1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/kernel.h>
3 #include <linux/errno.h>
5 #include <linux/spinlock.h>
8 #include <linux/memremap.h>
9 #include <linux/pagemap.h>
10 #include <linux/rmap.h>
11 #include <linux/swap.h>
12 #include <linux/swapops.h>
13 #include <linux/secretmem.h>
15 #include <linux/sched/signal.h>
16 #include <linux/rwsem.h>
17 #include <linux/hugetlb.h>
18 #include <linux/migrate.h>
19 #include <linux/mm_inline.h>
20 #include <linux/sched/mm.h>
22 #include <asm/mmu_context.h>
23 #include <asm/tlbflush.h>
27 struct follow_page_context
{
28 struct dev_pagemap
*pgmap
;
29 unsigned int page_mask
;
32 static void hpage_pincount_add(struct page
*page
, int refs
)
34 VM_BUG_ON_PAGE(!hpage_pincount_available(page
), page
);
35 VM_BUG_ON_PAGE(page
!= compound_head(page
), page
);
37 atomic_add(refs
, compound_pincount_ptr(page
));
40 static void hpage_pincount_sub(struct page
*page
, int refs
)
42 VM_BUG_ON_PAGE(!hpage_pincount_available(page
), page
);
43 VM_BUG_ON_PAGE(page
!= compound_head(page
), page
);
45 atomic_sub(refs
, compound_pincount_ptr(page
));
48 /* Equivalent to calling put_page() @refs times. */
49 static void put_page_refs(struct page
*page
, int refs
)
51 #ifdef CONFIG_DEBUG_VM
52 if (VM_WARN_ON_ONCE_PAGE(page_ref_count(page
) < refs
, page
))
57 * Calling put_page() for each ref is unnecessarily slow. Only the last
58 * ref needs a put_page().
61 page_ref_sub(page
, refs
- 1);
66 * Return the compound head page with ref appropriately incremented,
67 * or NULL if that failed.
69 static inline struct page
*try_get_compound_head(struct page
*page
, int refs
)
71 struct page
*head
= compound_head(page
);
73 if (WARN_ON_ONCE(page_ref_count(head
) < 0))
75 if (unlikely(!page_cache_add_speculative(head
, refs
)))
79 * At this point we have a stable reference to the head page; but it
80 * could be that between the compound_head() lookup and the refcount
81 * increment, the compound page was split, in which case we'd end up
82 * holding a reference on a page that has nothing to do with the page
83 * we were given anymore.
84 * So now that the head page is stable, recheck that the pages still
87 if (unlikely(compound_head(page
) != head
)) {
88 put_page_refs(head
, refs
);
96 * try_grab_compound_head() - attempt to elevate a page's refcount, by a
97 * flags-dependent amount.
99 * Even though the name includes "compound_head", this function is still
100 * appropriate for callers that have a non-compound @page to get.
102 * @page: pointer to page to be grabbed
103 * @refs: the value to (effectively) add to the page's refcount
104 * @flags: gup flags: these are the FOLL_* flag values.
106 * "grab" names in this file mean, "look at flags to decide whether to use
107 * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.
109 * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the
110 * same time. (That's true throughout the get_user_pages*() and
111 * pin_user_pages*() APIs.) Cases:
113 * FOLL_GET: page's refcount will be incremented by @refs.
115 * FOLL_PIN on compound pages that are > two pages long: page's refcount will
116 * be incremented by @refs, and page[2].hpage_pinned_refcount will be
117 * incremented by @refs * GUP_PIN_COUNTING_BIAS.
119 * FOLL_PIN on normal pages, or compound pages that are two pages long:
120 * page's refcount will be incremented by @refs * GUP_PIN_COUNTING_BIAS.
122 * Return: head page (with refcount appropriately incremented) for success, or
123 * NULL upon failure. If neither FOLL_GET nor FOLL_PIN was set, that's
124 * considered failure, and furthermore, a likely bug in the caller, so a warning
127 __maybe_unused
struct page
*try_grab_compound_head(struct page
*page
,
128 int refs
, unsigned int flags
)
130 if (flags
& FOLL_GET
)
131 return try_get_compound_head(page
, refs
);
132 else if (flags
& FOLL_PIN
) {
134 * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
135 * right zone, so fail and let the caller fall back to the slow
138 if (unlikely((flags
& FOLL_LONGTERM
) &&
139 !is_pinnable_page(page
)))
143 * CAUTION: Don't use compound_head() on the page before this
144 * point, the result won't be stable.
146 page
= try_get_compound_head(page
, refs
);
151 * When pinning a compound page of order > 1 (which is what
152 * hpage_pincount_available() checks for), use an exact count to
153 * track it, via hpage_pincount_add/_sub().
155 * However, be sure to *also* increment the normal page refcount
156 * field at least once, so that the page really is pinned.
157 * That's why the refcount from the earlier
158 * try_get_compound_head() is left intact.
160 if (hpage_pincount_available(page
))
161 hpage_pincount_add(page
, refs
);
163 page_ref_add(page
, refs
* (GUP_PIN_COUNTING_BIAS
- 1));
165 mod_node_page_state(page_pgdat(page
), NR_FOLL_PIN_ACQUIRED
,
175 static void put_compound_head(struct page
*page
, int refs
, unsigned int flags
)
177 if (flags
& FOLL_PIN
) {
178 mod_node_page_state(page_pgdat(page
), NR_FOLL_PIN_RELEASED
,
181 if (hpage_pincount_available(page
))
182 hpage_pincount_sub(page
, refs
);
184 refs
*= GUP_PIN_COUNTING_BIAS
;
187 put_page_refs(page
, refs
);
191 * try_grab_page() - elevate a page's refcount by a flag-dependent amount
193 * This might not do anything at all, depending on the flags argument.
195 * "grab" names in this file mean, "look at flags to decide whether to use
196 * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.
198 * @page: pointer to page to be grabbed
199 * @flags: gup flags: these are the FOLL_* flag values.
201 * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same
202 * time. Cases: please see the try_grab_compound_head() documentation, with
205 * Return: true for success, or if no action was required (if neither FOLL_PIN
206 * nor FOLL_GET was set, nothing is done). False for failure: FOLL_GET or
207 * FOLL_PIN was set, but the page could not be grabbed.
209 bool __must_check
try_grab_page(struct page
*page
, unsigned int flags
)
211 WARN_ON_ONCE((flags
& (FOLL_GET
| FOLL_PIN
)) == (FOLL_GET
| FOLL_PIN
));
213 if (flags
& FOLL_GET
)
214 return try_get_page(page
);
215 else if (flags
& FOLL_PIN
) {
218 page
= compound_head(page
);
220 if (WARN_ON_ONCE(page_ref_count(page
) <= 0))
223 if (hpage_pincount_available(page
))
224 hpage_pincount_add(page
, 1);
226 refs
= GUP_PIN_COUNTING_BIAS
;
229 * Similar to try_grab_compound_head(): even if using the
230 * hpage_pincount_add/_sub() routines, be sure to
231 * *also* increment the normal page refcount field at least
232 * once, so that the page really is pinned.
234 page_ref_add(page
, refs
);
236 mod_node_page_state(page_pgdat(page
), NR_FOLL_PIN_ACQUIRED
, 1);
243 * unpin_user_page() - release a dma-pinned page
244 * @page: pointer to page to be released
246 * Pages that were pinned via pin_user_pages*() must be released via either
247 * unpin_user_page(), or one of the unpin_user_pages*() routines. This is so
248 * that such pages can be separately tracked and uniquely handled. In
249 * particular, interactions with RDMA and filesystems need special handling.
251 void unpin_user_page(struct page
*page
)
253 put_compound_head(compound_head(page
), 1, FOLL_PIN
);
255 EXPORT_SYMBOL(unpin_user_page
);
257 static inline void compound_range_next(unsigned long i
, unsigned long npages
,
258 struct page
**list
, struct page
**head
,
259 unsigned int *ntails
)
261 struct page
*next
, *page
;
268 page
= compound_head(next
);
269 if (PageCompound(page
) && compound_order(page
) >= 1)
270 nr
= min_t(unsigned int,
271 page
+ compound_nr(page
) - next
, npages
- i
);
277 #define for_each_compound_range(__i, __list, __npages, __head, __ntails) \
279 compound_range_next(__i, __npages, __list, &(__head), &(__ntails)); \
280 __i < __npages; __i += __ntails, \
281 compound_range_next(__i, __npages, __list, &(__head), &(__ntails)))
283 static inline void compound_next(unsigned long i
, unsigned long npages
,
284 struct page
**list
, struct page
**head
,
285 unsigned int *ntails
)
293 page
= compound_head(list
[i
]);
294 for (nr
= i
+ 1; nr
< npages
; nr
++) {
295 if (compound_head(list
[nr
]) != page
)
303 #define for_each_compound_head(__i, __list, __npages, __head, __ntails) \
305 compound_next(__i, __npages, __list, &(__head), &(__ntails)); \
306 __i < __npages; __i += __ntails, \
307 compound_next(__i, __npages, __list, &(__head), &(__ntails)))
310 * unpin_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages
311 * @pages: array of pages to be maybe marked dirty, and definitely released.
312 * @npages: number of pages in the @pages array.
313 * @make_dirty: whether to mark the pages dirty
315 * "gup-pinned page" refers to a page that has had one of the get_user_pages()
316 * variants called on that page.
318 * For each page in the @pages array, make that page (or its head page, if a
319 * compound page) dirty, if @make_dirty is true, and if the page was previously
320 * listed as clean. In any case, releases all pages using unpin_user_page(),
321 * possibly via unpin_user_pages(), for the non-dirty case.
323 * Please see the unpin_user_page() documentation for details.
325 * set_page_dirty_lock() is used internally. If instead, set_page_dirty() is
326 * required, then the caller should a) verify that this is really correct,
327 * because _lock() is usually required, and b) hand code it:
328 * set_page_dirty_lock(), unpin_user_page().
331 void unpin_user_pages_dirty_lock(struct page
**pages
, unsigned long npages
,
339 unpin_user_pages(pages
, npages
);
343 for_each_compound_head(index
, pages
, npages
, head
, ntails
) {
345 * Checking PageDirty at this point may race with
346 * clear_page_dirty_for_io(), but that's OK. Two key
349 * 1) This code sees the page as already dirty, so it
350 * skips the call to set_page_dirty(). That could happen
351 * because clear_page_dirty_for_io() called
352 * page_mkclean(), followed by set_page_dirty().
353 * However, now the page is going to get written back,
354 * which meets the original intention of setting it
355 * dirty, so all is well: clear_page_dirty_for_io() goes
356 * on to call TestClearPageDirty(), and write the page
359 * 2) This code sees the page as clean, so it calls
360 * set_page_dirty(). The page stays dirty, despite being
361 * written back, so it gets written back again in the
362 * next writeback cycle. This is harmless.
364 if (!PageDirty(head
))
365 set_page_dirty_lock(head
);
366 put_compound_head(head
, ntails
, FOLL_PIN
);
369 EXPORT_SYMBOL(unpin_user_pages_dirty_lock
);
372 * unpin_user_page_range_dirty_lock() - release and optionally dirty
373 * gup-pinned page range
375 * @page: the starting page of a range maybe marked dirty, and definitely released.
376 * @npages: number of consecutive pages to release.
377 * @make_dirty: whether to mark the pages dirty
379 * "gup-pinned page range" refers to a range of pages that has had one of the
380 * pin_user_pages() variants called on that page.
382 * For the page ranges defined by [page .. page+npages], make that range (or
383 * its head pages, if a compound page) dirty, if @make_dirty is true, and if the
384 * page range was previously listed as clean.
386 * set_page_dirty_lock() is used internally. If instead, set_page_dirty() is
387 * required, then the caller should a) verify that this is really correct,
388 * because _lock() is usually required, and b) hand code it:
389 * set_page_dirty_lock(), unpin_user_page().
392 void unpin_user_page_range_dirty_lock(struct page
*page
, unsigned long npages
,
399 for_each_compound_range(index
, &page
, npages
, head
, ntails
) {
400 if (make_dirty
&& !PageDirty(head
))
401 set_page_dirty_lock(head
);
402 put_compound_head(head
, ntails
, FOLL_PIN
);
405 EXPORT_SYMBOL(unpin_user_page_range_dirty_lock
);
408 * unpin_user_pages() - release an array of gup-pinned pages.
