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1/*
2 * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 */
32
33#include <linux/types.h>
34#include <linux/sched.h>
35#include <linux/sched/mm.h>
36#include <linux/sched/task.h>
37#include <linux/pid.h>
38#include <linux/slab.h>
39#include <linux/export.h>
40#include <linux/vmalloc.h>
41#include <linux/hugetlb.h>
42#include <linux/interval_tree.h>
43#include <linux/hmm.h>
44#include <linux/pagemap.h>
45
46#include <rdma/ib_umem_odp.h>
47
48#include "uverbs.h"
49
50static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
51 const struct mmu_interval_notifier_ops *ops)
52{
53 int ret;
54
55 umem_odp->umem.is_odp = 1;
56 mutex_init(&umem_odp->umem_mutex);
57
58 if (!umem_odp->is_implicit_odp) {
59 size_t page_size = 1UL << umem_odp->page_shift;
60 unsigned long start;
61 unsigned long end;
62 size_t ndmas, npfns;
63
64 start = ALIGN_DOWN(umem_odp->umem.address, page_size);
65 if (check_add_overflow(umem_odp->umem.address,
66 (unsigned long)umem_odp->umem.length,
67 &end))
68 return -EOVERFLOW;
69 end = ALIGN(end, page_size);
70 if (unlikely(end < page_size))
71 return -EOVERFLOW;
72
73 ndmas = (end - start) >> umem_odp->page_shift;
74 if (!ndmas)
75 return -EINVAL;
76
77 npfns = (end - start) >> PAGE_SHIFT;
78 umem_odp->pfn_list = kvcalloc(
79 npfns, sizeof(*umem_odp->pfn_list), GFP_KERNEL);
80 if (!umem_odp->pfn_list)
81 return -ENOMEM;
82
83 umem_odp->dma_list = kvcalloc(
84 ndmas, sizeof(*umem_odp->dma_list), GFP_KERNEL);
85 if (!umem_odp->dma_list) {
86 ret = -ENOMEM;
87 goto out_pfn_list;
88 }
89
90 ret = mmu_interval_notifier_insert(&umem_odp->notifier,
91 umem_odp->umem.owning_mm,
92 start, end - start, ops);
93 if (ret)
94 goto out_dma_list;
95 }
96
97 return 0;
98
99out_dma_list:
100 kvfree(umem_odp->dma_list);
101out_pfn_list:
102 kvfree(umem_odp->pfn_list);
103 return ret;
104}
105
106/**
107 * ib_umem_odp_alloc_implicit - Allocate a parent implicit ODP umem
108 *
109 * Implicit ODP umems do not have a VA range and do not have any page lists.
110 * They exist only to hold the per_mm reference to help the driver create
111 * children umems.
112 *
113 * @device: IB device to create UMEM
114 * @access: ib_reg_mr access flags
115 */
116struct ib_umem_odp *ib_umem_odp_alloc_implicit(struct ib_device *device,
117 int access)
118{
119 struct ib_umem *umem;
120 struct ib_umem_odp *umem_odp;
121 int ret;
122
123 if (access & IB_ACCESS_HUGETLB)
124 return ERR_PTR(-EINVAL);
125
126 umem_odp = kzalloc(sizeof(*umem_odp), GFP_KERNEL);
127 if (!umem_odp)
128 return ERR_PTR(-ENOMEM);
129 umem = &umem_odp->umem;
130 umem->ibdev = device;
131 umem->writable = ib_access_writable(access);
132 umem->owning_mm = current->mm;
133 umem_odp->is_implicit_odp = 1;
134 umem_odp->page_shift = PAGE_SHIFT;
135
136 umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
137 ret = ib_init_umem_odp(umem_odp, NULL);
138 if (ret) {
139 put_pid(umem_odp->tgid);
140 kfree(umem_odp);
141 return ERR_PTR(ret);
142 }
143 return umem_odp;
144}
145EXPORT_SYMBOL(ib_umem_odp_alloc_implicit);
146
147/**
148 * ib_umem_odp_alloc_child - Allocate a child ODP umem under an implicit
149 * parent ODP umem
150 *
151 * @root: The parent umem enclosing the child. This must be allocated using
152 * ib_alloc_implicit_odp_umem()
153 * @addr: The starting userspace VA
154 * @size: The length of the userspace VA
155 * @ops: MMU interval ops, currently only @invalidate
156 */
157struct ib_umem_odp *
158ib_umem_odp_alloc_child(struct ib_umem_odp *root, unsigned long addr,
159 size_t size,
160 const struct mmu_interval_notifier_ops *ops)
161{
162 /*
163 * Caller must ensure that root cannot be freed during the call to
164 * ib_alloc_odp_umem.
165 */
166 struct ib_umem_odp *odp_data;
167 struct ib_umem *umem;
168 int ret;
169
170 if (WARN_ON(!root->is_implicit_odp))
171 return ERR_PTR(-EINVAL);
172
173 odp_data = kzalloc(sizeof(*odp_data), GFP_KERNEL);
174 if (!odp_data)
175 return ERR_PTR(-ENOMEM);
176 umem = &odp_data->umem;
177 umem->ibdev = root->umem.ibdev;
178 umem->length = size;
179 umem->address = addr;
180 umem->writable = root->umem.writable;
181 umem->owning_mm = root->umem.owning_mm;
182 odp_data->page_shift = PAGE_SHIFT;
183 odp_data->notifier.ops = ops;
184
185 /*
186 * A mmget must be held when registering a notifier, the owming_mm only
187 * has a mm_grab at this point.
