#include <linux/migrate.h>
#include <linux/mm_inline.h>
#include <linux/sched/mm.h>
+#include <linux/shmem_fs.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
struct page *page = *pages;
struct folio *folio = page_folio(page);
- if (!folio_test_anon(folio))
+ if (is_zero_page(page) ||
+ !folio_test_anon(folio))
continue;
if (!folio_test_large(folio) || folio_test_hugetlb(folio))
VM_BUG_ON_PAGE(!PageAnonExclusive(&folio->page), page);
* FOLL_GET: folio's refcount will be incremented by @refs.
*
* FOLL_PIN on large folios: folio's refcount will be incremented by
- * @refs, and its compound_pincount will be incremented by @refs.
+ * @refs, and its pincount will be incremented by @refs.
*
* FOLL_PIN on single-page folios: folio's refcount will be incremented by
* @refs * GUP_PIN_COUNTING_BIAS.
*/
struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags)
{
+ struct folio *folio;
+
+ if (WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == 0))
+ return NULL;
+
+ if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
+ return NULL;
+
if (flags & FOLL_GET)
return try_get_folio(page, refs);
- else if (flags & FOLL_PIN) {
- struct folio *folio;
- /*
- * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
- * right zone, so fail and let the caller fall back to the slow
- * path.
- */
- if (unlikely((flags & FOLL_LONGTERM) &&
- !is_longterm_pinnable_page(page)))
- return NULL;
+ /* FOLL_PIN is set */
- /*
- * CAUTION: Don't use compound_head() on the page before this
- * point, the result won't be stable.
- */
- folio = try_get_folio(page, refs);
- if (!folio)
- return NULL;
+ /*
+ * Don't take a pin on the zero page - it's not going anywhere
+ * and it is used in a *lot* of places.
+ */
+ if (is_zero_page(page))
+ return page_folio(page);
- /*
- * When pinning a large folio, use an exact count to track it.
- *
- * However, be sure to *also* increment the normal folio
- * refcount field at least once, so that the folio really
- * is pinned. That's why the refcount from the earlier
- * try_get_folio() is left intact.
- */
- if (folio_test_large(folio))
- atomic_add(refs, folio_pincount_ptr(folio));
- else
- folio_ref_add(folio,
- refs * (GUP_PIN_COUNTING_BIAS - 1));
- node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs);
+ folio = try_get_folio(page, refs);
+ if (!folio)
+ return NULL;
- return folio;
+ /*
+ * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
+ * right zone, so fail and let the caller fall back to the slow
+ * path.
+ */
+ if (unlikely((flags & FOLL_LONGTERM) &&
+ !folio_is_longterm_pinnable(folio))) {
+ if (!put_devmap_managed_page_refs(&folio->page, refs))
+ folio_put_refs(folio, refs);
+ return NULL;
}
- WARN_ON_ONCE(1);
- return NULL;
+ /*
+ * When pinning a large folio, use an exact count to track it.
+ *
+ * However, be sure to *also* increment the normal folio
+ * refcount field at least once, so that the folio really
+ * is pinned. That's why the refcount from the earlier
+ * try_get_folio() is left intact.
+ */
+ if (folio_test_large(folio))
+ atomic_add(refs, &folio->_pincount);
+ else
+ folio_ref_add(folio,
+ refs * (GUP_PIN_COUNTING_BIAS - 1));
+ /*
+ * Adjust the pincount before re-checking the PTE for changes.
+ * This is essentially a smp_mb() and is paired with a memory
+ * barrier in folio_try_share_anon_rmap_*().
+ */
+ smp_mb__after_atomic();
+
+ node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs);
+
+ return folio;
}
static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
{
if (flags & FOLL_PIN) {
+ if (is_zero_folio(folio))
+ return;
node_stat_mod_folio(folio, NR_FOLL_PIN_RELEASED, refs);
if (folio_test_large(folio))
- atomic_sub(refs, folio_pincount_ptr(folio));
+ atomic_sub(refs, &folio->_pincount);
else
refs *= GUP_PIN_COUNTING_BIAS;
}
* time. Cases: please see the try_grab_folio() documentation, with
* "refs=1".
