start_pte = NULL;
 466			err = split_folio(folio);
 467			folio_unlock(folio);
 468			folio_put(folio);
 469			if (err)
 470				break;
 471			start_pte = pte =
 472				pte_offset_map_lock(mm, pmd, addr, &ptl);
 473			if (!start_pte)
 474				break;
 475			arch_enter_lazy_mmu_mode();
 476			pte--;
 477			addr -= PAGE_SIZE;
 478			continue;
 479		}
 480
 481		/*
 482		 * Do not interfere with other mappings of this folio and
 483		 * non-LRU folio.
 484		 */
 485		if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
 486			continue;
 487
 488		if (pageout_anon_only_filter && !folio_test_anon(folio))
 489			continue;
 490
 491		VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
 492
 493		if (pte_young(ptent)) {
 494			ptent = ptep_get_and_clear_full(mm, addr, pte,
 495							tlb->fullmm);
 496			ptent = pte_mkold(ptent);
 497			set_pte_at(mm, addr, pte, ptent);
 498			tlb_remove_tlb_entry(tlb, pte, addr);
 499		}
 500
 501		/*
 502		 * We are deactivating a folio for accelerating reclaiming.
 503		 * VM couldn't reclaim the folio unless we clear PG_young.
 504		 * As a side effect, it makes confuse idle-page tracking
 505		 * because they will miss recent referenced history.
 506		 */
 507		folio_clear_referenced(folio);
 508		folio_test_clear_young(folio);
 509		if (folio_test_active(folio))
 510			folio_set_workingset(folio);
 511		if (pageout) {
 512			if (folio_isolate_lru(folio)) {
 513				if (folio_test_unevictable(folio))
 514					folio_putback_lru(folio);
 515				else
 516					list_add(&folio->lru, &folio_list);
 517			}
 518		} else
 519			folio_deactivate(folio);
 520	}
 521
 522	if (start_pte) {
 523		arch_leave_lazy_mmu_mode();
 524		pte_unmap_unlock(start_pte, ptl);
 525	}
 526	if (pageout)
 527		reclaim_pages(&folio_list);
 528	cond_resched();
 529
 530	return 0;
 531}
 532
 533static const struct mm_walk_ops cold_walk_ops = {
 534	.pmd_entry = madvise_cold_or_pageout_pte_range,
 535	.walk_lock = PGWALK_RDLOCK,
 536};
 537
 538static void madvise_cold_page_range(struct mmu_gather *tlb,
 539			     struct vm_area_struct *vma,
 540			     unsigned long addr, unsigned long end)
 541{
 542	struct madvise_walk_private walk_private = {
 543		.pageout = false,
 544		.tlb = tlb,
 545	};
 546
 547	tlb_start_vma(tlb, vma);
 548	walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
 549	tlb_end_vma(tlb, vma);
 550}
 551
 552static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
 553{
 554	return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
 555}
 556
 557static long madvise_cold(struct vm_area_struct *vma,
 558			struct vm_area_struct **prev,
 559			unsigned long start_addr, unsigned long end_addr)
 560{
 561	struct mm_struct *mm = vma->vm_mm;
 562	struct mmu_gather tlb;
 563
 564	*prev = vma;
 565	if (!can_madv_lru_vma(vma))
 566		return -EINVAL;
 567
 568	lru_add_drain();
 569	tlb_gather_mmu(&tlb, mm);
 570	madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
 571	tlb_finish_mmu(&tlb);
 572
 573	return 0;
 574}
 575
 576static void madvise_pageout_page_range(struct mmu_gather *tlb,
 577			     struct vm_area_struct *vma,
 578			     unsigned long addr, unsigned long end)
 579{
 580	struct madvise_walk_private walk_private = {
 581		.pageout = true,
 582		.tlb = tlb,
 583	};
 584
 585	tlb_start_vma(tlb, vma);
 586	walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
 587	tlb_end_vma(tlb, vma);
 588}
 589
 590static long madvise_pageout(struct vm_area_struct *vma,
 591			struct vm_area_struct **prev,
 592			unsigned long start_addr, unsigned long end_addr)
 593{
 594	struct mm_struct *mm = vma->vm_mm;
 595	struct mmu_gather tlb;
 596
 597	*prev = vma;
 598	if (!can_madv_lru_vma(vma))
 599		return -EINVAL;
 600
 601	/*
 602	 * If the VMA belongs to a private file mapping, there can be private
 603	 * dirty pages which can be paged out if even this process is neither
 604	 * owner nor write capable of the file. We allow private file mappings
 605	 * further to pageout dirty anon pages.
 606	 */
 607	if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
 608				(vma->vm_flags & VM_MAYSHARE)))
 609		return 0;
 610
 611	lru_add_drain();
 612	tlb_gather_mmu(&tlb, mm);
 613	madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
 614	tlb_finish_mmu(&tlb);
 615
 616	return 0;
 617}
 618
 619static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 620				unsigned long end, struct mm_walk *walk)
 621
 622{
 623	struct mmu_gather *tlb = walk->private;
 624	struct mm_struct *mm = tlb->mm;
 625	struct vm_area_struct *vma = walk->vma;
 626	spinlock_t *ptl;
 627	pte_t *start_pte, *pte, ptent;
 628	struct folio *folio;