188 */
189 if (!mmget_not_zero(umem->owning_mm)) {
190 ret = -EFAULT;
191 goto out_free;
192 }
193
194 odp_data->tgid = get_pid(root->tgid);
195 ret = ib_init_umem_odp(odp_data, ops);
196 if (ret)
197 goto out_tgid;
198 mmput(umem->owning_mm);
199 return odp_data;
200
201out_tgid:
202 put_pid(odp_data->tgid);
203 mmput(umem->owning_mm);
204out_free:
205 kfree(odp_data);
206 return ERR_PTR(ret);
207}
208EXPORT_SYMBOL(ib_umem_odp_alloc_child);
209
210/**
211 * ib_umem_odp_get - Create a umem_odp for a userspace va
212 *
213 * @device: IB device struct to get UMEM
214 * @addr: userspace virtual address to start at
215 * @size: length of region to pin
216 * @access: IB_ACCESS_xxx flags for memory being pinned
217 * @ops: MMU interval ops, currently only @invalidate
218 *
219 * The driver should use when the access flags indicate ODP memory. It avoids
220 * pinning, instead, stores the mm for future page fault handling in
221 * conjunction with MMU notifiers.
222 */
223struct ib_umem_odp *ib_umem_odp_get(struct ib_device *device,
224 unsigned long addr, size_t size, int access,
225 const struct mmu_interval_notifier_ops *ops)
226{
227 struct ib_umem_odp *umem_odp;
228 int ret;
229
230 if (WARN_ON_ONCE(!(access & IB_ACCESS_ON_DEMAND)))
231 return ERR_PTR(-EINVAL);
232
233 umem_odp = kzalloc(sizeof(struct ib_umem_odp), GFP_KERNEL);
234 if (!umem_odp)
235 return ERR_PTR(-ENOMEM);
236
237 umem_odp->umem.ibdev = device;
238 umem_odp->umem.length = size;
239 umem_odp->umem.address = addr;
240 umem_odp->umem.writable = ib_access_writable(access);
241 umem_odp->umem.owning_mm = current->mm;
242 umem_odp->notifier.ops = ops;
243
244 umem_odp->page_shift = PAGE_SHIFT;
245#ifdef CONFIG_HUGETLB_PAGE
246 if (access & IB_ACCESS_HUGETLB)
247 umem_odp->page_shift = HPAGE_SHIFT;
248#endif
249
250 umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
251 ret = ib_init_umem_odp(umem_odp, ops);
252 if (ret)
253 goto err_put_pid;
254 return umem_odp;
255
256err_put_pid:
257 put_pid(umem_odp->tgid);
258 kfree(umem_odp);
259 return ERR_PTR(ret);
260}
261EXPORT_SYMBOL(ib_umem_odp_get);
262
263void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
264{
265 /*
266 * Ensure that no more pages are mapped in the umem.
267 *
268 * It is the driver's responsibility to ensure, before calling us,
269 * that the hardware will not attempt to access the MR any more.
270 */
271 if (!umem_odp->is_implicit_odp) {
272 mutex_lock(&umem_odp->umem_mutex);
273 ib_umem_odp_unmap_dma_pages(umem_odp, ib_umem_start(umem_odp),
274 ib_umem_end(umem_odp));
275 mutex_unlock(&umem_odp->umem_mutex);
276 mmu_interval_notifier_remove(&umem_odp->notifier);
277 kvfree(umem_odp->dma_list);
278 kvfree(umem_odp->pfn_list);
279 }
280 put_pid(umem_odp->tgid);
281 kfree(umem_odp);
282}
283EXPORT_SYMBOL(ib_umem_odp_release);
284
285/*
286 * Map for DMA and insert a single page into the on-demand paging page tables.
287 *
288 * @umem: the umem to insert the page to.
289 * @dma_index: index in the umem to add the dma to.
290 * @page: the page struct to map and add.
291 * @access_mask: access permissions needed for this page.
292 *
293 * The function returns -EFAULT if the DMA mapping operation fails.
294 *
295 */
296static int ib_umem_odp_map_dma_single_page(
297 struct ib_umem_odp *umem_odp,
298 unsigned int dma_index,
299 struct page *page,
300 u64 access_mask)
301{
302 struct ib_device *dev = umem_odp->umem.ibdev;
303 dma_addr_t *dma_addr = &umem_odp->dma_list[dma_index];
304
305 if (*dma_addr) {
306 /*
307 * If the page is already dma mapped it means it went through
308 * a non-invalidating trasition, like read-only to writable.
309 * Resync the flags.
310 */
311 *dma_addr = (*dma_addr & ODP_DMA_ADDR_MASK) | access_mask;
312 return 0;
313 }
314
315 *dma_addr = ib_dma_map_page(dev, page, 0, 1 << umem_odp->page_shift,
316 DMA_BIDIRECTIONAL);
317 if (ib_dma_mapping_error(dev, *dma_addr)) {
318 *dma_addr = 0;
319 return -EFAULT;
320 }
321 umem_odp->npages++;
322 *dma_addr |= access_mask;
323 return 0;
324}
325
326/**
327 * ib_umem_odp_map_dma_and_lock - DMA map userspace memory in an ODP MR and lock it.
328 *
329 * Maps the range passed in the argument to DMA addresses.
330 * The DMA addresses of the mapped pages is updated in umem_odp->dma_list.
331 * Upon success the ODP MR will be locked to let caller complete its device
332 * page table update.
333 *
334 * Returns the number of pages mapped in success, negative error code
335 * for failure.
336 * @umem_odp: the umem to map and pin
337 * @user_virt: the address from which we need to map.
338 * @bcnt: the minimal number of bytes to pin and map. The mapping might be
339 * bigger due to alignment, and may also be smaller in case of an error
340 * pinning or mapping a page. The actual pages mapped is returned in
341 * the return value.
342 * @access_mask: bit mask of the requested access permissions for the given
343 * range.