*
- * Return: true for success, or if no action was required (if neither FOLL_PIN
- * nor FOLL_GET was set, nothing is done). False for failure: FOLL_GET or
- * FOLL_PIN was set, but the page could not be grabbed.
+ * Return: 0 for success, or if no action was required (if neither FOLL_PIN
+ * nor FOLL_GET was set, nothing is done). A negative error code for failure:
+ *
+ * -ENOMEM FOLL_GET or FOLL_PIN was set, but the page could not
+ * be grabbed.
*/
-bool __must_check try_grab_page(struct page *page, unsigned int flags)
+int __must_check try_grab_page(struct page *page, unsigned int flags)
{
struct folio *folio = page_folio(page);
- WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN));
if (WARN_ON_ONCE(folio_ref_count(folio) <= 0))
- return false;
+ return -ENOMEM;
+
+ if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
+ return -EREMOTEIO;
if (flags & FOLL_GET)
folio_ref_inc(folio);
else if (flags & FOLL_PIN) {
+ /*
+ * Don't take a pin on the zero page - it's not going anywhere
+ * and it is used in a *lot* of places.
+ */
+ if (is_zero_page(page))
+ return 0;
+
/*
* Similar to try_grab_folio(): be sure to *also*
* increment the normal page refcount field at least once,
*/
if (folio_test_large(folio)) {
folio_ref_add(folio, 1);
- atomic_add(1, folio_pincount_ptr(folio));
+ atomic_add(1, &folio->_pincount);
} else {
folio_ref_add(folio, GUP_PIN_COUNTING_BIAS);
}
node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1);
}
- return true;
+ return 0;
}
/**
}
EXPORT_SYMBOL(unpin_user_page);
+/**
+ * folio_add_pin - Try to get an additional pin on a pinned folio
+ * @folio: The folio to be pinned
+ *
+ * Get an additional pin on a folio we already have a pin on. Makes no change
+ * if the folio is a zero_page.
+ */
+void folio_add_pin(struct folio *folio)
+{
+ if (is_zero_folio(folio))
+ return;
+
+ /*
+ * Similar to try_grab_folio(): be sure to *also* increment the normal
+ * page refcount field at least once, so that the page really is
+ * pinned.
+ */
+ if (folio_test_large(folio)) {
+ WARN_ON_ONCE(atomic_read(&folio->_pincount) < 1);
+ folio_ref_inc(folio);
+ atomic_inc(&folio->_pincount);
+ } else {
+ WARN_ON_ONCE(folio_ref_count(folio) < GUP_PIN_COUNTING_BIAS);
+ folio_ref_add(folio, GUP_PIN_COUNTING_BIAS);
+ }
+}
+
static inline struct folio *gup_folio_range_next(struct page *start,
unsigned long npages, unsigned long i, unsigned int *ntails)
{
pte_t *pte, unsigned int flags)
{
if (flags & FOLL_TOUCH) {
- pte_t entry = *pte;
+ pte_t orig_entry = ptep_get(pte);
+ pte_t entry = orig_entry;
if (flags & FOLL_WRITE)
entry = pte_mkdirty(entry);
entry = pte_mkyoung(entry);
- if (!pte_same(*pte, entry)) {
+ if (!pte_same(orig_entry, entry)) {
set_pte_at(vma->vm_mm, address, pte, entry);
update_mmu_cache(vma, address, pte);
}
return -EEXIST;
}
-/*
- * FOLL_FORCE can write to even unwritable pte's, but only
- * after we've gone through a COW cycle and they are dirty.
- */
-static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
+/* FOLL_FORCE can write to even unwritable PTEs in COW mappings. */
+static inline bool can_follow_write_pte(pte_t pte, struct page *page,
+ struct vm_area_struct *vma,
+ unsigned int flags)
{
- return pte_write(pte) ||
- ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
+ /* If the pte is writable, we can write to the page. */
+ if (pte_write(pte))
+ return true;
+
+ /* Maybe FOLL_FORCE is set to override it? */
+ if (!(flags & FOLL_FORCE))
+ return false;
+
+ /* But FOLL_FORCE has no effect on shared mappings */
+ if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
+ return false;
+
+ /* ... or read-only private ones */
+ if (!(vma->vm_flags & VM_MAYWRITE))
+ return false;
+
+ /* ... or already writable ones that just need to take a write fault */
+ if (vma->vm_flags & VM_WRITE)
+ return false;
+
+ /*
+ * See can_change_pte_writable(): we broke COW and could map the page
+ * writable if we have an exclusive anonymous page ...