409 * @pages: array of pages to be marked dirty and released.
410 * @npages: number of pages in the @pages array.
412 * For each page in the @pages array, release the page using unpin_user_page().
414 * Please see the unpin_user_page() documentation for details.
416 void unpin_user_pages(struct page
**pages
, unsigned long npages
)
423 * If this WARN_ON() fires, then the system *might* be leaking pages (by
424 * leaving them pinned), but probably not. More likely, gup/pup returned
425 * a hard -ERRNO error to the caller, who erroneously passed it here.
427 if (WARN_ON(IS_ERR_VALUE(npages
)))
430 for_each_compound_head(index
, pages
, npages
, head
, ntails
)
431 put_compound_head(head
, ntails
, FOLL_PIN
);
433 EXPORT_SYMBOL(unpin_user_pages
);
436 * Set the MMF_HAS_PINNED if not set yet; after set it'll be there for the mm's
437 * lifecycle. Avoid setting the bit unless necessary, or it might cause write
438 * cache bouncing on large SMP machines for concurrent pinned gups.
440 static inline void mm_set_has_pinned_flag(unsigned long *mm_flags
)
442 if (!test_bit(MMF_HAS_PINNED
, mm_flags
))
443 set_bit(MMF_HAS_PINNED
, mm_flags
);
447 static struct page
*no_page_table(struct vm_area_struct
*vma
,
451 * When core dumping an enormous anonymous area that nobody
452 * has touched so far, we don't want to allocate unnecessary pages or
453 * page tables. Return error instead of NULL to skip handle_mm_fault,
454 * then get_dump_page() will return NULL to leave a hole in the dump.
455 * But we can only make this optimization where a hole would surely
456 * be zero-filled if handle_mm_fault() actually did handle it.
458 if ((flags
& FOLL_DUMP
) &&
459 (vma_is_anonymous(vma
) || !vma
->vm_ops
->fault
))
460 return ERR_PTR(-EFAULT
);
464 static int follow_pfn_pte(struct vm_area_struct
*vma
, unsigned long address
,
465 pte_t
*pte
, unsigned int flags
)
467 /* No page to get reference */
468 if (flags
& FOLL_GET
)
471 if (flags
& FOLL_TOUCH
) {
474 if (flags
& FOLL_WRITE
)
475 entry
= pte_mkdirty(entry
);
476 entry
= pte_mkyoung(entry
);
478 if (!pte_same(*pte
, entry
)) {
479 set_pte_at(vma
->vm_mm
, address
, pte
, entry
);
480 update_mmu_cache(vma
, address
, pte
);
484 /* Proper page table entry exists, but no corresponding struct page */
489 * FOLL_FORCE can write to even unwritable pte's, but only
490 * after we've gone through a COW cycle and they are dirty.
492 static inline bool can_follow_write_pte(pte_t pte
, unsigned int flags
)
494 return pte_write(pte
) ||
495 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pte_dirty(pte
));
498 static struct page
*follow_page_pte(struct vm_area_struct
*vma
,
499 unsigned long address
, pmd_t
*pmd
, unsigned int flags
,
500 struct dev_pagemap
**pgmap
)
502 struct mm_struct
*mm
= vma
->vm_mm
;
508 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
509 if (WARN_ON_ONCE((flags
& (FOLL_PIN
| FOLL_GET
)) ==
510 (FOLL_PIN
| FOLL_GET
)))
511 return ERR_PTR(-EINVAL
);
513 if (unlikely(pmd_bad(*pmd
)))
514 return no_page_table(vma
, flags
);
516 ptep
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
518 if (!pte_present(pte
)) {
521 * KSM's break_ksm() relies upon recognizing a ksm page
522 * even while it is being migrated, so for that case we
523 * need migration_entry_wait().
525 if (likely(!(flags
& FOLL_MIGRATION
)))
529 entry
= pte_to_swp_entry(pte
);
530 if (!is_migration_entry(entry
))
532 pte_unmap_unlock(ptep
, ptl
);
533 migration_entry_wait(mm
, pmd
, address
);
536 if ((flags
& FOLL_NUMA
) && pte_protnone(pte
))
538 if ((flags
& FOLL_WRITE
) && !can_follow_write_pte(pte
, flags
)) {
539 pte_unmap_unlock(ptep
, ptl
);
543 page
= vm_normal_page(vma
, address
, pte
);
544 if (!page
&& pte_devmap(pte
) && (flags
& (FOLL_GET
| FOLL_PIN
))) {
546 * Only return device mapping pages in the FOLL_GET or FOLL_PIN
547 * case since they are only valid while holding the pgmap
550 *pgmap
= get_dev_pagemap(pte_pfn(pte
), *pgmap
);
552 page
= pte_page(pte
);
555 } else if (unlikely(!page
)) {
556 if (flags
& FOLL_DUMP
) {
557 /* Avoid special (like zero) pages in core dumps */
558 page
= ERR_PTR(-EFAULT
);
562 if (is_zero_pfn(pte_pfn(pte
))) {
563 page
= pte_page(pte
);
565 ret
= follow_pfn_pte(vma
, address
, ptep
, flags
);
571 /* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */
572 if (unlikely(!try_grab_page(page
, flags
))) {
573 page
= ERR_PTR(-ENOMEM
);
577 * We need to make the page accessible if and only if we are going
578 * to access its content (the FOLL_PIN case). Please see
579 * Documentation/core-api/pin_user_pages.rst for details.
581 if (flags
& FOLL_PIN
) {
582 ret
= arch_make_page_accessible(page
);
584 unpin_user_page(page
);
589 if (flags
& FOLL_TOUCH
) {
590 if ((flags
& FOLL_WRITE
) &&
591 !pte_dirty(pte
) && !PageDirty(page
))
592 set_page_dirty(page
);
594 * pte_mkyoung() would be more correct here, but atomic care
595 * is needed to avoid losing the dirty bit: it is easier to use
596 * mark_page_accessed().
598 mark_page_accessed(page
);
600 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
601 /* Do not mlock pte-mapped THP */
602 if (PageTransCompound(page
))
606 * The preliminary mapping check is mainly to avoid the
607 * pointless overhead of lock_page on the ZERO_PAGE
608 * which might bounce very badly if there is contention.
610 * If the page is already locked, we don't need to
611 * handle it now - vmscan will handle it later if and
612 * when it attempts to reclaim the page.
614 if (page
->mapping
&& trylock_page(page
)) {
615 lru_add_drain(); /* push cached pages to LRU */
617 * Because we lock page here, and migration is
618 * blocked by the pte's page reference, and we
619 * know the page is still mapped, we don't even
620 * need to check for file-cache page truncation.
622 mlock_vma_page(page
);
627 pte_unmap_unlock(ptep
, ptl
);
630 pte_unmap_unlock(ptep
, ptl
);
633 return no_page_table(vma
, flags
);
636 static struct page
*follow_pmd_mask(struct vm_area_struct
*vma
,
637 unsigned long address
, pud_t
*pudp
,
639 struct follow_page_context
*ctx
)
644 struct mm_struct
*mm
= vma
->vm_mm
;
646 pmd
= pmd_offset(pudp
, address
);
648 * The READ_ONCE() will stabilize the pmdval in a register or
649 * on the stack so that it will stop changing under the code.
651 pmdval
= READ_ONCE(*pmd
);
652 if (pmd_none(pmdval
))
653 return no_page_table(vma
, flags
);
654 if (pmd_huge(pmdval
) && is_vm_hugetlb_page(vma
)) {
655 page
= follow_huge_pmd(mm
, address
, pmd
, flags
);
658 return no_page_table(vma
, flags
);
660 if (is_hugepd(__hugepd(pmd_val(pmdval
)))) {
661 page
= follow_huge_pd(vma
, address
,
662 __hugepd(pmd_val(pmdval
)), flags
,
666 return no_page_table(vma
, flags
);
669 if (!pmd_present(pmdval
)) {
670 if (likely(!(flags
& FOLL_MIGRATION
)))
671 return no_page_table(vma
, flags
);
672 VM_BUG_ON(thp_migration_supported() &&
673 !is_pmd_migration_entry(pmdval
));
674 if (is_pmd_migration_entry(pmdval
))
675 pmd_migration_entry_wait(mm
, pmd
);
676 pmdval
= READ_ONCE(*pmd
);
678 * MADV_DONTNEED may convert the pmd to null because
679 * mmap_lock is held in read mode
681 if (pmd_none(pmdval
))
682 return no_page_table(vma
, flags
);
685 if (pmd_devmap(pmdval
)) {
686 ptl
= pmd_lock(mm
, pmd
);
687 page
= follow_devmap_pmd(vma
, address
, pmd
, flags
, &ctx
->pgmap
);
692 if (likely(!pmd_trans_huge(pmdval
)))
693 return follow_page_pte(vma
, address
, pmd
, flags
, &ctx
->pgmap
);
695 if ((flags
& FOLL_NUMA
) && pmd_protnone(pmdval
))
696 return no_page_table(vma
, flags
);
699 ptl
= pmd_lock(mm
, pmd
);
700 if (unlikely(pmd_none(*pmd
))) {
702 return no_page_table(vma
, flags
);
704 if (unlikely(!pmd_present(*pmd
))) {
706 if (likely(!(flags
& FOLL_MIGRATION
)))
707 return no_page_table(vma
, flags
);
708 pmd_migration_entry_wait(mm
, pmd
);
711 if (unlikely(!pmd_trans_huge(*pmd
))) {
713 return follow_page_pte(vma
, address
, pmd
, flags
, &ctx
->pgmap
);
715 if (flags
& FOLL_SPLIT_PMD
) {
717 page
= pmd_page(*pmd
);
718 if (is_huge_zero_page(page
)) {
721 split_huge_pmd(vma
, pmd
, address
);
722 if (pmd_trans_unstable(pmd
))
726 split_huge_pmd(vma
, pmd
, address
);
727 ret
= pte_alloc(mm
, pmd
) ? -ENOMEM
: 0;
730 return ret
? ERR_PTR(ret
) :
731 follow_page_pte(vma
, address
, pmd
, flags
, &ctx
->pgmap
);
733 page
= follow_trans_huge_pmd(vma
, address
, pmd
, flags
);
735 ctx
->page_mask
= HPAGE_PMD_NR
- 1;
739 static struct page
*follow_pud_mask(struct vm_area_struct
*vma
,
740 unsigned long address
, p4d_t
*p4dp
,
742 struct follow_page_context
*ctx
)
747 struct mm_struct
*mm
= vma
->vm_mm
;
749 pud
= pud_offset(p4dp
, address
);
751 return no_page_table(vma
, flags
);
752 if (pud_huge(*pud
) && is_vm_hugetlb_page(vma
)) {
753 page
= follow_huge_pud(mm
, address
, pud
, flags
);
756 return no_page_table(vma
, flags
);
758 if (is_hugepd(__hugepd(pud_val(*pud
)))) {
759 page
= follow_huge_pd(vma
, address
,
760 __hugepd(pud_val(*pud
)), flags
,
764 return no_page_table(vma
, flags
);
766 if (pud_devmap(*pud
)) {
767 ptl
= pud_lock(mm
, pud
);
768 page
= follow_devmap_pud(vma
, address
, pud
, flags
, &ctx
->pgmap
);
773 if (unlikely(pud_bad(*pud
)))
774 return no_page_table(vma
, flags
);
776 return follow_pmd_mask(vma
, address
, pud
, flags
, ctx
);
779 static struct page
*follow_p4d_mask(struct vm_area_struct
*vma
,
780 unsigned long address
, pgd_t
*pgdp
,
782 struct follow_page_context
*ctx
)
787 p4d
= p4d_offset(pgdp
, address
);
789 return no_page_table(vma
, flags
);
790 BUILD_BUG_ON(p4d_huge(*p4d
));
791 if (unlikely(p4d_bad(*p4d
)))
792 return no_page_table(vma
, flags
);
794 if (is_hugepd(__hugepd(p4d_val(*p4d
)))) {
795 page
= follow_huge_pd(vma
, address
,
796 __hugepd(p4d_val(*p4d
)), flags
,
800 return no_page_table(vma
, flags
);
802 return follow_pud_mask(vma
, address
, p4d
, flags
, ctx
);
806 * follow_page_mask - look up a page descriptor from a user-virtual address
807 * @vma: vm_area_struct mapping @address
808 * @address: virtual address to look up
809 * @flags: flags modifying lookup behaviour
810 * @ctx: contains dev_pagemap for %ZONE_DEVICE memory pinning and a
811 * pointer to output page_mask
813 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
815 * When getting pages from ZONE_DEVICE memory, the @ctx->pgmap caches
816 * the device's dev_pagemap metadata to avoid repeating expensive lookups.