344 * @fault: is faulting required for the given range
345 */
346int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
347 u64 bcnt, u64 access_mask, bool fault)
348 __acquires(&umem_odp->umem_mutex)
349{
350 struct task_struct *owning_process = NULL;
351 struct mm_struct *owning_mm = umem_odp->umem.owning_mm;
352 int pfn_index, dma_index, ret = 0, start_idx;
353 unsigned int page_shift, hmm_order, pfn_start_idx;
354 unsigned long num_pfns, current_seq;
355 struct hmm_range range = {};
356 unsigned long timeout;
357
358 if (access_mask == 0)
359 return -EINVAL;
360
361 if (user_virt < ib_umem_start(umem_odp) ||
362 user_virt + bcnt > ib_umem_end(umem_odp))
363 return -EFAULT;
364
365 page_shift = umem_odp->page_shift;
366
367 /*
368 * owning_process is allowed to be NULL, this means somehow the mm is
369 * existing beyond the lifetime of the originating process.. Presumably
370 * mmget_not_zero will fail in this case.
371 */
372 owning_process = get_pid_task(umem_odp->tgid, PIDTYPE_PID);
373 if (!owning_process || !mmget_not_zero(owning_mm)) {
374 ret = -EINVAL;
375 goto out_put_task;
376 }
377
378 range.notifier = &umem_odp->notifier;
379 range.start = ALIGN_DOWN(user_virt, 1UL << page_shift);
380 range.end = ALIGN(user_virt + bcnt, 1UL << page_shift);
381 pfn_start_idx = (range.start - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
382 num_pfns = (range.end - range.start) >> PAGE_SHIFT;
383 if (fault) {
384 range.default_flags = HMM_PFN_REQ_FAULT;
385
386 if (access_mask & ODP_WRITE_ALLOWED_BIT)
387 range.default_flags |= HMM_PFN_REQ_WRITE;
388 }
389
390 range.hmm_pfns = &(umem_odp->pfn_list[pfn_start_idx]);
391 timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
392
393retry:
394 current_seq = range.notifier_seq =
395 mmu_interval_read_begin(&umem_odp->notifier);
396
397 mmap_read_lock(owning_mm);
398 ret = hmm_range_fault(&range);
399 mmap_read_unlock(owning_mm);
400 if (unlikely(ret)) {
401 if (ret == -EBUSY && !time_after(jiffies, timeout))
402 goto retry;
403 goto out_put_mm;
404 }
405
406 start_idx = (range.start - ib_umem_start(umem_odp)) >> page_shift;
407 dma_index = start_idx;
408
409 mutex_lock(&umem_odp->umem_mutex);
410 if (mmu_interval_read_retry(&umem_odp->notifier, current_seq)) {
411 mutex_unlock(&umem_odp->umem_mutex);
412 goto retry;
413 }
414
415 for (pfn_index = 0; pfn_index < num_pfns;
416 pfn_index += 1 << (page_shift - PAGE_SHIFT), dma_index++) {
417
418 if (fault) {
419 /*
420 * Since we asked for hmm_range_fault() to populate
421 * pages it shouldn't return an error entry on success.
422 */
423 WARN_ON(range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
424 WARN_ON(!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
425 } else {
426 if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID)) {
427 WARN_ON(umem_odp->dma_list[dma_index]);
428 continue;
429 }
430 access_mask = ODP_READ_ALLOWED_BIT;
431 if (range.hmm_pfns[pfn_index] & HMM_PFN_WRITE)
432 access_mask |= ODP_WRITE_ALLOWED_BIT;
433 }
434
435 hmm_order = hmm_pfn_to_map_order(range.hmm_pfns[pfn_index]);
436 /* If a hugepage was detected and ODP wasn't set for, the umem
437 * page_shift will be used, the opposite case is an error.
438 */
439 if (hmm_order + PAGE_SHIFT < page_shift) {
440 ret = -EINVAL;
441 ibdev_dbg(umem_odp->umem.ibdev,
442 "%s: un-expected hmm_order %u, page_shift %u\n",
443 __func__, hmm_order, page_shift);
444 break;
445 }
446
447 ret = ib_umem_odp_map_dma_single_page(
448 umem_odp, dma_index, hmm_pfn_to_page(range.hmm_pfns[pfn_index]),
449 access_mask);
450 if (ret < 0) {
451 ibdev_dbg(umem_odp->umem.ibdev,
452 "ib_umem_odp_map_dma_single_page failed with error %d\n", ret);
453 break;
454 }
455 }
456 /* upon success lock should stay on hold for the callee */
457 if (!ret)
458 ret = dma_index - start_idx;
459 else
460 mutex_unlock(&umem_odp->umem_mutex);
461
462out_put_mm:
463 mmput_async(owning_mm);
464out_put_task:
465 if (owning_process)
466 put_task_struct(owning_process);
467 return ret;
468}
469EXPORT_SYMBOL(ib_umem_odp_map_dma_and_lock);
470
471void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
472 u64 bound)
473{
474 dma_addr_t dma_addr;
475 dma_addr_t dma;
476 int idx;
477 u64 addr;
478 struct ib_device *dev = umem_odp->umem.ibdev;
479
480 lockdep_assert_held(&umem_odp->umem_mutex);
481
482 virt = max_t(u64, virt, ib_umem_start(umem_odp));
483 bound = min_t(u64, bound, ib_umem_end(umem_odp));
484 for (addr = virt; addr < bound; addr += BIT(umem_odp->page_shift)) {
485 idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
486 dma = umem_odp->dma_list[idx];
487
488 /* The access flags guaranteed a valid DMA address in case was NULL */
489 if (dma) {
490 unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
491 struct page *page = hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
492
493 dma_addr = dma & ODP_DMA_ADDR_MASK;
494 ib_dma_unmap_page(dev, dma_addr,
495 BIT(umem_odp->page_shift),
496 DMA_BIDIRECTIONAL);
497 if (dma & ODP_WRITE_ALLOWED_BIT) {
498 struct page *head_page = compound_head(page);
499 /*
500 * set_page_dirty prefers being called with
501 * the page lock. However, MMU notifiers are
502 * called sometimes with and sometimes without
503 * the lock. We rely on the umem_mutex instead
504 * to prevent other mmu notifiers from
505 * continuing and allowing the page mapping to
506 * be removed.