 629	int nr_swap = 0;
 630	unsigned long next;
 631
 632	next = pmd_addr_end(addr, end);
 633	if (pmd_trans_huge(*pmd))
 634		if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
 635			return 0;
 636
 637	tlb_change_page_size(tlb, PAGE_SIZE);
 638	start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 639	if (!start_pte)
 640		return 0;
 641	flush_tlb_batched_pending(mm);
 642	arch_enter_lazy_mmu_mode();
 643	for (; addr != end; pte++, addr += PAGE_SIZE) {
 644		ptent = ptep_get(pte);
 645
 646		if (pte_none(ptent))
 647			continue;
 648		/*
 649		 * If the pte has swp_entry, just clear page table to
 650		 * prevent swap-in which is more expensive rather than
 651		 * (page allocation + zeroing).
 652		 */
 653		if (!pte_present(ptent)) {
 654			swp_entry_t entry;
 655
 656			entry = pte_to_swp_entry(ptent);
 657			if (!non_swap_entry(entry)) {
 658				nr_swap--;
 659				free_swap_and_cache(entry);
 660				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
 661			} else if (is_hwpoison_entry(entry) ||
 662				   is_poisoned_swp_entry(entry)) {
 663				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
 664			}
 665			continue;
 666		}
 667
 668		folio = vm_normal_folio(vma, addr, ptent);
 669		if (!folio || folio_is_zone_device(folio))
 670			continue;
 671
 672		/*
 673		 * If pmd isn't transhuge but the folio is large and
 674		 * is owned by only this process, split it and
 675		 * deactivate all pages.
 676		 */
 677		if (folio_test_large(folio)) {
 678			int err;
 679
 680			if (folio_estimated_sharers(folio) != 1)
 681				break;
 682			if (!folio_trylock(folio))
 683				break;
 684			folio_get(folio);
 685			arch_leave_lazy_mmu_mode();
 686			pte_unmap_unlock(start_pte, ptl);
 687			start_pte = NULL;
 688			err = split_folio(folio);
 689			folio_unlock(folio);
 690			folio_put(folio);
 691			if (err)
 692				break;
 693			start_pte = pte =
 694				pte_offset_map_lock(mm, pmd, addr, &ptl);
 695			if (!start_pte)
 696				break;
 697			arch_enter_lazy_mmu_mode();
 698			pte--;
 699			addr -= PAGE_SIZE;
 700			continue;
 701		}
 702
 703		if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
 704			if (!folio_trylock(folio))
 705				continue;
 706			/*
 707			 * If folio is shared with others, we mustn't clear
 708			 * the folio's dirty flag.
 709			 */
 710			if (folio_mapcount(folio) != 1) {
 711				folio_unlock(folio);
 712				continue;
 713			}
 714
 715			if (folio_test_swapcache(folio) &&
 716			    !folio_free_swap(folio)) {
 717				folio_unlock(folio);
 718				continue;
 719			}
 720
 721			folio_clear_dirty(folio);
 722			folio_unlock(folio);
 723		}
 724
 725		if (pte_young(ptent) || pte_dirty(ptent)) {
 726			/*
 727			 * Some of architecture(ex, PPC) don't update TLB
 728			 * with set_pte_at and tlb_remove_tlb_entry so for
 729			 * the portability, remap the pte with old|clean
 730			 * after pte clearing.
 731			 */
 732			ptent = ptep_get_and_clear_full(mm, addr, pte,
 733							tlb->fullmm);
 734
 735			ptent = pte_mkold(ptent);
 736			ptent = pte_mkclean(ptent);
 737			set_pte_at(mm, addr, pte, ptent);
 738			tlb_remove_tlb_entry(tlb, pte, addr);
 739		}
 740		folio_mark_lazyfree(folio);
 741	}
 742
 743	if (nr_swap)
 744		add_mm_counter(mm, MM_SWAPENTS, nr_swap);
 745	if (start_pte) {
 746		arch_leave_lazy_mmu_mode();
 747		pte_unmap_unlock(start_pte, ptl);
 748	}
 749	cond_resched();
 750
 751	return 0;
 752}
 753
 754static const struct mm_walk_ops madvise_free_walk_ops = {
 755	.pmd_entry		= madvise_free_pte_range,
 756	.walk_lock		= PGWALK_RDLOCK,
 757};
 758
 759static int madvise_free_single_vma(struct vm_area_struct *vma,
 760			unsigned long start_addr, unsigned long end_addr)
 761{
 762	struct mm_struct *mm = vma->vm_mm;
 763	struct mmu_notifier_range range;
 764	struct mmu_gather tlb;
 765
 766	/* MADV_FREE works for only anon vma at the moment */
 767	if (!vma_is_anonymous(vma))
 768		return -EINVAL;
 769
 770	range.start = max(vma->vm_start, start_addr);
 771	if (range.start >= vma->vm_end)
 772		return -EINVAL;
 773	range.end = min(vma->vm_end, end_addr);
 774	if (range.end <= vma->vm_start)
 775		return -EINVAL;
 776	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
 777				range.start, range.end);
 778
 779	lru_add_drain();
 780	tlb_gather_mmu(&tlb, mm);
 781	update_hiwater_rss(mm);
 782
 783	mmu_notifier_invalidate_range_start(&range);
 784	tlb_start_vma(&tlb, vma);
 785	walk_page_range(vma->vm_mm, range.start, range.end,
 786			&madvise_free_walk_ops, &tlb);
 787	tlb_end_vma(&tlb, vma);
 788	mmu_notifier_invalidate_range_end(&range);
 789	tlb_finish_mmu(&tlb);
 790
 