+ */
+ if (!page || !PageAnon(page) || !PageAnonExclusive(page))
+ return false;
+
+ /* ... and a write-fault isn't required for other reasons. */
+ if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
+ return false;
+ return !userfaultfd_pte_wp(vma, pte);
}
static struct page *follow_page_pte(struct vm_area_struct *vma,
if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
(FOLL_PIN | FOLL_GET)))
return ERR_PTR(-EINVAL);
-retry:
- if (unlikely(pmd_bad(*pmd)))
- return no_page_table(vma, flags);
ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
- pte = *ptep;
- if (!pte_present(pte)) {
- swp_entry_t entry;
- /*
- * KSM's break_ksm() relies upon recognizing a ksm page
- * even while it is being migrated, so for that case we
- * need migration_entry_wait().
- */
- if (likely(!(flags & FOLL_MIGRATION)))
- goto no_page;
- if (pte_none(pte))
- goto no_page;
- entry = pte_to_swp_entry(pte);
- if (!is_migration_entry(entry))
- goto no_page;
- pte_unmap_unlock(ptep, ptl);
- migration_entry_wait(mm, pmd, address);
- goto retry;
- }
- if ((flags & FOLL_NUMA) && pte_protnone(pte))
+ if (!ptep)
+ return no_page_table(vma, flags);
+ pte = ptep_get(ptep);
+ if (!pte_present(pte))
+ goto no_page;
+ if (pte_protnone(pte) && !gup_can_follow_protnone(vma, flags))
goto no_page;
- if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) {
- pte_unmap_unlock(ptep, ptl);
- return NULL;
- }
page = vm_normal_page(vma, address, pte);
+
+ /*
+ * We only care about anon pages in can_follow_write_pte() and don't
+ * have to worry about pte_devmap() because they are never anon.
+ */
+ if ((flags & FOLL_WRITE) &&
+ !can_follow_write_pte(pte, page, vma, flags)) {
+ page = NULL;
+ goto out;
+ }
+
if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
/*
* Only return device mapping pages in the FOLL_GET or FOLL_PIN
}
}
- if (!pte_write(pte) && gup_must_unshare(flags, page)) {
+ if (!pte_write(pte) && gup_must_unshare(vma, flags, page)) {
page = ERR_PTR(-EMLINK);
goto out;
}
!PageAnonExclusive(page), page);
/* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */
- if (unlikely(!try_grab_page(page, flags))) {
- page = ERR_PTR(-ENOMEM);
+ ret = try_grab_page(page, flags);
+ if (unlikely(ret)) {
+ page = ERR_PTR(ret);
goto out;
}
+
/*
* We need to make the page accessible if and only if we are going
* to access its content (the FOLL_PIN case). Please see
struct mm_struct *mm = vma->vm_mm;
pmd = pmd_offset(pudp, address);
- /*
- * The READ_ONCE() will stabilize the pmdval in a register or
- * on the stack so that it will stop changing under the code.
- */
- pmdval = READ_ONCE(*pmd);
+ pmdval = pmdp_get_lockless(pmd);
if (pmd_none(pmdval))
return no_page_table(vma, flags);
- if (pmd_huge(pmdval) && is_vm_hugetlb_page(vma)) {
- page = follow_huge_pmd(mm, address, pmd, flags);
- if (page)
- return page;
- return no_page_table(vma, flags);
- }
- if (is_hugepd(__hugepd(pmd_val(pmdval)))) {
- page = follow_huge_pd(vma, address,
- __hugepd(pmd_val(pmdval)), flags,
- PMD_SHIFT);
- if (page)
- return page;
+ if (!pmd_present(pmdval))
return no_page_table(vma, flags);
- }
-retry:
- if (!pmd_present(pmdval)) {
- /*
- * Should never reach here, if thp migration is not supported;
- * Otherwise, it must be a thp migration entry.