507 */
508 set_page_dirty(head_page);
509 }
510 umem_odp->dma_list[idx] = 0;
511 umem_odp->npages--;
512 }
513 }
514}
515EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);
1/*
2 * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 */
32
33#include <linux/types.h>
34#include <linux/sched.h>
35#include <linux/sched/mm.h>
36#include <linux/sched/task.h>
37#include <linux/pid.h>
38#include <linux/slab.h>
39#include <linux/export.h>
40#include <linux/vmalloc.h>
41#include <linux/hugetlb.h>
42#include <linux/interval_tree_generic.h>
43
44#include <rdma/ib_verbs.h>
45#include <rdma/ib_umem.h>
46#include <rdma/ib_umem_odp.h>
47
48/*
49 * The ib_umem list keeps track of memory regions for which the HW
50 * device request to receive notification when the related memory
51 * mapping is changed.
52 *
53 * ib_umem_lock protects the list.
54 */
55
56static u64 node_start(struct umem_odp_node *n)
57{
58 struct ib_umem_odp *umem_odp =
59 container_of(n, struct ib_umem_odp, interval_tree);
60
61 return ib_umem_start(umem_odp->umem);
62}
63
64/* Note that the representation of the intervals in the interval tree
65 * considers the ending point as contained in the interval, while the
66 * function ib_umem_end returns the first address which is not contained
67 * in the umem.
68 */
69static u64 node_last(struct umem_odp_node *n)
70{
71 struct ib_umem_odp *umem_odp =
72 container_of(n, struct ib_umem_odp, interval_tree);
73
74 return ib_umem_end(umem_odp->umem) - 1;
75}
76
77INTERVAL_TREE_DEFINE(struct umem_odp_node, rb, u64, __subtree_last,
78 node_start, node_last, static, rbt_ib_umem)
79
80static void ib_umem_notifier_start_account(struct ib_umem *item)
81{
82 mutex_lock(&item->odp_data->umem_mutex);
83
84 /* Only update private counters for this umem if it has them.
85 * Otherwise skip it. All page faults will be delayed for this umem. */
86 if (item->odp_data->mn_counters_active) {
87 int notifiers_count = item->odp_data->notifiers_count++;
88
89 if (notifiers_count == 0)
90 /* Initialize the completion object for waiting on
91 * notifiers. Since notifier_count is zero, no one
92 * should be waiting right now. */
93 reinit_completion(&item->odp_data->notifier_completion);
94 }
95 mutex_unlock(&item->odp_data->umem_mutex);
96}
97
98static void ib_umem_notifier_end_account(struct ib_umem *item)
99{
100 mutex_lock(&item->odp_data->umem_mutex);
101
102 /* Only update private counters for this umem if it has them.
103 * Otherwise skip it. All page faults will be delayed for this umem. */
104 if (item->odp_data->mn_counters_active) {
105 /*
106 * This sequence increase will notify the QP page fault that
107 * the page that is going to be mapped in the spte could have
108 * been freed.
109 */
110 ++item->odp_data->notifiers_seq;
111 if (--item->odp_data->notifiers_count == 0)
112 complete_all(&item->odp_data->notifier_completion);
113 }
114 mutex_unlock(&item->odp_data->umem_mutex);
115}
116
117/* Account for a new mmu notifier in an ib_ucontext. */
118static void ib_ucontext_notifier_start_account(struct ib_ucontext *context)
119{
120 atomic_inc(&context->notifier_count);
121}
122
123/* Account for a terminating mmu notifier in an ib_ucontext.
124 *
125 * Must be called with the ib_ucontext->umem_rwsem semaphore unlocked, since
126 * the function takes the semaphore itself. */
127static void ib_ucontext_notifier_end_account(struct ib_ucontext *context)
128{
129 int zero_notifiers = atomic_dec_and_test(&context->notifier_count);
130
131 if (zero_notifiers &&
132 !list_empty(&context->no_private_counters)) {
133 /* No currently running mmu notifiers. Now is the chance to
134 * add private accounting to all previously added umems. */
135 struct ib_umem_odp *odp_data, *next;
136
137 /* Prevent concurrent mmu notifiers from working on the
138 * no_private_counters list. */
139 down_write(&context->umem_rwsem);
140
141 /* Read the notifier_count again, with the umem_rwsem
142 * semaphore taken for write. */
143 if (!atomic_read(&context->notifier_count)) {
144 list_for_each_entry_safe(odp_data, next,
145 &context->no_private_counters,
146 no_private_counters) {
147 mutex_lock(&odp_data->umem_mutex);
148 odp_data->mn_counters_active = true;
149 list_del(&odp_data->no_private_counters);
150 complete_all(&odp_data->notifier_completion);
151 mutex_unlock(&odp_data->umem_mutex);
152 }
153 }
154
155 up_write(&context->umem_rwsem);
156 }
157}
158
159static int ib_umem_notifier_release_trampoline(struct ib_umem *item, u64 start,
160 u64 end, void *cookie) {
161 /*
162 * Increase the number of notifiers running, to
163 * prevent any further fault handling on this MR.