 791	return 0;
 792}
 793
 794/*
 795 * Application no longer needs these pages.  If the pages are dirty,
 796 * it's OK to just throw them away.  The app will be more careful about
 797 * data it wants to keep.  Be sure to free swap resources too.  The
 798 * zap_page_range_single call sets things up for shrink_active_list to actually
 799 * free these pages later if no one else has touched them in the meantime,
 800 * although we could add these pages to a global reuse list for
 801 * shrink_active_list to pick up before reclaiming other pages.
 802 *
 803 * NB: This interface discards data rather than pushes it out to swap,
 804 * as some implementations do.  This has performance implications for
 805 * applications like large transactional databases which want to discard
 806 * pages in anonymous maps after committing to backing store the data
 807 * that was kept in them.  There is no reason to write this data out to
 808 * the swap area if the application is discarding it.
 809 *
 810 * An interface that causes the system to free clean pages and flush
 811 * dirty pages is already available as msync(MS_INVALIDATE).
 812 */
 813static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
 814					unsigned long start, unsigned long end)
 815{
 816	zap_page_range_single(vma, start, end - start, NULL);
 817	return 0;
 818}
 819
 820static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
 821					    unsigned long start,
 822					    unsigned long *end,
 823					    int behavior)
 824{
 825	if (!is_vm_hugetlb_page(vma)) {
 826		unsigned int forbidden = VM_PFNMAP;
 827
 828		if (behavior != MADV_DONTNEED_LOCKED)
 829			forbidden |= VM_LOCKED;
 830
 831		return !(vma->vm_flags & forbidden);
 832	}
 833
 834	if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
 835		return false;
 836	if (start & ~huge_page_mask(hstate_vma(vma)))
 837		return false;
 838
 839	/*
 840	 * Madvise callers expect the length to be rounded up to PAGE_SIZE
 841	 * boundaries, and may be unaware that this VMA uses huge pages.
 842	 * Avoid unexpected data loss by rounding down the number of
 843	 * huge pages freed.
 844	 */
 845	*end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
 846
 847	return true;
 848}
 849
 850static long madvise_dontneed_free(struct vm_area_struct *vma,
 851				  struct vm_area_struct **prev,
 852				  unsigned long start, unsigned long end,
 853				  int behavior)
 854{
 855	struct mm_struct *mm = vma->vm_mm;
 856
 857	*prev = vma;
 858	if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
 859		return -EINVAL;
 860
 861	if (start == end)
 862		return 0;
 863
 864	if (!userfaultfd_remove(vma, start, end)) {
 865		*prev = NULL; /* mmap_lock has been dropped, prev is stale */
 866
 867		mmap_read_lock(mm);
 868		vma = vma_lookup(mm, start);
 869		if (!vma)
 870			return -ENOMEM;
 871		/*
 872		 * Potential end adjustment for hugetlb vma is OK as
 873		 * the check below keeps end within vma.
 874		 */
 875		if (!madvise_dontneed_free_valid_vma(vma, start, &end,
 876						     behavior))
 877			return -EINVAL;
 878		if (end > vma->vm_end) {
 879			/*
 880			 * Don't fail if end > vma->vm_end. If the old
 881			 * vma was split while the mmap_lock was
 882			 * released the effect of the concurrent
 883			 * operation may not cause madvise() to
 884			 * have an undefined result. There may be an
 885			 * adjacent next vma that we'll walk
 886			 * next. userfaultfd_remove() will generate an
 887			 * UFFD_EVENT_REMOVE repetition on the
 888			 * end-vma->vm_end range, but the manager can
 889			 * handle a repetition fine.
 890			 */
 891			end = vma->vm_end;
 892		}
 893		VM_WARN_ON(start >= end);
 894	}
 895
 896	if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
 897		return madvise_dontneed_single_vma(vma, start, end);
 898	else if (behavior == MADV_FREE)
 899		return madvise_free_single_vma(vma, start, end);
 900	else
 901		return -EINVAL;
 902}
 903
 904static long madvise_populate(struct vm_area_struct *vma,
 905			     struct vm_area_struct **prev,
 906			     unsigned long start, unsigned long end,
 907			     int behavior)
 908{
 909	const bool write = behavior == MADV_POPULATE_WRITE;
 910	struct mm_struct *mm = vma->vm_mm;
 911	unsigned long tmp_end;
 912	int locked = 1;
 913	long pages;
 914
 915	*prev = vma;
 