818 * On output, the @ctx->page_mask is set according to the size of the page.
820 * Return: the mapped (struct page *), %NULL if no mapping exists, or
821 * an error pointer if there is a mapping to something not represented
822 * by a page descriptor (see also vm_normal_page()).
824 static struct page
*follow_page_mask(struct vm_area_struct
*vma
,
825 unsigned long address
, unsigned int flags
,
826 struct follow_page_context
*ctx
)
830 struct mm_struct
*mm
= vma
->vm_mm
;
834 /* make this handle hugepd */
835 page
= follow_huge_addr(mm
, address
, flags
& FOLL_WRITE
);
837 WARN_ON_ONCE(flags
& (FOLL_GET
| FOLL_PIN
));
841 pgd
= pgd_offset(mm
, address
);
843 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
844 return no_page_table(vma
, flags
);
846 if (pgd_huge(*pgd
)) {
847 page
= follow_huge_pgd(mm
, address
, pgd
, flags
);
850 return no_page_table(vma
, flags
);
852 if (is_hugepd(__hugepd(pgd_val(*pgd
)))) {
853 page
= follow_huge_pd(vma
, address
,
854 __hugepd(pgd_val(*pgd
)), flags
,
858 return no_page_table(vma
, flags
);
861 return follow_p4d_mask(vma
, address
, pgd
, flags
, ctx
);
864 struct page
*follow_page(struct vm_area_struct
*vma
, unsigned long address
,
865 unsigned int foll_flags
)
867 struct follow_page_context ctx
= { NULL
};
870 if (vma_is_secretmem(vma
))
873 page
= follow_page_mask(vma
, address
, foll_flags
, &ctx
);
875 put_dev_pagemap(ctx
.pgmap
);
879 static int get_gate_page(struct mm_struct
*mm
, unsigned long address
,
880 unsigned int gup_flags
, struct vm_area_struct
**vma
,
890 /* user gate pages are read-only */
891 if (gup_flags
& FOLL_WRITE
)
893 if (address
> TASK_SIZE
)
894 pgd
= pgd_offset_k(address
);
896 pgd
= pgd_offset_gate(mm
, address
);
899 p4d
= p4d_offset(pgd
, address
);
902 pud
= pud_offset(p4d
, address
);
905 pmd
= pmd_offset(pud
, address
);
906 if (!pmd_present(*pmd
))
908 VM_BUG_ON(pmd_trans_huge(*pmd
));
909 pte
= pte_offset_map(pmd
, address
);
912 *vma
= get_gate_vma(mm
);
915 *page
= vm_normal_page(*vma
, address
, *pte
);
917 if ((gup_flags
& FOLL_DUMP
) || !is_zero_pfn(pte_pfn(*pte
)))
919 *page
= pte_page(*pte
);
921 if (unlikely(!try_grab_page(*page
, gup_flags
))) {
933 * mmap_lock must be held on entry. If @locked != NULL and *@flags
934 * does not include FOLL_NOWAIT, the mmap_lock may be released. If it
935 * is, *@locked will be set to 0 and -EBUSY returned.
937 static int faultin_page(struct vm_area_struct
*vma
,
938 unsigned long address
, unsigned int *flags
, int *locked
)
940 unsigned int fault_flags
= 0;
943 /* mlock all present pages, but do not fault in new pages */
944 if ((*flags
& (FOLL_POPULATE
| FOLL_MLOCK
)) == FOLL_MLOCK
)
946 if (*flags
& FOLL_NOFAULT
)
948 if (*flags
& FOLL_WRITE
)
949 fault_flags
|= FAULT_FLAG_WRITE
;
950 if (*flags
& FOLL_REMOTE
)
951 fault_flags
|= FAULT_FLAG_REMOTE
;
953 fault_flags
|= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
954 if (*flags
& FOLL_NOWAIT
)
955 fault_flags
|= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_RETRY_NOWAIT
;
956 if (*flags
& FOLL_TRIED
) {
958 * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED
961 fault_flags
|= FAULT_FLAG_TRIED
;
964 ret
= handle_mm_fault(vma
, address
, fault_flags
, NULL
);
965 if (ret
& VM_FAULT_ERROR
) {
966 int err
= vm_fault_to_errno(ret
, *flags
);
973 if (ret
& VM_FAULT_RETRY
) {
974 if (locked
&& !(fault_flags
& FAULT_FLAG_RETRY_NOWAIT
))
980 * The VM_FAULT_WRITE bit tells us that do_wp_page has broken COW when
981 * necessary, even if maybe_mkwrite decided not to set pte_write. We
982 * can thus safely do subsequent page lookups as if they were reads.
983 * But only do so when looping for pte_write is futile: in some cases
984 * userspace may also be wanting to write to the gotten user page,
985 * which a read fault here might prevent (a readonly page might get
986 * reCOWed by userspace write).
988 if ((ret
& VM_FAULT_WRITE
) && !(vma
->vm_flags
& VM_WRITE
))
993 static int check_vma_flags(struct vm_area_struct
*vma
, unsigned long gup_flags
)
995 vm_flags_t vm_flags
= vma
->vm_flags
;
996 int write
= (gup_flags
& FOLL_WRITE
);
997 int foreign
= (gup_flags
& FOLL_REMOTE
);
999 if (vm_flags
& (VM_IO
| VM_PFNMAP
))
1002 if (gup_flags
& FOLL_ANON
&& !vma_is_anonymous(vma
))
1005 if ((gup_flags
& FOLL_LONGTERM
) && vma_is_fsdax(vma
))
1008 if (vma_is_secretmem(vma
))
1012 if (!(vm_flags
& VM_WRITE
)) {
1013 if (!(gup_flags
& FOLL_FORCE
))
1016 * We used to let the write,force case do COW in a
1017 * VM_MAYWRITE VM_SHARED !VM_WRITE vma, so ptrace could
1018 * set a breakpoint in a read-only mapping of an
1019 * executable, without corrupting the file (yet only
1020 * when that file had been opened for writing!).
1021 * Anon pages in shared mappings are surprising: now
1024 if (!is_cow_mapping(vm_flags
))
1027 } else if (!(vm_flags
& VM_READ
)) {
1028 if (!(gup_flags
& FOLL_FORCE
))
1031 * Is there actually any vma we can reach here which does not
1032 * have VM_MAYREAD set?
1034 if (!(vm_flags
& VM_MAYREAD
))
1038 * gups are always data accesses, not instruction
1039 * fetches, so execute=false here
1041 if (!arch_vma_access_permitted(vma
, write
, false, foreign
))
1047 * __get_user_pages() - pin user pages in memory
1048 * @mm: mm_struct of target mm
1049 * @start: starting user address
1050 * @nr_pages: number of pages from start to pin
1051 * @gup_flags: flags modifying pin behaviour
1052 * @pages: array that receives pointers to the pages pinned.
1053 * Should be at least nr_pages long. Or NULL, if caller
1054 * only intends to ensure the pages are faulted in.
1055 * @vmas: array of pointers to vmas corresponding to each page.
1056 * Or NULL if the caller does not require them.
1057 * @locked: whether we're still with the mmap_lock held
1059 * Returns either number of pages pinned (which may be less than the
1060 * number requested), or an error. Details about the return value:
1062 * -- If nr_pages is 0, returns 0.
1063 * -- If nr_pages is >0, but no pages were pinned, returns -errno.
1064 * -- If nr_pages is >0, and some pages were pinned, returns the number of
1065 * pages pinned. Again, this may be less than nr_pages.
1066 * -- 0 return value is possible when the fault would need to be retried.
1068 * The caller is responsible for releasing returned @pages, via put_page().
1070 * @vmas are valid only as long as mmap_lock is held.
1072 * Must be called with mmap_lock held. It may be released. See below.
1074 * __get_user_pages walks a process's page tables and takes a reference to
1075 * each struct page that each user address corresponds to at a given
1076 * instant. That is, it takes the page that would be accessed if a user
1077 * thread accesses the given user virtual address at that instant.
1079 * This does not guarantee that the page exists in the user mappings when
1080 * __get_user_pages returns, and there may even be a completely different
1081 * page there in some cases (eg. if mmapped pagecache has been invalidated
1082 * and subsequently re faulted). However it does guarantee that the page
1083 * won't be freed completely. And mostly callers simply care that the page
1084 * contains data that was valid *at some point in time*. Typically, an IO
1085 * or similar operation cannot guarantee anything stronger anyway because
1086 * locks can't be held over the syscall boundary.
1088 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1089 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1090 * appropriate) must be called after the page is finished with, and
1091 * before put_page is called.
1093 * If @locked != NULL, *@locked will be set to 0 when mmap_lock is
1094 * released by an up_read(). That can happen if @gup_flags does not
1097 * A caller using such a combination of @locked and @gup_flags
1098 * must therefore hold the mmap_lock for reading only, and recognize
1099 * when it's been released. Otherwise, it must be held for either
1100 * reading or writing and will not be released.
1102 * In most cases, get_user_pages or get_user_pages_fast should be used
1103 * instead of __get_user_pages. __get_user_pages should be used only if
1104 * you need some special @gup_flags.
1106 static long __get_user_pages(struct mm_struct
*mm
,
1107 unsigned long start
, unsigned long nr_pages
,
1108 unsigned int gup_flags
, struct page
**pages
,
1109 struct vm_area_struct
**vmas
, int *locked
)
1111 long ret
= 0, i
= 0;
1112 struct vm_area_struct
*vma
= NULL
;
1113 struct follow_page_context ctx
= { NULL
};
1118 start
= untagged_addr(start
);
1120 VM_BUG_ON(!!pages
!= !!(gup_flags
& (FOLL_GET
| FOLL_PIN
)));
1123 * If FOLL_FORCE is set then do not force a full fault as the hinting
1124 * fault information is unrelated to the reference behaviour of a task
1125 * using the address space
1127 if (!(gup_flags
& FOLL_FORCE
))
1128 gup_flags
|= FOLL_NUMA
;
1132 unsigned int foll_flags
= gup_flags
;
1133 unsigned int page_increm
;
1135 /* first iteration or cross vma bound */
1136 if (!vma
|| start
>= vma
->vm_end
) {
1137 vma
= find_extend_vma(mm
, start
);
1138 if (!vma
&& in_gate_area(mm
, start
)) {
1139 ret
= get_gate_page(mm
, start
& PAGE_MASK
,
1141 pages
? &pages
[i
] : NULL
);
1152 ret
= check_vma_flags(vma
, gup_flags
);
1156 if (is_vm_hugetlb_page(vma
)) {
1157 i
= follow_hugetlb_page(mm
, vma
, pages
, vmas
,
1158 &start
, &nr_pages
, i
,
1160 if (locked
&& *locked
== 0) {
1162 * We've got a VM_FAULT_RETRY
1163 * and we've lost mmap_lock.
1164 * We must stop here.
1166 BUG_ON(gup_flags
& FOLL_NOWAIT
);
1174 * If we have a pending SIGKILL, don't keep faulting pages and
1175 * potentially allocating memory.
1177 if (fatal_signal_pending(current
)) {
1183 page
= follow_page_mask(vma
, start
, foll_flags
, &ctx
);
1185 ret
= faultin_page(vma
, start
, &foll_flags
, locked
);
1200 } else if (PTR_ERR(page
) == -EEXIST
) {
1202 * Proper page table entry exists, but no corresponding
1206 } else if (IS_ERR(page
)) {
1207 ret
= PTR_ERR(page
);
1212 flush_anon_page(vma
, page
, start
);
1213 flush_dcache_page(page
);
1221 page_increm
= 1 + (~(start
>> PAGE_SHIFT
) & ctx
.page_mask
);
1222 if (page_increm
> nr_pages
)
1223 page_increm
= nr_pages
;
1225 start
+= page_increm
* PAGE_SIZE
;
1226 nr_pages
-= page_increm
;
1230 put_dev_pagemap(ctx
.pgmap
);
1234 static bool vma_permits_fault(struct vm_area_struct
*vma
,
1235 unsigned int fault_flags
)
1237 bool write
= !!(fault_flags
& FAULT_FLAG_WRITE
);
1238 bool foreign
= !!(fault_flags
& FAULT_FLAG_REMOTE
);
1239 vm_flags_t vm_flags
= write
? VM_WRITE
: VM_READ
;
1241 if (!(vm_flags
& vma
->vm_flags
))
1245 * The architecture might have a hardware protection
1246 * mechanism other than read/write that can deny access.