164 */
165 ib_umem_notifier_start_account(item);
166 item->odp_data->dying = 1;
167 /* Make sure that the fact the umem is dying is out before we release
168 * all pending page faults. */
169 smp_wmb();
170 complete_all(&item->odp_data->notifier_completion);
171 item->context->invalidate_range(item, ib_umem_start(item),
172 ib_umem_end(item));
173 return 0;
174}
175
176static void ib_umem_notifier_release(struct mmu_notifier *mn,
177 struct mm_struct *mm)
178{
179 struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
180
181 if (!context->invalidate_range)
182 return;
183
184 ib_ucontext_notifier_start_account(context);
185 down_read(&context->umem_rwsem);
186 rbt_ib_umem_for_each_in_range(&context->umem_tree, 0,
187 ULLONG_MAX,
188 ib_umem_notifier_release_trampoline,
189 NULL);
190 up_read(&context->umem_rwsem);
191}
192
193static int invalidate_page_trampoline(struct ib_umem *item, u64 start,
194 u64 end, void *cookie)
195{
196 ib_umem_notifier_start_account(item);
197 item->context->invalidate_range(item, start, start + PAGE_SIZE);
198 ib_umem_notifier_end_account(item);
199 return 0;
200}
201
202static int invalidate_range_start_trampoline(struct ib_umem *item, u64 start,
203 u64 end, void *cookie)
204{
205 ib_umem_notifier_start_account(item);
206 item->context->invalidate_range(item, start, end);
207 return 0;
208}
209
210static void ib_umem_notifier_invalidate_range_start(struct mmu_notifier *mn,
211 struct mm_struct *mm,
212 unsigned long start,
213 unsigned long end)
214{
215 struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
216
217 if (!context->invalidate_range)
218 return;
219
220 ib_ucontext_notifier_start_account(context);
221 down_read(&context->umem_rwsem);
222 rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
223 end,
224 invalidate_range_start_trampoline, NULL);
225 up_read(&context->umem_rwsem);
226}
227
228static int invalidate_range_end_trampoline(struct ib_umem *item, u64 start,
229 u64 end, void *cookie)
230{
231 ib_umem_notifier_end_account(item);
232 return 0;
233}
234
235static void ib_umem_notifier_invalidate_range_end(struct mmu_notifier *mn,
236 struct mm_struct *mm,
237 unsigned long start,
238 unsigned long end)
239{
240 struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
241
242 if (!context->invalidate_range)
243 return;
244
245 down_read(&context->umem_rwsem);
246 rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
247 end,
248 invalidate_range_end_trampoline, NULL);
249 up_read(&context->umem_rwsem);
250 ib_ucontext_notifier_end_account(context);
251}
252
253static const struct mmu_notifier_ops ib_umem_notifiers = {
254 .release = ib_umem_notifier_release,
255 .invalidate_range_start = ib_umem_notifier_invalidate_range_start,
256 .invalidate_range_end = ib_umem_notifier_invalidate_range_end,
257};
258
259struct ib_umem *ib_alloc_odp_umem(struct ib_ucontext *context,
260 unsigned long addr,
261 size_t size)
262{
263 struct ib_umem *umem;
264 struct ib_umem_odp *odp_data;
265 int pages = size >> PAGE_SHIFT;
266 int ret;
267
268 umem = kzalloc(sizeof(*umem), GFP_KERNEL);
269 if (!umem)
270 return ERR_PTR(-ENOMEM);
271
272 umem->context = context;
273 umem->length = size;
274 umem->address = addr;
275 umem->page_shift = PAGE_SHIFT;
276 umem->writable = 1;
277
278 odp_data = kzalloc(sizeof(*odp_data), GFP_KERNEL);
279 if (!odp_data) {
280 ret = -ENOMEM;
281 goto out_umem;
282 }
283 odp_data->umem = umem;
284
285 mutex_init(&odp_data->umem_mutex);
286 init_completion(&odp_data->notifier_completion);
287
288 odp_data->page_list = vzalloc(pages * sizeof(*odp_data->page_list));
289 if (!odp_data->page_list) {
290 ret = -ENOMEM;
291 goto out_odp_data;
292 }
293
294 odp_data->dma_list = vzalloc(pages * sizeof(*odp_data->dma_list));
295 if (!odp_data->dma_list) {
296 ret = -ENOMEM;
297 goto out_page_list;
298 }
299
300 down_write(&context->umem_rwsem);
301 context->odp_mrs_count++;
302 rbt_ib_umem_insert(&odp_data->interval_tree, &context->umem_tree);
303 if (likely(!atomic_read(&context->notifier_count)))
304 odp_data->mn_counters_active = true;
305 else
306 list_add(&odp_data->no_private_counters,
307 &context->no_private_counters);
308 up_write(&context->umem_rwsem);
309
310 umem->odp_data = odp_data;
311
312 return umem;
313
314out_page_list:
315 vfree(odp_data->page_list);
316out_odp_data:
317 kfree(odp_data);
318out_umem:
319 kfree(umem);
320 return ERR_PTR(ret);
321}
322EXPORT_SYMBOL(ib_alloc_odp_umem);
323
324int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem,
325 int access)
326{
327 int ret_val;
328 struct pid *our_pid;
329 struct mm_struct *mm = get_task_mm(current);
330
331 if (!mm)
332 return -EINVAL;
333
334 if (access & IB_ACCESS_HUGETLB) {
335 struct vm_area_struct *vma;
336 struct hstate *h;
337
338 down_read(&mm->mmap_sem);
339 vma = find_vma(mm, ib_umem_start(umem));
340 if (!vma || !is_vm_hugetlb_page(vma)) {
341 up_read(&mm->mmap_sem);
342 return -EINVAL;
343 }
344 h = hstate_vma(vma);
345 umem->page_shift = huge_page_shift(h);
346 up_read(&mm->mmap_sem);
347 umem->hugetlb = 1;
348 } else {
349 umem->hugetlb = 0;
350 }
351
352 /* Prevent creating ODP MRs in child processes */
353 rcu_read_lock();
354 our_pid = get_task_pid(current->group_leader, PIDTYPE_PID);
355 rcu_read_unlock();
356 put_pid(our_pid);
357 if (context->tgid != our_pid) {
358 ret_val = -EINVAL;
359 goto out_mm;
360 }
361
362 umem->odp_data = kzalloc(sizeof(*umem->odp_data), GFP_KERNEL);
363 if (!umem->odp_data) {
364 ret_val = -ENOMEM;
365 goto out_mm;
366 }
367 umem->odp_data->umem = umem;
368
369 mutex_init(&umem->odp_data->umem_mutex);
370
371 init_completion(&umem->odp_data->notifier_completion);
372
373 if (ib_umem_num_pages(umem)) {
374 umem->odp_data->page_list = vzalloc(ib_umem_num_pages(umem) *
375 sizeof(*umem->odp_data->page_list));
376 if (!umem->odp_data->page_list) {
377 ret_val = -ENOMEM;
378 goto out_odp_data;
379 }
380
381 umem->odp_data->dma_list = vzalloc(ib_umem_num_pages(umem) *
382 sizeof(*umem->odp_data->dma_list));
383 if (!umem->odp_data->dma_list) {
384 ret_val = -ENOMEM;
385 goto out_page_list;
386 }
387 }
388
389 /*
390 * When using MMU notifiers, we will get a
391 * notification before the "current" task (and MM) is
392 * destroyed. We use the umem_rwsem semaphore to synchronize.