 
 916
 917	while (start < end) {
 918		/*
 919		 * We might have temporarily dropped the lock. For example,
 920		 * our VMA might have been split.
 921		 */
 922		if (!vma || start >= vma->vm_end) {
 923			vma = vma_lookup(mm, start);
 924			if (!vma)
 925				return -ENOMEM;
 926		}
 927
 928		tmp_end = min_t(unsigned long, end, vma->vm_end);
 929		/* Populate (prefault) page tables readable/writable. */
 930		pages = faultin_vma_page_range(vma, start, tmp_end, write,
 931					       &locked);
 932		if (!locked) {
 933			mmap_read_lock(mm);
 934			locked = 1;
 935			*prev = NULL;
 936			vma = NULL;
 937		}
 938		if (pages < 0) {
 939			switch (pages) {
 940			case -EINTR:
 941				return -EINTR;
 942			case -EINVAL: /* Incompatible mappings / permissions. */
 943				return -EINVAL;
 944			case -EHWPOISON:
 945				return -EHWPOISON;
 946			case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
 947				return -EFAULT;
 948			default:
 949				pr_warn_once("%s: unhandled return value: %ld\n",
 950					     __func__, pages);
 951				fallthrough;
 952			case -ENOMEM:
 953				return -ENOMEM;
 954			}
 955		}
 956		start += pages * PAGE_SIZE;
 957	}
 958	return 0;
 959}
 960
 961/*
 962 * Application wants to free up the pages and associated backing store.
 963 * This is effectively punching a hole into the middle of a file.
 