- */
- VM_BUG_ON(!thp_migration_supported() ||
- !is_pmd_migration_entry(pmdval));
-
- if (likely(!(flags & FOLL_MIGRATION)))
- return no_page_table(vma, flags);
-
- pmd_migration_entry_wait(mm, pmd);
- pmdval = READ_ONCE(*pmd);
- /*
- * MADV_DONTNEED may convert the pmd to null because
- * mmap_lock is held in read mode
- */
- if (pmd_none(pmdval))
- return no_page_table(vma, flags);
- goto retry;
- }
if (pmd_devmap(pmdval)) {
ptl = pmd_lock(mm, pmd);
page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);
spin_unlock(ptl);
if (page)
return page;
+ return no_page_table(vma, flags);
}
if (likely(!pmd_trans_huge(pmdval)))
return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
- if ((flags & FOLL_NUMA) && pmd_protnone(pmdval))
+ if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags))
return no_page_table(vma, flags);
-retry_locked:
ptl = pmd_lock(mm, pmd);
- if (unlikely(pmd_none(*pmd))) {
- spin_unlock(ptl);
- return no_page_table(vma, flags);
- }
if (unlikely(!pmd_present(*pmd))) {
spin_unlock(ptl);
- if (likely(!(flags & FOLL_MIGRATION)))
- return no_page_table(vma, flags);
- pmd_migration_entry_wait(mm, pmd);
- goto retry_locked;
+ return no_page_table(vma, flags);
}
if (unlikely(!pmd_trans_huge(*pmd))) {
spin_unlock(ptl);
return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
}
if (flags & FOLL_SPLIT_PMD) {
- int ret;
- page = pmd_page(*pmd);
- if (is_huge_zero_page(page)) {
- spin_unlock(ptl);
- ret = 0;
- split_huge_pmd(vma, pmd, address);
- if (pmd_trans_unstable(pmd))
- ret = -EBUSY;
- } else {
- spin_unlock(ptl);
- split_huge_pmd(vma, pmd, address);
- ret = pte_alloc(mm, pmd) ? -ENOMEM : 0;
- }
-
- return ret ? ERR_PTR(ret) :
+ spin_unlock(ptl);
+ split_huge_pmd(vma, pmd, address);
+ /* If pmd was left empty, stuff a page table in there quickly */
+ return pte_alloc(mm, pmd) ? ERR_PTR(-ENOMEM) :
follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
}
page = follow_trans_huge_pmd(vma, address, pmd, flags);
pud = pud_offset(p4dp, address);
if (pud_none(*pud))
return no_page_table(vma, flags);
- if (pud_huge(*pud) && is_vm_hugetlb_page(vma)) {
- page = follow_huge_pud(mm, address, pud, flags);
- if (page)
- return page;
- return no_page_table(vma, flags);
- }
- if (is_hugepd(__hugepd(pud_val(*pud)))) {
- page = follow_huge_pd(vma, address,
- __hugepd(pud_val(*pud)), flags,
- PUD_SHIFT);
- if (page)
- return page;
- return no_page_table(vma, flags);
- }
if (pud_devmap(*pud)) {
ptl = pud_lock(mm, pud);
page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap);
spin_unlock(ptl);
if (page)
return page;
+ return no_page_table(vma, flags);
}
if (unlikely(pud_bad(*pud)))
return no_page_table(vma, flags);
struct follow_page_context *ctx)
{
p4d_t *p4d;
- struct page *page;
p4d = p4d_offset(pgdp, address);
if (p4d_none(*p4d))
if (unlikely(p4d_bad(*p4d)))
return no_page_table(vma, flags);
- if (is_hugepd(__hugepd(p4d_val(*p4d)))) {
- page = follow_huge_pd(vma, address,
- __hugepd(p4d_val(*p4d)), flags,
- P4D_SHIFT);
- if (page)
- return page;
- return no_page_table(vma, flags);
- }
return follow_pud_mask(vma, address, p4d, flags, ctx);
}
struct follow_page_context *ctx)
{
pgd_t *pgd;
- struct page *page;
struct mm_struct *mm = vma->vm_mm;
ctx->page_mask = 0;
- /* make this handle hugepd */
- page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
- if (!IS_ERR(page)) {
- WARN_ON_ONCE(flags & (FOLL_GET | FOLL_PIN));
- return page;
- }
+ /*
+ * Call hugetlb_follow_page_mask for hugetlb vmas as it will use
+ * special hugetlb page table walking code. This eliminates the
+ * need to check for hugetlb entries in the general walking code.