1248 * gup always represents data access, not instruction
1249 * fetches, so execute=false here:
1251 if (!arch_vma_access_permitted(vma
, write
, false, foreign
))
1258 * fixup_user_fault() - manually resolve a user page fault
1259 * @mm: mm_struct of target mm
1260 * @address: user address
1261 * @fault_flags:flags to pass down to handle_mm_fault()
1262 * @unlocked: did we unlock the mmap_lock while retrying, maybe NULL if caller
1263 * does not allow retry. If NULL, the caller must guarantee
1264 * that fault_flags does not contain FAULT_FLAG_ALLOW_RETRY.
1266 * This is meant to be called in the specific scenario where for locking reasons
1267 * we try to access user memory in atomic context (within a pagefault_disable()
1268 * section), this returns -EFAULT, and we want to resolve the user fault before
1271 * Typically this is meant to be used by the futex code.
1273 * The main difference with get_user_pages() is that this function will
1274 * unconditionally call handle_mm_fault() which will in turn perform all the
1275 * necessary SW fixup of the dirty and young bits in the PTE, while
1276 * get_user_pages() only guarantees to update these in the struct page.
1278 * This is important for some architectures where those bits also gate the
1279 * access permission to the page because they are maintained in software. On
1280 * such architectures, gup() will not be enough to make a subsequent access
1283 * This function will not return with an unlocked mmap_lock. So it has not the
1284 * same semantics wrt the @mm->mmap_lock as does filemap_fault().
1286 int fixup_user_fault(struct mm_struct
*mm
,
1287 unsigned long address
, unsigned int fault_flags
,
1290 struct vm_area_struct
*vma
;
1293 address
= untagged_addr(address
);
1296 fault_flags
|= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
1299 vma
= find_extend_vma(mm
, address
);
1300 if (!vma
|| address
< vma
->vm_start
)
1303 if (!vma_permits_fault(vma
, fault_flags
))
1306 if ((fault_flags
& FAULT_FLAG_KILLABLE
) &&
1307 fatal_signal_pending(current
))
1310 ret
= handle_mm_fault(vma
, address
, fault_flags
, NULL
);
1311 if (ret
& VM_FAULT_ERROR
) {
1312 int err
= vm_fault_to_errno(ret
, 0);
1319 if (ret
& VM_FAULT_RETRY
) {
1322 fault_flags
|= FAULT_FLAG_TRIED
;
1328 EXPORT_SYMBOL_GPL(fixup_user_fault
);
1331 * Please note that this function, unlike __get_user_pages will not
1332 * return 0 for nr_pages > 0 without FOLL_NOWAIT
1334 static __always_inline
long __get_user_pages_locked(struct mm_struct
*mm
,
1335 unsigned long start
,
1336 unsigned long nr_pages
,
1337 struct page
**pages
,
1338 struct vm_area_struct
**vmas
,
1342 long ret
, pages_done
;
1346 /* if VM_FAULT_RETRY can be returned, vmas become invalid */
1348 /* check caller initialized locked */
1349 BUG_ON(*locked
!= 1);
1352 if (flags
& FOLL_PIN
)
1353 mm_set_has_pinned_flag(&mm
->flags
);
1356 * FOLL_PIN and FOLL_GET are mutually exclusive. Traditional behavior
1357 * is to set FOLL_GET if the caller wants pages[] filled in (but has
1358 * carelessly failed to specify FOLL_GET), so keep doing that, but only
1359 * for FOLL_GET, not for the newer FOLL_PIN.
1361 * FOLL_PIN always expects pages to be non-null, but no need to assert
1362 * that here, as any failures will be obvious enough.
1364 if (pages
&& !(flags
& FOLL_PIN
))
1368 lock_dropped
= false;
1370 ret
= __get_user_pages(mm
, start
, nr_pages
, flags
, pages
,
1373 /* VM_FAULT_RETRY couldn't trigger, bypass */
1376 /* VM_FAULT_RETRY cannot return errors */
1379 BUG_ON(ret
>= nr_pages
);
1390 * VM_FAULT_RETRY didn't trigger or it was a
1398 * VM_FAULT_RETRY triggered, so seek to the faulting offset.
1399 * For the prefault case (!pages) we only update counts.
1403 start
+= ret
<< PAGE_SHIFT
;
1404 lock_dropped
= true;
1408 * Repeat on the address that fired VM_FAULT_RETRY
1409 * with both FAULT_FLAG_ALLOW_RETRY and
1410 * FAULT_FLAG_TRIED. Note that GUP can be interrupted
1411 * by fatal signals, so we need to check it before we
1412 * start trying again otherwise it can loop forever.
1415 if (fatal_signal_pending(current
)) {
1417 pages_done
= -EINTR
;
1421 ret
= mmap_read_lock_killable(mm
);
1430 ret
= __get_user_pages(mm
, start
, 1, flags
| FOLL_TRIED
,
1431 pages
, NULL
, locked
);
1433 /* Continue to retry until we succeeded */
1451 if (lock_dropped
&& *locked
) {
1453 * We must let the caller know we temporarily dropped the lock
1454 * and so the critical section protected by it was lost.
1456 mmap_read_unlock(mm
);
1463 * populate_vma_page_range() - populate a range of pages in the vma.
1465 * @start: start address
1467 * @locked: whether the mmap_lock is still held
1469 * This takes care of mlocking the pages too if VM_LOCKED is set.
1471 * Return either number of pages pinned in the vma, or a negative error
1474 * vma->vm_mm->mmap_lock must be held.
1476 * If @locked is NULL, it may be held for read or write and will
1479 * If @locked is non-NULL, it must held for read only and may be
1480 * released. If it's released, *@locked will be set to 0.
1482 long populate_vma_page_range(struct vm_area_struct
*vma
,
1483 unsigned long start
, unsigned long end
, int *locked
)
1485 struct mm_struct
*mm
= vma
->vm_mm
;
1486 unsigned long nr_pages
= (end
- start
) / PAGE_SIZE
;
1489 VM_BUG_ON(!PAGE_ALIGNED(start
));
1490 VM_BUG_ON(!PAGE_ALIGNED(end
));
1491 VM_BUG_ON_VMA(start
< vma
->vm_start
, vma
);
1492 VM_BUG_ON_VMA(end
> vma
->vm_end
, vma
);
1493 mmap_assert_locked(mm
);
1495 gup_flags
= FOLL_TOUCH
| FOLL_POPULATE
| FOLL_MLOCK
;
1496 if (vma
->vm_flags
& VM_LOCKONFAULT
)
1497 gup_flags
&= ~FOLL_POPULATE
;
1499 * We want to touch writable mappings with a write fault in order
1500 * to break COW, except for shared mappings because these don't COW
1501 * and we would not want to dirty them for nothing.
1503 if ((vma
->vm_flags
& (VM_WRITE
| VM_SHARED
)) == VM_WRITE
)
1504 gup_flags
|= FOLL_WRITE
;
1507 * We want mlock to succeed for regions that have any permissions
1508 * other than PROT_NONE.
1510 if (vma_is_accessible(vma
))
1511 gup_flags
|= FOLL_FORCE
;
1514 * We made sure addr is within a VMA, so the following will
1515 * not result in a stack expansion that recurses back here.
1517 return __get_user_pages(mm
, start
, nr_pages
, gup_flags
,
1518 NULL
, NULL
, locked
);
1522 * faultin_vma_page_range() - populate (prefault) page tables inside the
1523 * given VMA range readable/writable
1525 * This takes care of mlocking the pages, too, if VM_LOCKED is set.
1528 * @start: start address
1530 * @write: whether to prefault readable or writable
1531 * @locked: whether the mmap_lock is still held
1533 * Returns either number of processed pages in the vma, or a negative error
1534 * code on error (see __get_user_pages()).
1536 * vma->vm_mm->mmap_lock must be held. The range must be page-aligned and
1537 * covered by the VMA.
1539 * If @locked is NULL, it may be held for read or write and will be unperturbed.
1541 * If @locked is non-NULL, it must held for read only and may be released. If
1542 * it's released, *@locked will be set to 0.
1544 long faultin_vma_page_range(struct vm_area_struct
*vma
, unsigned long start
,
1545 unsigned long end
, bool write
, int *locked
)
1547 struct mm_struct
*mm
= vma
->vm_mm
;
1548 unsigned long nr_pages
= (end
- start
) / PAGE_SIZE
;
1551 VM_BUG_ON(!PAGE_ALIGNED(start
));
1552 VM_BUG_ON(!PAGE_ALIGNED(end
));
1553 VM_BUG_ON_VMA(start
< vma
->vm_start
, vma
);
1554 VM_BUG_ON_VMA(end
> vma
->vm_end
, vma
);
1555 mmap_assert_locked(mm
);
1558 * FOLL_TOUCH: Mark page accessed and thereby young; will also mark
1559 * the page dirty with FOLL_WRITE -- which doesn't make a
1560 * difference with !FOLL_FORCE, because the page is writable
1561 * in the page table.
1562 * FOLL_HWPOISON: Return -EHWPOISON instead of -EFAULT when we hit
1564 * FOLL_POPULATE: Always populate memory with VM_LOCKONFAULT.
1565 * !FOLL_FORCE: Require proper access permissions.
1567 gup_flags
= FOLL_TOUCH
| FOLL_POPULATE
| FOLL_MLOCK
| FOLL_HWPOISON
;
1569 gup_flags
|= FOLL_WRITE
;
1572 * We want to report -EINVAL instead of -EFAULT for any permission
1573 * problems or incompatible mappings.
1575 if (check_vma_flags(vma
, gup_flags
))
1578 return __get_user_pages(mm
, start
, nr_pages
, gup_flags
,
1579 NULL
, NULL
, locked
);
1583 * __mm_populate - populate and/or mlock pages within a range of address space.
1585 * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
1586 * flags. VMAs must be already marked with the desired vm_flags, and
1587 * mmap_lock must not be held.
1589 int __mm_populate(unsigned long start
, unsigned long len
, int ignore_errors
)
1591 struct mm_struct
*mm
= current
->mm
;
1592 unsigned long end
, nstart
, nend
;
1593 struct vm_area_struct
*vma
= NULL
;
1599 for (nstart
= start
; nstart
< end
; nstart
= nend
) {
1601 * We want to fault in pages for [nstart; end) address range.
1602 * Find first corresponding VMA.
1607 vma
= find_vma(mm
, nstart
);
1608 } else if (nstart
>= vma
->vm_end
)
1610 if (!vma
|| vma
->vm_start
>= end
)
1613 * Set [nstart; nend) to intersection of desired address
1614 * range with the first VMA. Also, skip undesirable VMA types.
1616 nend
= min(end
, vma
->vm_end
);
1617 if (vma
->vm_flags
& (VM_IO
| VM_PFNMAP
))
1619 if (nstart
< vma
->vm_start
)
1620 nstart
= vma
->vm_start
;
1622 * Now fault in a range of pages. populate_vma_page_range()
1623 * double checks the vma flags, so that it won't mlock pages
1624 * if the vma was already munlocked.
1626 ret
= populate_vma_page_range(vma
, nstart
, nend
, &locked
);
1628 if (ignore_errors
) {
1630 continue; /* continue at next VMA */
1634 nend
= nstart
+ ret
* PAGE_SIZE
;
1638 mmap_read_unlock(mm
);
1639 return ret
; /* 0 or negative error code */
1641 #else /* CONFIG_MMU */
1642 static long __get_user_pages_locked(struct mm_struct
*mm
, unsigned long start
,
1643 unsigned long nr_pages
, struct page
**pages
,
1644 struct vm_area_struct
**vmas
, int *locked
,
1645 unsigned int foll_flags
)
1647 struct vm_area_struct
*vma
;
1648 unsigned long vm_flags
;
1651 /* calculate required read or write permissions.