 
 
 964 */
 965static long madvise_remove(struct vm_area_struct *vma,
 966				struct vm_area_struct **prev,
 967				unsigned long start, unsigned long end)
 968{
 969	loff_t offset;
 970	int error;
 971	struct file *f;
 972	struct mm_struct *mm = vma->vm_mm;
 973
 974	*prev = NULL;	/* tell sys_madvise we drop mmap_lock */
 975
 976	if (vma->vm_flags & VM_LOCKED)
 977		return -EINVAL;
 978
 979	f = vma->vm_file;
 980
 981	if (!f || !f->f_mapping || !f->f_mapping->host) {
 982			return -EINVAL;
 983	}
 984
 985	if (!vma_is_shared_maywrite(vma))
 986		return -EACCES;
 987
 988	offset = (loff_t)(start - vma->vm_start)
 989			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 990
 991	/*
 992	 * Filesystem's fallocate may need to take i_rwsem.  We need to
 993	 * explicitly grab a reference because the vma (and hence the
 994	 * vma's reference to the file) can go away as soon as we drop
 995	 * mmap_lock.
 996	 */
 997	get_file(f);
 998	if (userfaultfd_remove(vma, start, end)) {
 999		/* mmap_lock was not released by userfaultfd_remove() */
1000		mmap_read_unlock(mm);
1001	}
1002	error = vfs_fallocate(f,
1003				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
1004				offset, end - start);
1005	fput(f);
1006	mmap_read_lock(mm);
1007	return error;
1008}
1009
1010/*
1011 * Apply an madvise behavior to a region of a vma.  madvise_update_vma
1012 * will handle splitting a vm area into separate areas, each area with its own
1013 * behavior.
1014 */
1015static int madvise_vma_behavior(struct vm_area_struct *vma,
1016				struct vm_area_struct **prev,
1017				unsigned long start, unsigned long end,
1018				unsigned long behavior)
1019{
1020	int error;
1021	struct anon_vma_name *anon_name;
1022	unsigned long new_flags = vma->vm_flags;
1023
1024	switch (behavior) {
1025	case MADV_REMOVE:
1026		return madvise_remove(vma, prev, start, end);
1027	case MADV_WILLNEED:
1028		return madvise_willneed(vma, prev, start, end);
1029	case MADV_COLD:
1030		return madvise_cold(vma, prev, start, end);
1031	case MADV_PAGEOUT:
1032		return madvise_pageout(vma, prev, start, end);
1033	case MADV_FREE:
1034	case MADV_DONTNEED:
1035	case MADV_DONTNEED_LOCKED:
1036		return madvise_dontneed_free(vma, prev, start, end, behavior);
1037	case MADV_POPULATE_READ:
1038	case MADV_POPULATE_WRITE:
1039		return madvise_populate(vma, prev, start, end, behavior);
1040	case MADV_NORMAL:
1041		new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
1042		break;
1043	case MADV_SEQUENTIAL:
1044		new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
1045		break;
1046	case MADV_RANDOM:
1047		new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
1048		break;
1049	case MADV_DONTFORK:
1050		new_flags |= VM_DONTCOPY;
1051		break;
1052	case MADV_DOFORK:
1053		if (vma->vm_flags & VM_IO)
1054			return -EINVAL;
1055		new_flags &= ~VM_DONTCOPY;
1056		break;
1057	case MADV_WIPEONFORK:
1058		/* MADV_WIPEONFORK is only supported on anonymous memory. */
1059		if (vma->vm_file || vma->vm_flags & VM_SHARED)
1060			return -EINVAL;
1061		new_flags |= VM_WIPEONFORK;
1062		break;
1063	case MADV_KEEPONFORK:
1064		new_flags &= ~VM_WIPEONFORK;
1065		break;
1066	case MADV_DONTDUMP:
1067		new_flags |= VM_DONTDUMP;
1068		break;
1069	case MADV_DODUMP:
1070		if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
1071			return -EINVAL;
1072		new_flags &= ~VM_DONTDUMP;
1073		break;
1074	case MADV_MERGEABLE:
1075	case MADV_UNMERGEABLE:
1076		error = ksm_madvise(vma, start, end, behavior, &new_flags);
1077		if (error)
1078			goto out;
1079		break;
1080	case MADV_HUGEPAGE:
1081	case MADV_NOHUGEPAGE:
1082		error = hugepage_madvise(vma, &new_flags, behavior);
1083		if (error)
1084			goto out;
1085		break;
1086	case MADV_COLLAPSE:
1087		return madvise_collapse(vma, prev, start, end);
1088	}
1089
1090	anon_name = anon_vma_name(vma);
1091	anon_vma_name_get(anon_name);
1092	error = madvise_update_vma(vma, prev, start, end, new_flags,
1093				   anon_name);
1094	anon_vma_name_put(anon_name);
1095
1096out:
1097	/*
1098	 * madvise() returns EAGAIN if kernel resources, such as
1099	 * slab, are temporarily unavailable.
1100	 */
1101	if (error == -ENOMEM)
1102		error = -EAGAIN;
1103	return error;
1104}
1105
1106#ifdef CONFIG_MEMORY_FAILURE
1107/*
1108 * Error injection support for memory error handling.
1109 */
1110static int madvise_inject_error(int behavior,
1111		unsigned long start, unsigned long end)
1112{
1113	unsigned long size;
1114
1115	if (!capable(CAP_SYS_ADMIN))
1116		return -EPERM;
1117
1118
1119	for (; start < end; start += size) {
1120		unsigned long pfn;
1121		struct page *page;
1122		int ret;
1123
1124		ret = get_user_pages_fast(start, 1, 0, &page);
1125		if (ret != 1)
1126			return ret;
1127		pfn = page_to_pfn(page);
1128
1129		/*
1130		 * When soft offlining hugepages, after migrating the page
1131		 * we dissolve it, therefore in the second loop "page" will
1132		 * no longer be a compound page.
1133		 */
1134		size = page_size(compound_head(page));
1135
1136		if (behavior == MADV_SOFT_OFFLINE) {
1137			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1138				 pfn, start);
1139			ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
1140		} else {
1141			pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1142				 pfn, start);
1143			ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
1144			if (ret == -EOPNOTSUPP)
1145				ret = 0;
1146		}
1147
1148		if (ret)
1149			return ret;
 