+ */
+ if (is_vm_hugetlb_page(vma))
+ return hugetlb_follow_page_mask(vma, address, flags,
+ &ctx->page_mask);
pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
return no_page_table(vma, flags);
- if (pgd_huge(*pgd)) {
- page = follow_huge_pgd(mm, address, pgd, flags);
- if (page)
- return page;
- return no_page_table(vma, flags);
- }
- if (is_hugepd(__hugepd(pgd_val(*pgd)))) {
- page = follow_huge_pd(vma, address,
- __hugepd(pgd_val(*pgd)), flags,
- PGDIR_SHIFT);
- if (page)
- return page;
- return no_page_table(vma, flags);
- }
-
return follow_p4d_mask(vma, address, pgd, flags, ctx);
}
if (vma_is_secretmem(vma))
return NULL;
- if (foll_flags & FOLL_PIN)
+ if (WARN_ON_ONCE(foll_flags & FOLL_PIN))
return NULL;
+ /*
+ * We never set FOLL_HONOR_NUMA_FAULT because callers don't expect
+ * to fail on PROT_NONE-mapped pages.
+ */
page = follow_page_mask(vma, address, foll_flags, &ctx);
if (ctx.pgmap)
put_dev_pagemap(ctx.pgmap);
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
+ pte_t entry;
int ret = -EFAULT;
/* user gate pages are read-only */
pmd = pmd_offset(pud, address);
if (!pmd_present(*pmd))
return -EFAULT;
- VM_BUG_ON(pmd_trans_huge(*pmd));
pte = pte_offset_map(pmd, address);
- if (pte_none(*pte))
+ if (!pte)
+ return -EFAULT;
+ entry = ptep_get(pte);
+ if (pte_none(entry))
goto unmap;
*vma = get_gate_vma(mm);
if (!page)
goto out;
- *page = vm_normal_page(*vma, address, *pte);
+ *page = vm_normal_page(*vma, address, entry);
if (!*page) {
- if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(*pte)))
+ if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(entry)))
goto unmap;
- *page = pte_page(*pte);
+ *page = pte_page(entry);
}
- if (unlikely(!try_grab_page(*page, gup_flags))) {
- ret = -ENOMEM;
+ ret = try_grab_page(*page, gup_flags);
+ if (unlikely(ret))
goto unmap;
- }
out:
ret = 0;
unmap:
}
/*
- * mmap_lock must be held on entry. If @locked != NULL and *@flags
- * does not include FOLL_NOWAIT, the mmap_lock may be released. If it
- * is, *@locked will be set to 0 and -EBUSY returned.
+ * mmap_lock must be held on entry. If @flags has FOLL_UNLOCKABLE but not
+ * FOLL_NOWAIT, the mmap_lock may be released. If it is, *@locked will be set
+ * to 0 and -EBUSY returned.
*/
static int faultin_page(struct vm_area_struct *vma,
unsigned long address, unsigned int *flags, bool unshare,
fault_flags |= FAULT_FLAG_WRITE;
if (*flags & FOLL_REMOTE)
fault_flags |= FAULT_FLAG_REMOTE;
- if (locked)
+ if (*flags & FOLL_UNLOCKABLE) {
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ /*
+ * FAULT_FLAG_INTERRUPTIBLE is opt-in. GUP callers must set
+ * FOLL_INTERRUPTIBLE to enable FAULT_FLAG_INTERRUPTIBLE.
+ * That's because some callers may not be prepared to
+ * handle early exits caused by non-fatal signals.
+ */
+ if (*flags & FOLL_INTERRUPTIBLE)
+ fault_flags |= FAULT_FLAG_INTERRUPTIBLE;
+ }
if (*flags & FOLL_NOWAIT)
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
if (*flags & FOLL_TRIED) {
* mmap lock in the page fault handler. Sanity check this.
*/
WARN_ON_ONCE(fault_flags & FAULT_FLAG_RETRY_NOWAIT);
- if (locked)
- *locked = 0;
+ *locked = 0;
+
/*
* We should do the same as VM_FAULT_RETRY, but let's not
* return -EBUSY since that's not reflecting the reality of
}
if (ret & VM_FAULT_RETRY) {
- if (locked && !(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
+ if (!(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
*locked = 0;
return -EBUSY;
}
+ return 0;
+}
+
+/*
+ * Writing to file-backed mappings which require folio dirty tracking using GUP
+ * is a fundamentally broken operation, as kernel write access to GUP mappings
+ * do not adhere to the semantics expected by a file system.