1652 * If FOLL_FORCE is set, we only require the "MAY" flags.
1654 vm_flags
= (foll_flags
& FOLL_WRITE
) ?
1655 (VM_WRITE
| VM_MAYWRITE
) : (VM_READ
| VM_MAYREAD
);
1656 vm_flags
&= (foll_flags
& FOLL_FORCE
) ?
1657 (VM_MAYREAD
| VM_MAYWRITE
) : (VM_READ
| VM_WRITE
);
1659 for (i
= 0; i
< nr_pages
; i
++) {
1660 vma
= find_vma(mm
, start
);
1662 goto finish_or_fault
;
1664 /* protect what we can, including chardevs */
1665 if ((vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)) ||
1666 !(vm_flags
& vma
->vm_flags
))
1667 goto finish_or_fault
;
1670 pages
[i
] = virt_to_page(start
);
1676 start
= (start
+ PAGE_SIZE
) & PAGE_MASK
;
1682 return i
? : -EFAULT
;
1684 #endif /* !CONFIG_MMU */
1687 * fault_in_writeable - fault in userspace address range for writing
1688 * @uaddr: start of address range
1689 * @size: size of address range
1691 * Returns the number of bytes not faulted in (like copy_to_user() and
1692 * copy_from_user()).
1694 size_t fault_in_writeable(char __user
*uaddr
, size_t size
)
1696 char __user
*start
= uaddr
, *end
;
1698 if (unlikely(size
== 0))
1700 if (!PAGE_ALIGNED(uaddr
)) {
1701 if (unlikely(__put_user(0, uaddr
) != 0))
1703 uaddr
= (char __user
*)PAGE_ALIGN((unsigned long)uaddr
);
1705 end
= (char __user
*)PAGE_ALIGN((unsigned long)start
+ size
);
1706 if (unlikely(end
< start
))
1708 while (uaddr
!= end
) {
1709 if (unlikely(__put_user(0, uaddr
) != 0))
1715 if (size
> uaddr
- start
)
1716 return size
- (uaddr
- start
);
1719 EXPORT_SYMBOL(fault_in_writeable
);
1722 * fault_in_safe_writeable - fault in an address range for writing
1723 * @uaddr: start of address range
1724 * @size: length of address range
1726 * Faults in an address range for writing. This is primarily useful when we
1727 * already know that some or all of the pages in the address range aren't in
1730 * Unlike fault_in_writeable(), this function is non-destructive.
1732 * Note that we don't pin or otherwise hold the pages referenced that we fault
1733 * in. There's no guarantee that they'll stay in memory for any duration of
1736 * Returns the number of bytes not faulted in, like copy_to_user() and
1739 size_t fault_in_safe_writeable(const char __user
*uaddr
, size_t size
)
1741 unsigned long start
= (unsigned long)uaddr
, end
;
1742 struct mm_struct
*mm
= current
->mm
;
1743 bool unlocked
= false;
1745 if (unlikely(size
== 0))
1747 end
= PAGE_ALIGN(start
+ size
);
1753 if (fixup_user_fault(mm
, start
, FAULT_FLAG_WRITE
, &unlocked
))
1755 start
= (start
+ PAGE_SIZE
) & PAGE_MASK
;
1756 } while (start
!= end
);
1757 mmap_read_unlock(mm
);
1759 if (size
> (unsigned long)uaddr
- start
)
1760 return size
- ((unsigned long)uaddr
- start
);
1763 EXPORT_SYMBOL(fault_in_safe_writeable
);
1766 * fault_in_readable - fault in userspace address range for reading
1767 * @uaddr: start of user address range
1768 * @size: size of user address range
1770 * Returns the number of bytes not faulted in (like copy_to_user() and
1771 * copy_from_user()).
1773 size_t fault_in_readable(const char __user
*uaddr
, size_t size
)
1775 const char __user
*start
= uaddr
, *end
;
1778 if (unlikely(size
== 0))
1780 if (!PAGE_ALIGNED(uaddr
)) {
1781 if (unlikely(__get_user(c
, uaddr
) != 0))
1783 uaddr
= (const char __user
*)PAGE_ALIGN((unsigned long)uaddr
);
1785 end
= (const char __user
*)PAGE_ALIGN((unsigned long)start
+ size
);
1786 if (unlikely(end
< start
))
1788 while (uaddr
!= end
) {
1789 if (unlikely(__get_user(c
, uaddr
) != 0))
1796 if (size
> uaddr
- start
)
1797 return size
- (uaddr
- start
);
1800 EXPORT_SYMBOL(fault_in_readable
);
1803 * get_dump_page() - pin user page in memory while writing it to core dump
1804 * @addr: user address
1806 * Returns struct page pointer of user page pinned for dump,
1807 * to be freed afterwards by put_page().
1809 * Returns NULL on any kind of failure - a hole must then be inserted into
1810 * the corefile, to preserve alignment with its headers; and also returns
1811 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1812 * allowing a hole to be left in the corefile to save disk space.
1814 * Called without mmap_lock (takes and releases the mmap_lock by itself).
1816 #ifdef CONFIG_ELF_CORE
1817 struct page
*get_dump_page(unsigned long addr
)
1819 struct mm_struct
*mm
= current
->mm
;
1824 if (mmap_read_lock_killable(mm
))
1826 ret
= __get_user_pages_locked(mm
, addr
, 1, &page
, NULL
, &locked
,
1827 FOLL_FORCE
| FOLL_DUMP
| FOLL_GET
);
1829 mmap_read_unlock(mm
);
1830 return (ret
== 1) ? page
: NULL
;
1832 #endif /* CONFIG_ELF_CORE */
1834 #ifdef CONFIG_MIGRATION
1836 * Check whether all pages are pinnable, if so return number of pages. If some
1837 * pages are not pinnable, migrate them, and unpin all pages. Return zero if
1838 * pages were migrated, or if some pages were not successfully isolated.
1839 * Return negative error if migration fails.
1841 static long check_and_migrate_movable_pages(unsigned long nr_pages
,
1842 struct page
**pages
,
1843 unsigned int gup_flags
)
1846 unsigned long isolation_error_count
= 0;
1847 bool drain_allow
= true;
1848 LIST_HEAD(movable_page_list
);
1850 struct page
*prev_head
= NULL
;
1852 struct migration_target_control mtc
= {
1853 .nid
= NUMA_NO_NODE
,
1854 .gfp_mask
= GFP_USER
| __GFP_NOWARN
,
1857 for (i
= 0; i
< nr_pages
; i
++) {
1858 head
= compound_head(pages
[i
]);
1859 if (head
== prev_head
)
1863 * If we get a movable page, since we are going to be pinning
1864 * these entries, try to move them out if possible.
1866 if (!is_pinnable_page(head
)) {
1867 if (PageHuge(head
)) {
1868 if (!isolate_huge_page(head
, &movable_page_list
))
1869 isolation_error_count
++;
1871 if (!PageLRU(head
) && drain_allow
) {
1872 lru_add_drain_all();
1873 drain_allow
= false;
1876 if (isolate_lru_page(head
)) {
1877 isolation_error_count
++;
1880 list_add_tail(&head
->lru
, &movable_page_list
);
1881 mod_node_page_state(page_pgdat(head
),
1883 page_is_file_lru(head
),
1884 thp_nr_pages(head
));
1890 * If list is empty, and no isolation errors, means that all pages are
1891 * in the correct zone.
1893 if (list_empty(&movable_page_list
) && !isolation_error_count
)
1896 if (gup_flags
& FOLL_PIN
) {
1897 unpin_user_pages(pages
, nr_pages
);
1899 for (i
= 0; i
< nr_pages
; i
++)
1902 if (!list_empty(&movable_page_list
)) {
1903 ret
= migrate_pages(&movable_page_list
, alloc_migration_target
,
1904 NULL
, (unsigned long)&mtc
, MIGRATE_SYNC
,
1905 MR_LONGTERM_PIN
, NULL
);
1906 if (ret
&& !list_empty(&movable_page_list
))
1907 putback_movable_pages(&movable_page_list
);
1910 return ret
> 0 ? -ENOMEM
: ret
;
1913 static long check_and_migrate_movable_pages(unsigned long nr_pages
,
1914 struct page
**pages
,
1915 unsigned int gup_flags
)
1919 #endif /* CONFIG_MIGRATION */
1922 * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
1923 * allows us to process the FOLL_LONGTERM flag.
1925 static long __gup_longterm_locked(struct mm_struct
*mm
,
1926 unsigned long start
,
1927 unsigned long nr_pages
,
1928 struct page
**pages
,
1929 struct vm_area_struct
**vmas
,
1930 unsigned int gup_flags
)
1935 if (!(gup_flags
& FOLL_LONGTERM
))
1936 return __get_user_pages_locked(mm
, start
, nr_pages
, pages
, vmas
,
1938 flags
= memalloc_pin_save();
1940 rc
= __get_user_pages_locked(mm
, start
, nr_pages
, pages
, vmas
,
1944 rc
= check_and_migrate_movable_pages(rc
, pages
, gup_flags
);
1946 memalloc_pin_restore(flags
);
1951 static bool is_valid_gup_flags(unsigned int gup_flags
)
1954 * FOLL_PIN must only be set internally by the pin_user_pages*() APIs,
1955 * never directly by the caller, so enforce that with an assertion:
1957 if (WARN_ON_ONCE(gup_flags
& FOLL_PIN
))
1960 * FOLL_PIN is a prerequisite to FOLL_LONGTERM. Another way of saying
1961 * that is, FOLL_LONGTERM is a specific case, more restrictive case of
1964 if (WARN_ON_ONCE(gup_flags
& FOLL_LONGTERM
))
1971 static long __get_user_pages_remote(struct mm_struct
*mm
,
1972 unsigned long start
, unsigned long nr_pages
,
1973 unsigned int gup_flags
, struct page
**pages
,
1974 struct vm_area_struct
**vmas
, int *locked
)
1977 * Parts of FOLL_LONGTERM behavior are incompatible with
1978 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
1979 * vmas. However, this only comes up if locked is set, and there are
1980 * callers that do request FOLL_LONGTERM, but do not set locked. So,
1981 * allow what we can.
1983 if (gup_flags
& FOLL_LONGTERM
) {
1984 if (WARN_ON_ONCE(locked
))
1987 * This will check the vmas (even if our vmas arg is NULL)
1988 * and return -ENOTSUPP if DAX isn't allowed in this case:
1990 return __gup_longterm_locked(mm
, start
, nr_pages
, pages
,
1991 vmas
, gup_flags
| FOLL_TOUCH
|
1995 return __get_user_pages_locked(mm
, start
, nr_pages
, pages
, vmas
,
1997 gup_flags
| FOLL_TOUCH
| FOLL_REMOTE
);
2001 * get_user_pages_remote() - pin user pages in memory
2002 * @mm: mm_struct of target mm
2003 * @start: starting user address
2004 * @nr_pages: number of pages from start to pin
2005 * @gup_flags: flags modifying lookup behaviour
2006 * @pages: array that receives pointers to the pages pinned.
2007 * Should be at least nr_pages long. Or NULL, if caller
2008 * only intends to ensure the pages are faulted in.
2009 * @vmas: array of pointers to vmas corresponding to each page.
2010 * Or NULL if the caller does not require them.
2011 * @locked: pointer to lock flag indicating whether lock is held and
2012 * subsequently whether VM_FAULT_RETRY functionality can be
2013 * utilised. Lock must initially be held.
2015 * Returns either number of pages pinned (which may be less than the
2016 * number requested), or an error. Details about the return value:
2018 * -- If nr_pages is 0, returns 0.
2019 * -- If nr_pages is >0, but no pages were pinned, returns -errno.
2020 * -- If nr_pages is >0, and some pages were pinned, returns the number of
2021 * pages pinned. Again, this may be less than nr_pages.
2023 * The caller is responsible for releasing returned @pages, via put_page().
2025 * @vmas are valid only as long as mmap_lock is held.
2027 * Must be called with mmap_lock held for read or write.
2029 * get_user_pages_remote walks a process's page tables and takes a reference
2030 * to each struct page that each user address corresponds to at a given
2031 * instant. That is, it takes the page that would be accessed if a user
2032 * thread accesses the given user virtual address at that instant.