 
 
 
 
 
 
 
 
1150	}
1151
1152	return 0;
1153}
1154#endif
1155
1156static bool
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1157madvise_behavior_valid(int behavior)
1158{
1159	switch (behavior) {
1160	case MADV_DOFORK:
1161	case MADV_DONTFORK:
1162	case MADV_NORMAL:
1163	case MADV_SEQUENTIAL:
1164	case MADV_RANDOM:
1165	case MADV_REMOVE:
1166	case MADV_WILLNEED:
1167	case MADV_DONTNEED:
1168	case MADV_DONTNEED_LOCKED:
1169	case MADV_FREE:
1170	case MADV_COLD:
1171	case MADV_PAGEOUT:
1172	case MADV_POPULATE_READ:
1173	case MADV_POPULATE_WRITE:
1174#ifdef CONFIG_KSM
1175	case MADV_MERGEABLE:
1176	case MADV_UNMERGEABLE:
1177#endif
1178#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1179	case MADV_HUGEPAGE:
1180	case MADV_NOHUGEPAGE:
1181	case MADV_COLLAPSE:
1182#endif
1183	case MADV_DONTDUMP:
1184	case MADV_DODUMP:
1185	case MADV_WIPEONFORK:
1186	case MADV_KEEPONFORK:
1187#ifdef CONFIG_MEMORY_FAILURE
1188	case MADV_SOFT_OFFLINE:
1189	case MADV_HWPOISON:
1190#endif
1191		return true;
1192
1193	default:
1194		return false;
1195	}
1196}
1197
1198static bool process_madvise_behavior_valid(int behavior)
1199{
1200	switch (behavior) {
1201	case MADV_COLD:
1202	case MADV_PAGEOUT:
1203	case MADV_WILLNEED:
1204	case MADV_COLLAPSE:
1205		return true;
1206	default:
1207		return false;
1208	}
1209}
1210
1211/*
1212 * Walk the vmas in range [start,end), and call the visit function on each one.
1213 * The visit function will get start and end parameters that cover the overlap
1214 * between the current vma and the original range.  Any unmapped regions in the
1215 * original range will result in this function returning -ENOMEM while still
1216 * calling the visit function on all of the existing vmas in the range.
1217 * Must be called with the mmap_lock held for reading or writing.
1218 */
1219static
1220int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
1221		      unsigned long end, unsigned long arg,
1222		      int (*visit)(struct vm_area_struct *vma,
1223				   struct vm_area_struct **prev, unsigned long start,
1224				   unsigned long end, unsigned long arg))
1225{
1226	struct vm_area_struct *vma;
1227	struct vm_area_struct *prev;
1228	unsigned long tmp;
1229	int unmapped_error = 0;
1230
1231	/*
1232	 * If the interval [start,end) covers some unmapped address
1233	 * ranges, just ignore them, but return -ENOMEM at the end.
1234	 * - different from the way of handling in mlock etc.
1235	 */
1236	vma = find_vma_prev(mm, start, &prev);
1237	if (vma && start > vma->vm_start)
1238		prev = vma;
1239
1240	for (;;) {
1241		int error;
1242
1243		/* Still start < end. */
1244		if (!vma)
1245			return -ENOMEM;
1246
1247		/* Here start < (end|vma->vm_end). */
1248		if (start < vma->vm_start) {
1249			unmapped_error = -ENOMEM;
1250			start = vma->vm_start;
1251			if (start >= end)
1252				break;
1253		}
1254
1255		/* Here vma->vm_start <= start < (end|vma->vm_end) */
1256		tmp = vma->vm_end;
1257		if (end < tmp)
1258			tmp = end;
1259
1260		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1261		error = visit(vma, &prev, start, tmp, arg);
1262		if (error)
1263			return error;
1264		start = tmp;
1265		if (prev && start < prev->vm_end)
1266			start = prev->vm_end;
1267		if (start >= end)
1268			break;
1269		if (prev)
1270			vma = find_vma(mm, prev->vm_end);
1271		else	/* madvise_remove dropped mmap_lock */
1272			vma = find_vma(mm, start);
1273	}
1274
1275	return unmapped_error;
1276}
1277
1278#ifdef CONFIG_ANON_VMA_NAME
1279static int madvise_vma_anon_name(struct vm_area_struct *vma,
1280				 struct vm_area_struct **prev,
1281				 unsigned long start, unsigned long end,
1282				 unsigned long anon_name)
1283{
1284	int error;
1285
1286	/* Only anonymous mappings can be named */
1287	if (vma->vm_file && !vma_is_anon_shmem(vma))
1288		return -EBADF;
1289
1290	error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
1291				   (struct anon_vma_name *)anon_name);
1292
1293	/*
1294	 * madvise() returns EAGAIN if kernel resources, such as
1295	 * slab, are temporarily unavailable.
1296	 */
1297	if (error == -ENOMEM)
1298		error = -EAGAIN;
1299	return error;
1300}
1301
1302int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
1303			  unsigned long len_in, struct anon_vma_name *anon_name)
1304{
1305	unsigned long end;
1306	unsigned long len;
1307
1308	if (start & ~PAGE_MASK)
1309		return -EINVAL;
1310	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1311
1312	/* Check to see whether len was rounded up from small -ve to zero */