+ *
+ * Consider the following scenario:-
+ *
+ * 1. A folio is written to via GUP which write-faults the memory, notifying
+ * the file system and dirtying the folio.
+ * 2. Later, writeback is triggered, resulting in the folio being cleaned and
+ * the PTE being marked read-only.
+ * 3. The GUP caller writes to the folio, as it is mapped read/write via the
+ * direct mapping.
+ * 4. The GUP caller, now done with the page, unpins it and sets it dirty
+ * (though it does not have to).
+ *
+ * This results in both data being written to a folio without writenotify, and
+ * the folio being dirtied unexpectedly (if the caller decides to do so).
+ */
+static bool writable_file_mapping_allowed(struct vm_area_struct *vma,
+ unsigned long gup_flags)
+{
+ /*
+ * If we aren't pinning then no problematic write can occur. A long term
+ * pin is the most egregious case so this is the case we disallow.
+ */
+ if ((gup_flags & (FOLL_PIN | FOLL_LONGTERM)) !=
+ (FOLL_PIN | FOLL_LONGTERM))
+ return true;
+
/*
- * The VM_FAULT_WRITE bit tells us that do_wp_page has broken COW when
- * necessary, even if maybe_mkwrite decided not to set pte_write. We
- * can thus safely do subsequent page lookups as if they were reads.
- * But only do so when looping for pte_write is futile: in some cases
- * userspace may also be wanting to write to the gotten user page,
- * which a read fault here might prevent (a readonly page might get
- * reCOWed by userspace write).
+ * If the VMA does not require dirty tracking then no problematic write
+ * can occur either.
*/
- if ((ret & VM_FAULT_WRITE) && !(vma->vm_flags & VM_WRITE))
- *flags |= FOLL_COW;
- return 0;
+ return !vma_needs_dirty_tracking(vma);
}
static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
vm_flags_t vm_flags = vma->vm_flags;
int write = (gup_flags & FOLL_WRITE);
int foreign = (gup_flags & FOLL_REMOTE);
+ bool vma_anon = vma_is_anonymous(vma);
if (vm_flags & (VM_IO | VM_PFNMAP))
return -EFAULT;
- if (gup_flags & FOLL_ANON && !vma_is_anonymous(vma))
+ if ((gup_flags & FOLL_ANON) && !vma_anon)
return -EFAULT;
if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma))
return -EFAULT;
if (write) {
- if (!(vm_flags & VM_WRITE)) {
+ if (!vma_anon &&
+ !writable_file_mapping_allowed(vma, gup_flags))
+ return -EFAULT;
+
+ if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) {
if (!(gup_flags & FOLL_FORCE))
return -EFAULT;
+ /* hugetlb does not support FOLL_FORCE|FOLL_WRITE. */
+ if (is_vm_hugetlb_page(vma))
+ return -EFAULT;
/*
* We used to let the write,force case do COW in a
* VM_MAYWRITE VM_SHARED !VM_WRITE vma, so ptrace could
return 0;
}
+/*
+ * This is "vma_lookup()", but with a warning if we would have
+ * historically expanded the stack in the GUP code.
+ */
+static struct vm_area_struct *gup_vma_lookup(struct mm_struct *mm,
+ unsigned long addr)
+{
+#ifdef CONFIG_STACK_GROWSUP
+ return vma_lookup(mm, addr);
+#else
+ static volatile unsigned long next_warn;
+ struct vm_area_struct *vma;
+ unsigned long now, next;
+
+ vma = find_vma(mm, addr);
+ if (!vma || (addr >= vma->vm_start))
+ return vma;
+
+ /* Only warn for half-way relevant accesses */
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ return NULL;
+ if (vma->vm_start - addr > 65536)
+ return NULL;
+
+ /* Let's not warn more than once an hour.. */
+ now = jiffies; next = next_warn;
+ if (next && time_before(now, next))
+ return NULL;
+ next_warn = now + 60*60*HZ;
+
+ /* Let people know things may have changed. */
+ pr_warn("GUP no longer grows the stack in %s (%d): %lx-%lx (%lx)\n",
+ current->comm, task_pid_nr(current),
+ vma->vm_start, vma->vm_end, addr);
+ dump_stack();
+ return NULL;
+#endif
+}
+
/**
* __get_user_pages() - pin user pages in memory
* @mm: mm_struct of target mm
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long. Or NULL, if caller
* only intends to ensure the pages are faulted in.