393 */
394 down_write(&context->umem_rwsem);
395 context->odp_mrs_count++;
396 if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
397 rbt_ib_umem_insert(&umem->odp_data->interval_tree,
398 &context->umem_tree);
399 if (likely(!atomic_read(&context->notifier_count)) ||
400 context->odp_mrs_count == 1)
401 umem->odp_data->mn_counters_active = true;
402 else
403 list_add(&umem->odp_data->no_private_counters,
404 &context->no_private_counters);
405 downgrade_write(&context->umem_rwsem);
406
407 if (context->odp_mrs_count == 1) {
408 /*
409 * Note that at this point, no MMU notifier is running
410 * for this context!
411 */
412 atomic_set(&context->notifier_count, 0);
413 INIT_HLIST_NODE(&context->mn.hlist);
414 context->mn.ops = &ib_umem_notifiers;
415 /*
416 * Lock-dep detects a false positive for mmap_sem vs.
417 * umem_rwsem, due to not grasping downgrade_write correctly.
418 */
419 lockdep_off();
420 ret_val = mmu_notifier_register(&context->mn, mm);
421 lockdep_on();
422 if (ret_val) {
423 pr_err("Failed to register mmu_notifier %d\n", ret_val);
424 ret_val = -EBUSY;
425 goto out_mutex;
426 }
427 }
428
429 up_read(&context->umem_rwsem);
430
431 /*
432 * Note that doing an mmput can cause a notifier for the relevant mm.
433 * If the notifier is called while we hold the umem_rwsem, this will
434 * cause a deadlock. Therefore, we release the reference only after we
435 * released the semaphore.
436 */
437 mmput(mm);
438 return 0;
439
440out_mutex:
441 up_read(&context->umem_rwsem);
442 vfree(umem->odp_data->dma_list);
443out_page_list:
444 vfree(umem->odp_data->page_list);
445out_odp_data:
446 kfree(umem->odp_data);
447out_mm:
448 mmput(mm);
449 return ret_val;
450}
451
452void ib_umem_odp_release(struct ib_umem *umem)
453{
454 struct ib_ucontext *context = umem->context;
455
456 /*
457 * Ensure that no more pages are mapped in the umem.
458 *
459 * It is the driver's responsibility to ensure, before calling us,
460 * that the hardware will not attempt to access the MR any more.
461 */
462 ib_umem_odp_unmap_dma_pages(umem, ib_umem_start(umem),
463 ib_umem_end(umem));
464
465 down_write(&context->umem_rwsem);
466 if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
467 rbt_ib_umem_remove(&umem->odp_data->interval_tree,
468 &context->umem_tree);
469 context->odp_mrs_count--;
470 if (!umem->odp_data->mn_counters_active) {
471 list_del(&umem->odp_data->no_private_counters);
472 complete_all(&umem->odp_data->notifier_completion);
473 }
474
475 /*
476 * Downgrade the lock to a read lock. This ensures that the notifiers
477 * (who lock the mutex for reading) will be able to finish, and we
478 * will be able to enventually obtain the mmu notifiers SRCU. Note
479 * that since we are doing it atomically, no other user could register
480 * and unregister while we do the check.
481 */
482 downgrade_write(&context->umem_rwsem);
483 if (!context->odp_mrs_count) {
484 struct task_struct *owning_process = NULL;
485 struct mm_struct *owning_mm = NULL;
486
487 owning_process = get_pid_task(context->tgid,
488 PIDTYPE_PID);
489 if (owning_process == NULL)
490 /*
491 * The process is already dead, notifier were removed
492 * already.
493 */
494 goto out;
495
496 owning_mm = get_task_mm(owning_process);
497 if (owning_mm == NULL)
498 /*
499 * The process' mm is already dead, notifier were
500 * removed already.
501 */
502 goto out_put_task;
503 mmu_notifier_unregister(&context->mn, owning_mm);
504
505 mmput(owning_mm);
506
507out_put_task:
508 put_task_struct(owning_process);
509 }
510out:
511 up_read(&context->umem_rwsem);
512
513 vfree(umem->odp_data->dma_list);
514 vfree(umem->odp_data->page_list);
515 kfree(umem->odp_data);
516 kfree(umem);
517}
518
519/*
520 * Map for DMA and insert a single page into the on-demand paging page tables.