1313	if (len_in && !len)
1314		return -EINVAL;
1315
1316	end = start + len;
1317	if (end < start)
1318		return -EINVAL;
1319
1320	if (end == start)
1321		return 0;
1322
1323	return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
1324				 madvise_vma_anon_name);
1325}
1326#endif /* CONFIG_ANON_VMA_NAME */
1327/*
1328 * The madvise(2) system call.
1329 *
1330 * Applications can use madvise() to advise the kernel how it should
1331 * handle paging I/O in this VM area.  The idea is to help the kernel
1332 * use appropriate read-ahead and caching techniques.  The information
1333 * provided is advisory only, and can be safely disregarded by the
1334 * kernel without affecting the correct operation of the application.
1335 *
1336 * behavior values:
1337 *  MADV_NORMAL - the default behavior is to read clusters.  This
1338 *		results in some read-ahead and read-behind.
1339 *  MADV_RANDOM - the system should read the minimum amount of data
1340 *		on any access, since it is unlikely that the appli-
1341 *		cation will need more than what it asks for.
1342 *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
1343 *		once, so they can be aggressively read ahead, and
1344 *		can be freed soon after they are accessed.
1345 *  MADV_WILLNEED - the application is notifying the system to read
1346 *		some pages ahead.
1347 *  MADV_DONTNEED - the application is finished with the given range,
1348 *		so the kernel can free resources associated with it.
1349 *  MADV_FREE - the application marks pages in the given range as lazy free,
1350 *		where actual purges are postponed until memory pressure happens.
1351 *  MADV_REMOVE - the application wants to free up the given range of
1352 *		pages and associated backing store.
1353 *  MADV_DONTFORK - omit this area from child's address space when forking:
1354 *		typically, to avoid COWing pages pinned by get_user_pages().
1355 *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1356 *  MADV_WIPEONFORK - present the child process with zero-filled memory in this
1357 *              range after a fork.
1358 *  MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1359 *  MADV_HWPOISON - trigger memory error handler as if the given memory range
1360 *		were corrupted by unrecoverable hardware memory failure.
1361 *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1362 *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1363 *		this area with pages of identical content from other such areas.
1364 *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1365 *  MADV_HUGEPAGE - the application wants to back the given range by transparent
1366 *		huge pages in the future. Existing pages might be coalesced and
1367 *		new pages might be allocated as THP.
1368 *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1369 *		transparent huge pages so the existing pages will not be
1370 *		coalesced into THP and new pages will not be allocated as THP.
1371 *  MADV_COLLAPSE - synchronously coalesce pages into new THP.
1372 *  MADV_DONTDUMP - the application wants to prevent pages in the given range
1373 *		from being included in its core dump.
1374 *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1375 *  MADV_COLD - the application is not expected to use this memory soon,
1376 *		deactivate pages in this range so that they can be reclaimed
1377 *		easily if memory pressure happens.
1378 *  MADV_PAGEOUT - the application is not expected to use this memory soon,
1379 *		page out the pages in this range immediately.
1380 *  MADV_POPULATE_READ - populate (prefault) page tables readable by
1381 *		triggering read faults if required
1382 *  MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1383 *		triggering write faults if required
1384 *
1385 * return values:
1386 *  zero    - success
1387 *  -EINVAL - start + len < 0, start is not page-aligned,
1388 *		"behavior" is not a valid value, or application
1389 *		is attempting to release locked or shared pages,
1390 *		or the specified address range includes file, Huge TLB,
1391 *		MAP_SHARED or VMPFNMAP range.
1392 *  -ENOMEM - addresses in the specified range are not currently
1393 *		mapped, or are outside the AS of the process.
1394 *  -EIO    - an I/O error occurred while paging in data.
1395 *  -EBADF  - map exists, but area maps something that isn't a file.
1396 *  -EAGAIN - a kernel resource was temporarily unavailable.
1397 */
1398int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1399{
1400	unsigned long end;
1401	int error;
 