2034 * This does not guarantee that the page exists in the user mappings when
2035 * get_user_pages_remote returns, and there may even be a completely different
2036 * page there in some cases (eg. if mmapped pagecache has been invalidated
2037 * and subsequently re faulted). However it does guarantee that the page
2038 * won't be freed completely. And mostly callers simply care that the page
2039 * contains data that was valid *at some point in time*. Typically, an IO
2040 * or similar operation cannot guarantee anything stronger anyway because
2041 * locks can't be held over the syscall boundary.
2043 * If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page
2044 * is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must
2045 * be called after the page is finished with, and before put_page is called.
2047 * get_user_pages_remote is typically used for fewer-copy IO operations,
2048 * to get a handle on the memory by some means other than accesses
2049 * via the user virtual addresses. The pages may be submitted for
2050 * DMA to devices or accessed via their kernel linear mapping (via the
2051 * kmap APIs). Care should be taken to use the correct cache flushing APIs.
2053 * See also get_user_pages_fast, for performance critical applications.
2055 * get_user_pages_remote should be phased out in favor of
2056 * get_user_pages_locked|unlocked or get_user_pages_fast. Nothing
2057 * should use get_user_pages_remote because it cannot pass
2058 * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
2060 long get_user_pages_remote(struct mm_struct
*mm
,
2061 unsigned long start
, unsigned long nr_pages
,
2062 unsigned int gup_flags
, struct page
**pages
,
2063 struct vm_area_struct
**vmas
, int *locked
)
2065 if (!is_valid_gup_flags(gup_flags
))
2068 return __get_user_pages_remote(mm
, start
, nr_pages
, gup_flags
,
2069 pages
, vmas
, locked
);
2071 EXPORT_SYMBOL(get_user_pages_remote
);
2073 #else /* CONFIG_MMU */
2074 long get_user_pages_remote(struct mm_struct
*mm
,
2075 unsigned long start
, unsigned long nr_pages
,
2076 unsigned int gup_flags
, struct page
**pages
,
2077 struct vm_area_struct
**vmas
, int *locked
)
2082 static long __get_user_pages_remote(struct mm_struct
*mm
,
2083 unsigned long start
, unsigned long nr_pages
,
2084 unsigned int gup_flags
, struct page
**pages
,
2085 struct vm_area_struct
**vmas
, int *locked
)
2089 #endif /* !CONFIG_MMU */
2092 * get_user_pages() - pin user pages in memory
2093 * @start: starting user address
2094 * @nr_pages: number of pages from start to pin
2095 * @gup_flags: flags modifying lookup behaviour
2096 * @pages: array that receives pointers to the pages pinned.
2097 * Should be at least nr_pages long. Or NULL, if caller
2098 * only intends to ensure the pages are faulted in.
2099 * @vmas: array of pointers to vmas corresponding to each page.
2100 * Or NULL if the caller does not require them.
2102 * This is the same as get_user_pages_remote(), just with a less-flexible
2103 * calling convention where we assume that the mm being operated on belongs to
2104 * the current task, and doesn't allow passing of a locked parameter. We also
2105 * obviously don't pass FOLL_REMOTE in here.
2107 long get_user_pages(unsigned long start
, unsigned long nr_pages
,
2108 unsigned int gup_flags
, struct page
**pages
,
2109 struct vm_area_struct
**vmas
)
2111 if (!is_valid_gup_flags(gup_flags
))
2114 return __gup_longterm_locked(current
->mm
, start
, nr_pages
,
2115 pages
, vmas
, gup_flags
| FOLL_TOUCH
);
2117 EXPORT_SYMBOL(get_user_pages
);
2120 * get_user_pages_locked() - variant of get_user_pages()
2122 * @start: starting user address
2123 * @nr_pages: number of pages from start to pin
2124 * @gup_flags: flags modifying lookup behaviour
2125 * @pages: array that receives pointers to the pages pinned.
2126 * Should be at least nr_pages long. Or NULL, if caller
2127 * only intends to ensure the pages are faulted in.
2128 * @locked: pointer to lock flag indicating whether lock is held and
2129 * subsequently whether VM_FAULT_RETRY functionality can be
2130 * utilised. Lock must initially be held.
2132 * It is suitable to replace the form:
2134 * mmap_read_lock(mm);
2136 * get_user_pages(mm, ..., pages, NULL);
2137 * mmap_read_unlock(mm);
2142 * mmap_read_lock(mm);
2144 * get_user_pages_locked(mm, ..., pages, &locked);
2146 * mmap_read_unlock(mm);
2148 * We can leverage the VM_FAULT_RETRY functionality in the page fault
2149 * paths better by using either get_user_pages_locked() or
2150 * get_user_pages_unlocked().
2153 long get_user_pages_locked(unsigned long start
, unsigned long nr_pages
,
2154 unsigned int gup_flags
, struct page
**pages
,
2158 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
2159 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
2160 * vmas. As there are no users of this flag in this call we simply
2161 * disallow this option for now.
2163 if (WARN_ON_ONCE(gup_flags
& FOLL_LONGTERM
))
2166 * FOLL_PIN must only be set internally by the pin_user_pages*() APIs,
2167 * never directly by the caller, so enforce that:
2169 if (WARN_ON_ONCE(gup_flags
& FOLL_PIN
))
2172 return __get_user_pages_locked(current
->mm
, start
, nr_pages
,
2173 pages
, NULL
, locked
,
2174 gup_flags
| FOLL_TOUCH
);
2176 EXPORT_SYMBOL(get_user_pages_locked
);
2179 * get_user_pages_unlocked() is suitable to replace the form:
2181 * mmap_read_lock(mm);
2182 * get_user_pages(mm, ..., pages, NULL);
2183 * mmap_read_unlock(mm);
2187 * get_user_pages_unlocked(mm, ..., pages);
2189 * It is functionally equivalent to get_user_pages_fast so
2190 * get_user_pages_fast should be used instead if specific gup_flags
2191 * (e.g. FOLL_FORCE) are not required.
2193 long get_user_pages_unlocked(unsigned long start
, unsigned long nr_pages
,
2194 struct page
**pages
, unsigned int gup_flags
)
2196 struct mm_struct
*mm
= current
->mm
;
2201 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
2202 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
2203 * vmas. As there are no users of this flag in this call we simply
2204 * disallow this option for now.
2206 if (WARN_ON_ONCE(gup_flags
& FOLL_LONGTERM
))
2210 ret
= __get_user_pages_locked(mm
, start
, nr_pages
, pages
, NULL
,
2211 &locked
, gup_flags
| FOLL_TOUCH
);
2213 mmap_read_unlock(mm
);
2216 EXPORT_SYMBOL(get_user_pages_unlocked
);
2221 * get_user_pages_fast attempts to pin user pages by walking the page
2222 * tables directly and avoids taking locks. Thus the walker needs to be
2223 * protected from page table pages being freed from under it, and should
2224 * block any THP splits.
2226 * One way to achieve this is to have the walker disable interrupts, and
2227 * rely on IPIs from the TLB flushing code blocking before the page table
2228 * pages are freed. This is unsuitable for architectures that do not need
2229 * to broadcast an IPI when invalidating TLBs.
2231 * Another way to achieve this is to batch up page table containing pages
2232 * belonging to more than one mm_user, then rcu_sched a callback to free those
2233 * pages. Disabling interrupts will allow the fast_gup walker to both block
2234 * the rcu_sched callback, and an IPI that we broadcast for splitting THPs
2235 * (which is a relatively rare event). The code below adopts this strategy.
2237 * Before activating this code, please be aware that the following assumptions
2238 * are currently made:
2240 * *) Either MMU_GATHER_RCU_TABLE_FREE is enabled, and tlb_remove_table() is used to
2241 * free pages containing page tables or TLB flushing requires IPI broadcast.
2243 * *) ptes can be read atomically by the architecture.
2245 * *) access_ok is sufficient to validate userspace address ranges.
2247 * The last two assumptions can be relaxed by the addition of helper functions.
2249 * This code is based heavily on the PowerPC implementation by Nick Piggin.
2251 #ifdef CONFIG_HAVE_FAST_GUP
2253 static void __maybe_unused
undo_dev_pagemap(int *nr
, int nr_start
,
2255 struct page
**pages
)
2257 while ((*nr
) - nr_start
) {
2258 struct page
*page
= pages
[--(*nr
)];
2260 ClearPageReferenced(page
);
2261 if (flags
& FOLL_PIN
)
2262 unpin_user_page(page
);
2268 #ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
2269 static int gup_pte_range(pmd_t pmd
, unsigned long addr
, unsigned long end
,
2270 unsigned int flags
, struct page
**pages
, int *nr
)
2272 struct dev_pagemap
*pgmap
= NULL
;
2273 int nr_start
= *nr
, ret
= 0;
2276 ptem
= ptep
= pte_offset_map(&pmd
, addr
);
2278 pte_t pte
= ptep_get_lockless(ptep
);
2279 struct page
*head
, *page
;
2282 * Similar to the PMD case below, NUMA hinting must take slow
2283 * path using the pte_protnone check.
2285 if (pte_protnone(pte
))
2288 if (!pte_access_permitted(pte
, flags
& FOLL_WRITE
))
2291 if (pte_devmap(pte
)) {
2292 if (unlikely(flags
& FOLL_LONGTERM
))
2295 pgmap
= get_dev_pagemap(pte_pfn(pte
), pgmap
);
2296 if (unlikely(!pgmap
)) {
2297 undo_dev_pagemap(nr
, nr_start
, flags
, pages
);
2300 } else if (pte_special(pte
))
2303 VM_BUG_ON(!pfn_valid(pte_pfn(pte
)));
2304 page
= pte_page(pte
);
2306 head
= try_grab_compound_head(page
, 1, flags
);
2310 if (unlikely(page_is_secretmem(page
))) {
2311 put_compound_head(head
, 1, flags
);
2315 if (unlikely(pte_val(pte
) != pte_val(*ptep
))) {
2316 put_compound_head(head
, 1, flags
);
2320 VM_BUG_ON_PAGE(compound_head(page
) != head
, page
);
2323 * We need to make the page accessible if and only if we are
2324 * going to access its content (the FOLL_PIN case). Please
2325 * see Documentation/core-api/pin_user_pages.rst for
2328 if (flags
& FOLL_PIN
) {
2329 ret
= arch_make_page_accessible(page
);
2331 unpin_user_page(page
);
2335 SetPageReferenced(page
);
2339 } while (ptep
++, addr
+= PAGE_SIZE
, addr
!= end
);
2345 put_dev_pagemap(pgmap
);
2352 * If we can't determine whether or not a pte is special, then fail immediately
2353 * for ptes. Note, we can still pin HugeTLB and THP as these are guaranteed not
2356 * For a futex to be placed on a THP tail page, get_futex_key requires a
2357 * get_user_pages_fast_only implementation that can pin pages. Thus it's still
2358 * useful to have gup_huge_pmd even if we can't operate on ptes.