521 *
522 * @umem: the umem to insert the page to.
523 * @page_index: index in the umem to add the page to.
524 * @page: the page struct to map and add.
525 * @access_mask: access permissions needed for this page.
526 * @current_seq: sequence number for synchronization with invalidations.
527 * the sequence number is taken from
528 * umem->odp_data->notifiers_seq.
529 *
530 * The function returns -EFAULT if the DMA mapping operation fails. It returns
531 * -EAGAIN if a concurrent invalidation prevents us from updating the page.
532 *
533 * The page is released via put_page even if the operation failed. For
534 * on-demand pinning, the page is released whenever it isn't stored in the
535 * umem.
536 */
537static int ib_umem_odp_map_dma_single_page(
538 struct ib_umem *umem,
539 int page_index,
540 struct page *page,
541 u64 access_mask,
542 unsigned long current_seq)
543{
544 struct ib_device *dev = umem->context->device;
545 dma_addr_t dma_addr;
546 int stored_page = 0;
547 int remove_existing_mapping = 0;
548 int ret = 0;
549
550 /*
551 * Note: we avoid writing if seq is different from the initial seq, to
552 * handle case of a racing notifier. This check also allows us to bail
553 * early if we have a notifier running in parallel with us.
554 */
555 if (ib_umem_mmu_notifier_retry(umem, current_seq)) {
556 ret = -EAGAIN;
557 goto out;
558 }
559 if (!(umem->odp_data->dma_list[page_index])) {
560 dma_addr = ib_dma_map_page(dev,
561 page,
562 0, BIT(umem->page_shift),
563 DMA_BIDIRECTIONAL);
564 if (ib_dma_mapping_error(dev, dma_addr)) {
565 ret = -EFAULT;
566 goto out;
567 }
568 umem->odp_data->dma_list[page_index] = dma_addr | access_mask;
569 umem->odp_data->page_list[page_index] = page;
570 umem->npages++;
571 stored_page = 1;
572 } else if (umem->odp_data->page_list[page_index] == page) {
573 umem->odp_data->dma_list[page_index] |= access_mask;
574 } else {
575 pr_err("error: got different pages in IB device and from get_user_pages. IB device page: %p, gup page: %p\n",
576 umem->odp_data->page_list[page_index], page);
577 /* Better remove the mapping now, to prevent any further
578 * damage. */
579 remove_existing_mapping = 1;
580 }
581
582out:
583 /* On Demand Paging - avoid pinning the page */
584 if (umem->context->invalidate_range || !stored_page)
585 put_page(page);
586
587 if (remove_existing_mapping && umem->context->invalidate_range) {
588 invalidate_page_trampoline(
589 umem,
590 ib_umem_start(umem) + (page_index >> umem->page_shift),
591 ib_umem_start(umem) + ((page_index + 1) >>
592 umem->page_shift),
593 NULL);
594 ret = -EAGAIN;
595 }
596
597 return ret;
598}
599
600/**
601 * ib_umem_odp_map_dma_pages - Pin and DMA map userspace memory in an ODP MR.
602 *
603 * Pins the range of pages passed in the argument, and maps them to
604 * DMA addresses. The DMA addresses of the mapped pages is updated in
605 * umem->odp_data->dma_list.
606 *
607 * Returns the number of pages mapped in success, negative error code
608 * for failure.
609 * An -EAGAIN error code is returned when a concurrent mmu notifier prevents
610 * the function from completing its task.
611 * An -ENOENT error code indicates that userspace process is being terminated
612 * and mm was already destroyed.
613 * @umem: the umem to map and pin
614 * @user_virt: the address from which we need to map.
615 * @bcnt: the minimal number of bytes to pin and map. The mapping might be
616 * bigger due to alignment, and may also be smaller in case of an error
617 * pinning or mapping a page. The actual pages mapped is returned in
618 * the return value.
619 * @access_mask: bit mask of the requested access permissions for the given
620 * range.
621 * @current_seq: the MMU notifiers sequance value for synchronization with
622 * invalidations. the sequance number is read from
623 * umem->odp_data->notifiers_seq before calling this function
624 */
625int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
626 u64 access_mask, unsigned long current_seq)
627{
628 struct task_struct *owning_process = NULL;
629 struct mm_struct *owning_mm = NULL;
630 struct page **local_page_list = NULL;
631 u64 page_mask, off;
632 int j, k, ret = 0, start_idx, npages = 0, page_shift;
633 unsigned int flags = 0;
634 phys_addr_t p = 0;
635
636 if (access_mask == 0)
637 return -EINVAL;
638
639 if (user_virt < ib_umem_start(umem) ||
640 user_virt + bcnt > ib_umem_end(umem))
641 return -EFAULT;
642
643 local_page_list = (struct page **)__get_free_page(GFP_KERNEL);
644 if (!local_page_list)
645 return -ENOMEM;
646
647 page_shift = umem->page_shift;
648 page_mask = ~(BIT(page_shift) - 1);
649 off = user_virt & (~page_mask);
650 user_virt = user_virt & page_mask;
651 bcnt += off; /* Charge for the first page offset as well. */
652
653 owning_process = get_pid_task(umem->context->tgid, PIDTYPE_PID);
654 if (owning_process == NULL) {
655 ret = -EINVAL;
656 goto out_no_task;
657 }
658
659 owning_mm = get_task_mm(owning_process);
660 if (owning_mm == NULL) {
661 ret = -ENOENT;
662 goto out_put_task;
663 }
664
665 if (access_mask & ODP_WRITE_ALLOWED_BIT)
666 flags |= FOLL_WRITE;
667
668 start_idx = (user_virt - ib_umem_start(umem)) >> page_shift;
669 k = start_idx;
670
671 while (bcnt > 0) {
672 const size_t gup_num_pages = min_t(size_t,
673 (bcnt + BIT(page_shift) - 1) >> page_shift,
674 PAGE_SIZE / sizeof(struct page *));
675
676 down_read(&owning_mm->mmap_sem);
677 /*
678 * Note: this might result in redundent page getting. We can
679 * avoid this by checking dma_list to be 0 before calling
680 * get_user_pages. However, this make the code much more
681 * complex (and doesn't gain us much performance in most use
682 * cases).