 
1402	int write;
1403	size_t len;
1404	struct blk_plug plug;
1405
 
 
 
 
1406	if (!madvise_behavior_valid(behavior))
1407		return -EINVAL;
1408
1409	if (!PAGE_ALIGNED(start))
1410		return -EINVAL;
1411	len = PAGE_ALIGN(len_in);
1412
1413	/* Check to see whether len was rounded up from small -ve to zero */
1414	if (len_in && !len)
1415		return -EINVAL;
1416
1417	end = start + len;
1418	if (end < start)
1419		return -EINVAL;
1420
 
1421	if (end == start)
1422		return 0;
1423
1424#ifdef CONFIG_MEMORY_FAILURE
1425	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1426		return madvise_inject_error(behavior, start, start + len_in);
1427#endif
1428
1429	write = madvise_need_mmap_write(behavior);
1430	if (write) {
1431		if (mmap_write_lock_killable(mm))
1432			return -EINTR;
1433	} else {
1434		mmap_read_lock(mm);
1435	}
1436
1437	start = untagged_addr_remote(mm, start);
1438	end = start + len;
1439
1440	blk_start_plug(&plug);
1441	error = madvise_walk_vmas(mm, start, end, behavior,
1442			madvise_vma_behavior);
1443	blk_finish_plug(&plug);
1444	if (write)
1445		mmap_write_unlock(mm);
1446	else
1447		mmap_read_unlock(mm);
1448
1449	return error;
1450}
1451
1452SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1453{
1454	return do_madvise(current->mm, start, len_in, behavior);
1455}
1456
1457SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1458		size_t, vlen, int, behavior, unsigned int, flags)
1459{
1460	ssize_t ret;
1461	struct iovec iovstack[UIO_FASTIOV];
1462	struct iovec *iov = iovstack;
1463	struct iov_iter iter;
1464	struct task_struct *task;
1465	struct mm_struct *mm;
1466	size_t total_len;
1467	unsigned int f_flags;
1468
1469	if (flags != 0) {
1470		ret = -EINVAL;
1471		goto out;
1472	}
1473
1474	ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1475	if (ret < 0)
1476		goto out;
1477
1478	task = pidfd_get_task(pidfd, &f_flags);
1479	if (IS_ERR(task)) {
1480		ret = PTR_ERR(task);
1481		goto free_iov;
1482	}
1483
1484	if (!process_madvise_behavior_valid(behavior)) {
1485		ret = -EINVAL;
1486		goto release_task;
1487	}
1488
1489	/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1490	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1491	if (IS_ERR_OR_NULL(mm)) {
1492		ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
1493		goto release_task;
1494	}
1495
1496	/*
1497	 * Require CAP_SYS_NICE for influencing process performance. Note that
1498	 * only non-destructive hints are currently supported.
 
1499	 */
1500	if (!capable(CAP_SYS_NICE)) {
1501		ret = -EPERM;
1502		goto release_mm;
1503	}
1504
1505	total_len = iov_iter_count(&iter);
 
 
 
 
 
1506
1507	while (iov_iter_count(&iter)) {
1508		ret = do_madvise(mm, (unsigned long)iter_iov_addr(&iter),
1509					iter_iov_len(&iter), behavior);
1510		if (ret < 0)
1511			break;
1512		iov_iter_advance(&iter, iter_iov_len(&iter));
1513	}
1514
1515	ret = (total_len - iov_iter_count(&iter)) ? : ret;
 
 
 
1516
1517release_mm:
1518	mmput(mm);
1519release_task:
1520	put_task_struct(task);
1521free_iov:
1522	kfree(iov);
 
 
 
 
 
 
 
 
 
1523out:
1524	return ret;
 
 
 
 
 
 
1525}