2360 static int gup_pte_range(pmd_t pmd
, unsigned long addr
, unsigned long end
,
2361 unsigned int flags
, struct page
**pages
, int *nr
)
2365 #endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */
2367 #if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
2368 static int __gup_device_huge(unsigned long pfn
, unsigned long addr
,
2369 unsigned long end
, unsigned int flags
,
2370 struct page
**pages
, int *nr
)
2373 struct dev_pagemap
*pgmap
= NULL
;
2377 struct page
*page
= pfn_to_page(pfn
);
2379 pgmap
= get_dev_pagemap(pfn
, pgmap
);
2380 if (unlikely(!pgmap
)) {
2381 undo_dev_pagemap(nr
, nr_start
, flags
, pages
);
2385 SetPageReferenced(page
);
2387 if (unlikely(!try_grab_page(page
, flags
))) {
2388 undo_dev_pagemap(nr
, nr_start
, flags
, pages
);
2394 } while (addr
+= PAGE_SIZE
, addr
!= end
);
2396 put_dev_pagemap(pgmap
);
2400 static int __gup_device_huge_pmd(pmd_t orig
, pmd_t
*pmdp
, unsigned long addr
,
2401 unsigned long end
, unsigned int flags
,
2402 struct page
**pages
, int *nr
)
2404 unsigned long fault_pfn
;
2407 fault_pfn
= pmd_pfn(orig
) + ((addr
& ~PMD_MASK
) >> PAGE_SHIFT
);
2408 if (!__gup_device_huge(fault_pfn
, addr
, end
, flags
, pages
, nr
))
2411 if (unlikely(pmd_val(orig
) != pmd_val(*pmdp
))) {
2412 undo_dev_pagemap(nr
, nr_start
, flags
, pages
);
2418 static int __gup_device_huge_pud(pud_t orig
, pud_t
*pudp
, unsigned long addr
,
2419 unsigned long end
, unsigned int flags
,
2420 struct page
**pages
, int *nr
)
2422 unsigned long fault_pfn
;
2425 fault_pfn
= pud_pfn(orig
) + ((addr
& ~PUD_MASK
) >> PAGE_SHIFT
);
2426 if (!__gup_device_huge(fault_pfn
, addr
, end
, flags
, pages
, nr
))
2429 if (unlikely(pud_val(orig
) != pud_val(*pudp
))) {
2430 undo_dev_pagemap(nr
, nr_start
, flags
, pages
);
2436 static int __gup_device_huge_pmd(pmd_t orig
, pmd_t
*pmdp
, unsigned long addr
,
2437 unsigned long end
, unsigned int flags
,
2438 struct page
**pages
, int *nr
)
2444 static int __gup_device_huge_pud(pud_t pud
, pud_t
*pudp
, unsigned long addr
,
2445 unsigned long end
, unsigned int flags
,
2446 struct page
**pages
, int *nr
)
2453 static int record_subpages(struct page
*page
, unsigned long addr
,
2454 unsigned long end
, struct page
**pages
)
2458 for (nr
= 0; addr
!= end
; addr
+= PAGE_SIZE
)
2459 pages
[nr
++] = page
++;
2464 #ifdef CONFIG_ARCH_HAS_HUGEPD
2465 static unsigned long hugepte_addr_end(unsigned long addr
, unsigned long end
,
2468 unsigned long __boundary
= (addr
+ sz
) & ~(sz
-1);
2469 return (__boundary
- 1 < end
- 1) ? __boundary
: end
;
2472 static int gup_hugepte(pte_t
*ptep
, unsigned long sz
, unsigned long addr
,
2473 unsigned long end
, unsigned int flags
,
2474 struct page
**pages
, int *nr
)
2476 unsigned long pte_end
;
2477 struct page
*head
, *page
;
2481 pte_end
= (addr
+ sz
) & ~(sz
-1);
2485 pte
= huge_ptep_get(ptep
);
2487 if (!pte_access_permitted(pte
, flags
& FOLL_WRITE
))
2490 /* hugepages are never "special" */
2491 VM_BUG_ON(!pfn_valid(pte_pfn(pte
)));
2493 head
= pte_page(pte
);
2494 page
= head
+ ((addr
& (sz
-1)) >> PAGE_SHIFT
);
2495 refs
= record_subpages(page
, addr
, end
, pages
+ *nr
);
2497 head
= try_grab_compound_head(head
, refs
, flags
);
2501 if (unlikely(pte_val(pte
) != pte_val(*ptep
))) {
2502 put_compound_head(head
, refs
, flags
);
2507 SetPageReferenced(head
);
2511 static int gup_huge_pd(hugepd_t hugepd
, unsigned long addr
,
2512 unsigned int pdshift
, unsigned long end
, unsigned int flags
,
2513 struct page
**pages
, int *nr
)
2516 unsigned long sz
= 1UL << hugepd_shift(hugepd
);
2519 ptep
= hugepte_offset(hugepd
, addr
, pdshift
);
2521 next
= hugepte_addr_end(addr
, end
, sz
);
2522 if (!gup_hugepte(ptep
, sz
, addr
, end
, flags
, pages
, nr
))
2524 } while (ptep
++, addr
= next
, addr
!= end
);
2529 static inline int gup_huge_pd(hugepd_t hugepd
, unsigned long addr
,
2530 unsigned int pdshift
, unsigned long end
, unsigned int flags
,
2531 struct page
**pages
, int *nr
)
2535 #endif /* CONFIG_ARCH_HAS_HUGEPD */
2537 static int gup_huge_pmd(pmd_t orig
, pmd_t
*pmdp
, unsigned long addr
,
2538 unsigned long end
, unsigned int flags
,
2539 struct page
**pages
, int *nr
)
2541 struct page
*head
, *page
;
2544 if (!pmd_access_permitted(orig
, flags
& FOLL_WRITE
))
2547 if (pmd_devmap(orig
)) {
2548 if (unlikely(flags
& FOLL_LONGTERM
))
2550 return __gup_device_huge_pmd(orig
, pmdp
, addr
, end
, flags
,
2554 page
= pmd_page(orig
) + ((addr
& ~PMD_MASK
) >> PAGE_SHIFT
);
2555 refs
= record_subpages(page
, addr
, end
, pages
+ *nr
);
2557 head
= try_grab_compound_head(pmd_page(orig
), refs
, flags
);
2561 if (unlikely(pmd_val(orig
) != pmd_val(*pmdp
))) {
2562 put_compound_head(head
, refs
, flags
);
2567 SetPageReferenced(head
);
2571 static int gup_huge_pud(pud_t orig
, pud_t
*pudp
, unsigned long addr
,
2572 unsigned long end
, unsigned int flags
,
2573 struct page
**pages
, int *nr
)
2575 struct page
*head
, *page
;
2578 if (!pud_access_permitted(orig
, flags
& FOLL_WRITE
))
2581 if (pud_devmap(orig
)) {
2582 if (unlikely(flags
& FOLL_LONGTERM
))
2584 return __gup_device_huge_pud(orig
, pudp
, addr
, end
, flags
,
2588 page
= pud_page(orig
) + ((addr
& ~PUD_MASK
) >> PAGE_SHIFT
);
2589 refs
= record_subpages(page
, addr
, end
, pages
+ *nr
);
2591 head
= try_grab_compound_head(pud_page(orig
), refs
, flags
);
2595 if (unlikely(pud_val(orig
) != pud_val(*pudp
))) {
2596 put_compound_head(head
, refs
, flags
);
2601 SetPageReferenced(head
);
2605 static int gup_huge_pgd(pgd_t orig
, pgd_t
*pgdp
, unsigned long addr
,
2606 unsigned long end
, unsigned int flags
,
2607 struct page
**pages
, int *nr
)
2610 struct page
*head
, *page
;
2612 if (!pgd_access_permitted(orig
, flags
& FOLL_WRITE
))
2615 BUILD_BUG_ON(pgd_devmap(orig
));
2617 page
= pgd_page(orig
) + ((addr
& ~PGDIR_MASK
) >> PAGE_SHIFT
);
2618 refs
= record_subpages(page
, addr
, end
, pages
+ *nr
);
2620 head
= try_grab_compound_head(pgd_page(orig
), refs
, flags
);
2624 if (unlikely(pgd_val(orig
) != pgd_val(*pgdp
))) {
2625 put_compound_head(head
, refs
, flags
);
2630 SetPageReferenced(head
);
2634 static int gup_pmd_range(pud_t
*pudp
, pud_t pud
, unsigned long addr
, unsigned long end
,
2635 unsigned int flags
, struct page
**pages
, int *nr
)
2640 pmdp
= pmd_offset_lockless(pudp
, pud
, addr
);
2642 pmd_t pmd
= READ_ONCE(*pmdp
);
2644 next
= pmd_addr_end(addr
, end
);
2645 if (!pmd_present(pmd
))
2648 if (unlikely(pmd_trans_huge(pmd
) || pmd_huge(pmd
) ||
2651 * NUMA hinting faults need to be handled in the GUP
2652 * slowpath for accounting purposes and so that they
2653 * can be serialised against THP migration.
2655 if (pmd_protnone(pmd
))
2658 if (!gup_huge_pmd(pmd
, pmdp
, addr
, next
, flags
,
2662 } else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd
))))) {
2664 * architecture have different format for hugetlbfs
2665 * pmd format and THP pmd format
2667 if (!gup_huge_pd(__hugepd(pmd_val(pmd
)), addr
,
2668 PMD_SHIFT
, next
, flags
, pages
, nr
))
2670 } else if (!gup_pte_range(pmd
, addr
, next
, flags
, pages
, nr
))
2672 } while (pmdp
++, addr
= next
, addr
!= end
);
2677 static int gup_pud_range(p4d_t
*p4dp
, p4d_t p4d
, unsigned long addr
, unsigned long end
,
2678 unsigned int flags
, struct page
**pages
, int *nr
)
2683 pudp
= pud_offset_lockless(p4dp
, p4d
, addr
);
2685 pud_t pud
= READ_ONCE(*pudp
);
2687 next
= pud_addr_end(addr
, end
);
2688 if (unlikely(!pud_present(pud
)))
2690 if (unlikely(pud_huge(pud
))) {
2691 if (!gup_huge_pud(pud
, pudp
, addr
, next
, flags
,
2694 } else if (unlikely(is_hugepd(__hugepd(pud_val(pud
))))) {
2695 if (!gup_huge_pd(__hugepd(pud_val(pud
)), addr
,
2696 PUD_SHIFT
, next
, flags
, pages
, nr
))
2698 } else if (!gup_pmd_range(pudp
, pud
, addr
, next
, flags
, pages
, nr
))
2700 } while (pudp
++, addr
= next
, addr
!= end
);
2705 static int gup_p4d_range(pgd_t
*pgdp
, pgd_t pgd
, unsigned long addr
, unsigned long end
,
2706 unsigned int flags
, struct page
**pages
, int *nr
)
2711 p4dp
= p4d_offset_lockless(pgdp
, pgd
, addr
);
2713 p4d_t p4d
= READ_ONCE(*p4dp
);
2715 next
= p4d_addr_end(addr
, end
);
2718 BUILD_BUG_ON(p4d_huge(p4d
));
2719 if (unlikely(is_hugepd(__hugepd(p4d_val(p4d
))))) {
2720 if (!gup_huge_pd(__hugepd(p4d_val(p4d
)), addr
,
2721 P4D_SHIFT
, next
, flags
, pages
, nr
))
2723 } else if (!gup_pud_range(p4dp
, p4d
, addr
, next
, flags
, pages
, nr
))
2725 } while (p4dp
++, addr
= next
, addr
!= end
);
2730 static void gup_pgd_range(unsigned long addr
, unsigned long end
,
2731 unsigned int flags
, struct page
**pages
, int *nr
)
2736 pgdp
= pgd_offset(current
->mm
, addr
);
2738 pgd_t pgd
= READ_ONCE(*pgdp
);
2740 next
= pgd_addr_end(addr
, end
);
2743 if (unlikely(pgd_huge(pgd
))) {
2744 if (!gup_huge_pgd(pgd
, pgdp
, addr
, next
, flags
,
2747 } else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd
))))) {
2748 if (!gup_huge_pd(__hugepd(pgd_val(pgd
)), addr
,
2749 PGDIR_SHIFT
, next
, flags
, pages
, nr
))
2751 } else if (!gup_p4d_range(pgdp
, pgd
, addr
, next
, flags
, pages
, nr
))
2753 } while (pgdp
++, addr
= next
, addr
!= end
);
2756 static inline void gup_pgd_range(unsigned long addr
, unsigned long end
,
2757 unsigned int flags
, struct page
**pages
, int *nr
)
2760 #endif /* CONFIG_HAVE_FAST_GUP */
2762 #ifndef gup_fast_permitted
2764 * Check if it's allowed to use get_user_pages_fast_only() for the range, or
2765 * we need to fall back to the slow version:
2767 static bool gup_fast_permitted(unsigned long start
, unsigned long end
)
2773 static int __gup_longterm_unlocked(unsigned long start
, int nr_pages
,
2774 unsigned int gup_flags
, struct page
**pages
)
2779 * FIXME: FOLL_LONGTERM does not work with
2780 * get_user_pages_unlocked() (see comments in that function)
2782 if (gup_flags
& FOLL_LONGTERM
) {
2783 mmap_read_lock(current
->mm
);
2784 ret
= __gup_longterm_locked(current
->mm
,
2786 pages
, NULL
, gup_flags
);
2787 mmap_read_unlock(current
->mm
);
2789 ret
= get_user_pages_unlocked(start
, nr_pages
,
2796 static unsigned long lockless_pages_from_mm(unsigned long start
,
2798 unsigned int gup_flags
,
2799 struct page
**pages
)
2801 unsigned long flags
;
2805 if (!IS_ENABLED(CONFIG_HAVE_FAST_GUP
) ||
2806 !gup_fast_permitted(start
, end
))
2809 if (gup_flags
& FOLL_PIN
) {
2810 seq
= raw_read_seqcount(¤t
->mm
->write_protect_seq
);
2816 * Disable interrupts. The nested form is used, in order to allow full,
2817 * general purpose use of this routine.