683 */
684 npages = get_user_pages_remote(owning_process, owning_mm,
685 user_virt, gup_num_pages,
686 flags, local_page_list, NULL, NULL);
687 up_read(&owning_mm->mmap_sem);
688
689 if (npages < 0)
690 break;
691
692 bcnt -= min_t(size_t, npages << PAGE_SHIFT, bcnt);
693 mutex_lock(&umem->odp_data->umem_mutex);
694 for (j = 0; j < npages; j++, user_virt += PAGE_SIZE) {
695 if (user_virt & ~page_mask) {
696 p += PAGE_SIZE;
697 if (page_to_phys(local_page_list[j]) != p) {
698 ret = -EFAULT;
699 break;
700 }
701 put_page(local_page_list[j]);
702 continue;
703 }
704
705 ret = ib_umem_odp_map_dma_single_page(
706 umem, k, local_page_list[j],
707 access_mask, current_seq);
708 if (ret < 0)
709 break;
710
711 p = page_to_phys(local_page_list[j]);
712 k++;
713 }
714 mutex_unlock(&umem->odp_data->umem_mutex);
715
716 if (ret < 0) {
717 /* Release left over pages when handling errors. */
718 for (++j; j < npages; ++j)
719 put_page(local_page_list[j]);
720 break;
721 }
722 }
723
724 if (ret >= 0) {
725 if (npages < 0 && k == start_idx)
726 ret = npages;
727 else
728 ret = k - start_idx;
729 }
730
731 mmput(owning_mm);
732out_put_task:
733 put_task_struct(owning_process);
734out_no_task:
735 free_page((unsigned long)local_page_list);
736 return ret;
737}
738EXPORT_SYMBOL(ib_umem_odp_map_dma_pages);
739
740void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 virt,
741 u64 bound)
742{
743 int idx;
744 u64 addr;
745 struct ib_device *dev = umem->context->device;
746
747 virt = max_t(u64, virt, ib_umem_start(umem));
748 bound = min_t(u64, bound, ib_umem_end(umem));
749 /* Note that during the run of this function, the
750 * notifiers_count of the MR is > 0, preventing any racing
751 * faults from completion. We might be racing with other
752 * invalidations, so we must make sure we free each page only
753 * once. */
754 mutex_lock(&umem->odp_data->umem_mutex);
755 for (addr = virt; addr < bound; addr += BIT(umem->page_shift)) {
756 idx = (addr - ib_umem_start(umem)) >> umem->page_shift;
757 if (umem->odp_data->page_list[idx]) {
758 struct page *page = umem->odp_data->page_list[idx];
759 dma_addr_t dma = umem->odp_data->dma_list[idx];
760 dma_addr_t dma_addr = dma & ODP_DMA_ADDR_MASK;
761
762 WARN_ON(!dma_addr);
763
764 ib_dma_unmap_page(dev, dma_addr, PAGE_SIZE,
765 DMA_BIDIRECTIONAL);
766 if (dma & ODP_WRITE_ALLOWED_BIT) {
767 struct page *head_page = compound_head(page);
768 /*
769 * set_page_dirty prefers being called with
770 * the page lock. However, MMU notifiers are
771 * called sometimes with and sometimes without
772 * the lock. We rely on the umem_mutex instead
773 * to prevent other mmu notifiers from
774 * continuing and allowing the page mapping to
775 * be removed.
776 */
777 set_page_dirty(head_page);
778 }
779 /* on demand pinning support */
780 if (!umem->context->invalidate_range)
781 put_page(page);
782 umem->odp_data->page_list[idx] = NULL;
783 umem->odp_data->dma_list[idx] = 0;
784 umem->npages--;
785 }
786 }
787 mutex_unlock(&umem->odp_data->umem_mutex);
788}
789EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);
790
791/* @last is not a part of the interval. See comment for function
792 * node_last.
793 */
794int rbt_ib_umem_for_each_in_range(struct rb_root_cached *root,
795 u64 start, u64 last,
796 umem_call_back cb,
797 void *cookie)
798{
799 int ret_val = 0;
800 struct umem_odp_node *node, *next;
801 struct ib_umem_odp *umem;
802
803 if (unlikely(start == last))
804 return ret_val;
805
806 for (node = rbt_ib_umem_iter_first(root, start, last - 1);
807 node; node = next) {
808 next = rbt_ib_umem_iter_next(node, start, last - 1);
809 umem = container_of(node, struct ib_umem_odp, interval_tree);
810 ret_val = cb(umem->umem, start, last, cookie) || ret_val;
811 }
812
813 return ret_val;
814}
815EXPORT_SYMBOL(rbt_ib_umem_for_each_in_range);
816
817struct ib_umem_odp *rbt_ib_umem_lookup(struct rb_root_cached *root,
818 u64 addr, u64 length)
819{
820 struct umem_odp_node *node;
821
822 node = rbt_ib_umem_iter_first(root, addr, addr + length - 1);
823 if (node)
824 return container_of(node, struct ib_umem_odp, interval_tree);
825 return NULL;
826
827}
828EXPORT_SYMBOL(rbt_ib_umem_lookup);