2819 * With interrupts disabled, we block page table pages from being freed
2820 * from under us. See struct mmu_table_batch comments in
2821 * include/asm-generic/tlb.h for more details.
2823 * We do not adopt an rcu_read_lock() here as we also want to block IPIs
2824 * that come from THPs splitting.
2826 local_irq_save(flags
);
2827 gup_pgd_range(start
, end
, gup_flags
, pages
, &nr_pinned
);
2828 local_irq_restore(flags
);
2831 * When pinning pages for DMA there could be a concurrent write protect
2832 * from fork() via copy_page_range(), in this case always fail fast GUP.
2834 if (gup_flags
& FOLL_PIN
) {
2835 if (read_seqcount_retry(¤t
->mm
->write_protect_seq
, seq
)) {
2836 unpin_user_pages(pages
, nr_pinned
);
2843 static int internal_get_user_pages_fast(unsigned long start
,
2844 unsigned long nr_pages
,
2845 unsigned int gup_flags
,
2846 struct page
**pages
)
2848 unsigned long len
, end
;
2849 unsigned long nr_pinned
;
2852 if (WARN_ON_ONCE(gup_flags
& ~(FOLL_WRITE
| FOLL_LONGTERM
|
2853 FOLL_FORCE
| FOLL_PIN
| FOLL_GET
|
2854 FOLL_FAST_ONLY
| FOLL_NOFAULT
)))
2857 if (gup_flags
& FOLL_PIN
)
2858 mm_set_has_pinned_flag(¤t
->mm
->flags
);
2860 if (!(gup_flags
& FOLL_FAST_ONLY
))
2861 might_lock_read(¤t
->mm
->mmap_lock
);
2863 start
= untagged_addr(start
) & PAGE_MASK
;
2864 len
= nr_pages
<< PAGE_SHIFT
;
2865 if (check_add_overflow(start
, len
, &end
))
2867 if (unlikely(!access_ok((void __user
*)start
, len
)))
2870 nr_pinned
= lockless_pages_from_mm(start
, end
, gup_flags
, pages
);
2871 if (nr_pinned
== nr_pages
|| gup_flags
& FOLL_FAST_ONLY
)
2874 /* Slow path: try to get the remaining pages with get_user_pages */
2875 start
+= nr_pinned
<< PAGE_SHIFT
;
2877 ret
= __gup_longterm_unlocked(start
, nr_pages
- nr_pinned
, gup_flags
,
2881 * The caller has to unpin the pages we already pinned so
2882 * returning -errno is not an option
2888 return ret
+ nr_pinned
;
2892 * get_user_pages_fast_only() - pin user pages in memory
2893 * @start: starting user address
2894 * @nr_pages: number of pages from start to pin
2895 * @gup_flags: flags modifying pin behaviour
2896 * @pages: array that receives pointers to the pages pinned.
2897 * Should be at least nr_pages long.
2899 * Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
2901 * Note a difference with get_user_pages_fast: this always returns the
2902 * number of pages pinned, 0 if no pages were pinned.
2904 * If the architecture does not support this function, simply return with no
2907 * Careful, careful! COW breaking can go either way, so a non-write
2908 * access can get ambiguous page results. If you call this function without
2909 * 'write' set, you'd better be sure that you're ok with that ambiguity.
2911 int get_user_pages_fast_only(unsigned long start
, int nr_pages
,
2912 unsigned int gup_flags
, struct page
**pages
)
2916 * Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
2917 * because gup fast is always a "pin with a +1 page refcount" request.
2919 * FOLL_FAST_ONLY is required in order to match the API description of
2920 * this routine: no fall back to regular ("slow") GUP.
2922 gup_flags
|= FOLL_GET
| FOLL_FAST_ONLY
;
2924 nr_pinned
= internal_get_user_pages_fast(start
, nr_pages
, gup_flags
,
2928 * As specified in the API description above, this routine is not
2929 * allowed to return negative values. However, the common core
2930 * routine internal_get_user_pages_fast() *can* return -errno.
2931 * Therefore, correct for that here:
2938 EXPORT_SYMBOL_GPL(get_user_pages_fast_only
);
2941 * get_user_pages_fast() - pin user pages in memory
2942 * @start: starting user address
2943 * @nr_pages: number of pages from start to pin
2944 * @gup_flags: flags modifying pin behaviour
2945 * @pages: array that receives pointers to the pages pinned.
2946 * Should be at least nr_pages long.
2948 * Attempt to pin user pages in memory without taking mm->mmap_lock.
2949 * If not successful, it will fall back to taking the lock and
2950 * calling get_user_pages().
2952 * Returns number of pages pinned. This may be fewer than the number requested.
2953 * If nr_pages is 0 or negative, returns 0. If no pages were pinned, returns
2956 int get_user_pages_fast(unsigned long start
, int nr_pages
,
2957 unsigned int gup_flags
, struct page
**pages
)
2959 if (!is_valid_gup_flags(gup_flags
))
2963 * The caller may or may not have explicitly set FOLL_GET; either way is
2964 * OK. However, internally (within mm/gup.c), gup fast variants must set
2965 * FOLL_GET, because gup fast is always a "pin with a +1 page refcount"
2968 gup_flags
|= FOLL_GET
;
2969 return internal_get_user_pages_fast(start
, nr_pages
, gup_flags
, pages
);
2971 EXPORT_SYMBOL_GPL(get_user_pages_fast
);
2974 * pin_user_pages_fast() - pin user pages in memory without taking locks
2976 * @start: starting user address
2977 * @nr_pages: number of pages from start to pin
2978 * @gup_flags: flags modifying pin behaviour
2979 * @pages: array that receives pointers to the pages pinned.
2980 * Should be at least nr_pages long.
2982 * Nearly the same as get_user_pages_fast(), except that FOLL_PIN is set. See
2983 * get_user_pages_fast() for documentation on the function arguments, because
2984 * the arguments here are identical.
2986 * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
2987 * see Documentation/core-api/pin_user_pages.rst for further details.
2989 int pin_user_pages_fast(unsigned long start
, int nr_pages
,
2990 unsigned int gup_flags
, struct page
**pages
)
2992 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
2993 if (WARN_ON_ONCE(gup_flags
& FOLL_GET
))
2996 gup_flags
|= FOLL_PIN
;
2997 return internal_get_user_pages_fast(start
, nr_pages
, gup_flags
, pages
);
2999 EXPORT_SYMBOL_GPL(pin_user_pages_fast
);
3002 * This is the FOLL_PIN equivalent of get_user_pages_fast_only(). Behavior
3003 * is the same, except that this one sets FOLL_PIN instead of FOLL_GET.
3005 * The API rules are the same, too: no negative values may be returned.
3007 int pin_user_pages_fast_only(unsigned long start
, int nr_pages
,
3008 unsigned int gup_flags
, struct page
**pages
)
3013 * FOLL_GET and FOLL_PIN are mutually exclusive. Note that the API
3014 * rules require returning 0, rather than -errno:
3016 if (WARN_ON_ONCE(gup_flags
& FOLL_GET
))
3019 * FOLL_FAST_ONLY is required in order to match the API description of
3020 * this routine: no fall back to regular ("slow") GUP.
3022 gup_flags
|= (FOLL_PIN
| FOLL_FAST_ONLY
);
3023 nr_pinned
= internal_get_user_pages_fast(start
, nr_pages
, gup_flags
,
3026 * This routine is not allowed to return negative values. However,
3027 * internal_get_user_pages_fast() *can* return -errno. Therefore,
3028 * correct for that here:
3035 EXPORT_SYMBOL_GPL(pin_user_pages_fast_only
);
3038 * pin_user_pages_remote() - pin pages of a remote process
3040 * @mm: mm_struct of target mm
3041 * @start: starting user address
3042 * @nr_pages: number of pages from start to pin
3043 * @gup_flags: flags modifying lookup behaviour
3044 * @pages: array that receives pointers to the pages pinned.
3045 * Should be at least nr_pages long. Or NULL, if caller
3046 * only intends to ensure the pages are faulted in.
3047 * @vmas: array of pointers to vmas corresponding to each page.
3048 * Or NULL if the caller does not require them.
3049 * @locked: pointer to lock flag indicating whether lock is held and
3050 * subsequently whether VM_FAULT_RETRY functionality can be
3051 * utilised. Lock must initially be held.
3053 * Nearly the same as get_user_pages_remote(), except that FOLL_PIN is set. See
3054 * get_user_pages_remote() for documentation on the function arguments, because
3055 * the arguments here are identical.
3057 * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
3058 * see Documentation/core-api/pin_user_pages.rst for details.
3060 long pin_user_pages_remote(struct mm_struct
*mm
,
3061 unsigned long start
, unsigned long nr_pages
,
3062 unsigned int gup_flags
, struct page
**pages
,
3063 struct vm_area_struct
**vmas
, int *locked
)
3065 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
3066 if (WARN_ON_ONCE(gup_flags
& FOLL_GET
))
3069 gup_flags
|= FOLL_PIN
;
3070 return __get_user_pages_remote(mm
, start
, nr_pages
, gup_flags
,
3071 pages
, vmas
, locked
);
3073 EXPORT_SYMBOL(pin_user_pages_remote
);
3076 * pin_user_pages() - pin user pages in memory for use by other devices
3078 * @start: starting user address
3079 * @nr_pages: number of pages from start to pin
3080 * @gup_flags: flags modifying lookup behaviour
3081 * @pages: array that receives pointers to the pages pinned.
3082 * Should be at least nr_pages long. Or NULL, if caller
3083 * only intends to ensure the pages are faulted in.
3084 * @vmas: array of pointers to vmas corresponding to each page.
3085 * Or NULL if the caller does not require them.
3087 * Nearly the same as get_user_pages(), except that FOLL_TOUCH is not set, and
3090 * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
3091 * see Documentation/core-api/pin_user_pages.rst for details.
3093 long pin_user_pages(unsigned long start
, unsigned long nr_pages
,
3094 unsigned int gup_flags
, struct page
**pages
,
3095 struct vm_area_struct
**vmas
)
3097 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
3098 if (WARN_ON_ONCE(gup_flags
& FOLL_GET
))
3101 gup_flags
|= FOLL_PIN
;
3102 return __gup_longterm_locked(current
->mm
, start
, nr_pages
,
3103 pages
, vmas
, gup_flags
);
3105 EXPORT_SYMBOL(pin_user_pages
);
3108 * pin_user_pages_unlocked() is the FOLL_PIN variant of
3109 * get_user_pages_unlocked(). Behavior is the same, except that this one sets
3110 * FOLL_PIN and rejects FOLL_GET.
3112 long pin_user_pages_unlocked(unsigned long start
, unsigned long nr_pages
,
3113 struct page
**pages
, unsigned int gup_flags
)
3115 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
3116 if (WARN_ON_ONCE(gup_flags
& FOLL_GET
))
3119 gup_flags
|= FOLL_PIN
;
3120 return get_user_pages_unlocked(start
, nr_pages
, pages
, gup_flags
);
3122 EXPORT_SYMBOL(pin_user_pages_unlocked
);
3125 * pin_user_pages_locked() is the FOLL_PIN variant of get_user_pages_locked().
3126 * Behavior is the same, except that this one sets FOLL_PIN and rejects
3129 long pin_user_pages_locked(unsigned long start
, unsigned long nr_pages
,
3130 unsigned int gup_flags
, struct page
**pages
,
3134 * FIXME: Current FOLL_LONGTERM behavior is incompatible with
3135 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
3136 * vmas. As there are no users of this flag in this call we simply
3137 * disallow this option for now.
3139 if (WARN_ON_ONCE(gup_flags
& FOLL_LONGTERM
))
3142 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
3143 if (WARN_ON_ONCE(gup_flags
& FOLL_GET
))
3146 gup_flags
|= FOLL_PIN
;
3147 return __get_user_pages_locked(current
->mm
, start
, nr_pages
,
3148 pages
, NULL
, locked
,
3149 gup_flags
| FOLL_TOUCH
);
3151 EXPORT_SYMBOL(pin_user_pages_locked
);