- * @vmas: array of pointers to vmas corresponding to each page.
- * Or NULL if the caller does not require them.
* @locked: whether we're still with the mmap_lock held
*
* Returns either number of pages pinned (which may be less than the
*
* The caller is responsible for releasing returned @pages, via put_page().
*
- * @vmas are valid only as long as mmap_lock is held.
- *
* Must be called with mmap_lock held. It may be released. See below.
*
* __get_user_pages walks a process's page tables and takes a reference to
* This does not guarantee that the page exists in the user mappings when
* __get_user_pages returns, and there may even be a completely different
* page there in some cases (eg. if mmapped pagecache has been invalidated
- * and subsequently re faulted). However it does guarantee that the page
+ * and subsequently re-faulted). However it does guarantee that the page
* won't be freed completely. And mostly callers simply care that the page
* contains data that was valid *at some point in time*. Typically, an IO
* or similar operation cannot guarantee anything stronger anyway because
* appropriate) must be called after the page is finished with, and
* before put_page is called.
*
- * If @locked != NULL, *@locked will be set to 0 when mmap_lock is
- * released by an up_read(). That can happen if @gup_flags does not
- * have FOLL_NOWAIT.
+ * If FOLL_UNLOCKABLE is set without FOLL_NOWAIT then the mmap_lock may
+ * be released. If this happens *@locked will be set to 0 on return.
*
- * A caller using such a combination of @locked and @gup_flags
- * must therefore hold the mmap_lock for reading only, and recognize
- * when it's been released. Otherwise, it must be held for either
- * reading or writing and will not be released.
+ * A caller using such a combination of @gup_flags must therefore hold the
+ * mmap_lock for reading only, and recognize when it's been released. Otherwise,
+ * it must be held for either reading or writing and will not be released.
*
* In most cases, get_user_pages or get_user_pages_fast should be used
* instead of __get_user_pages. __get_user_pages should be used only if
static long __get_user_pages(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
+ int *locked)
{
long ret = 0, i = 0;
struct vm_area_struct *vma = NULL;
if (!nr_pages)
return 0;
- start = untagged_addr(start);
+ start = untagged_addr_remote(mm, start);
VM_BUG_ON(!!pages != !!(gup_flags & (FOLL_GET | FOLL_PIN)));
- /*
- * If FOLL_FORCE is set then do not force a full fault as the hinting
- * fault information is unrelated to the reference behaviour of a task
- * using the address space
- */
- if (!(gup_flags & FOLL_FORCE))
- gup_flags |= FOLL_NUMA;
-
do {
struct page *page;
unsigned int foll_flags = gup_flags;
/* first iteration or cross vma bound */
if (!vma || start >= vma->vm_end) {
- vma = find_extend_vma(mm, start);
+ vma = gup_vma_lookup(mm, start);
if (!vma && in_gate_area(mm, start)) {
ret = get_gate_page(mm, start & PAGE_MASK,
gup_flags, &vma,
- pages ? &pages[i] : NULL);
+ pages ? &page : NULL);
if (ret)
goto out;
ctx.page_mask = 0;
ret = check_vma_flags(vma, gup_flags);
if (ret)
goto out;
-
- if (is_vm_hugetlb_page(vma)) {
- i = follow_hugetlb_page(mm, vma, pages, vmas,
- &start, &nr_pages, i,
- gup_flags, locked);
- if (locked && *locked == 0) {
- /*
- * We've got a VM_FAULT_RETRY
- * and we've lost mmap_lock.
- * We must stop here.
- */
- BUG_ON(gup_flags & FOLL_NOWAIT);
- goto out;
- }
- continue;
- }
}
retry:
/*
ret = PTR_ERR(page);
goto out;
}
-
- goto next_page;
} else if (IS_ERR(page)) {
ret = PTR_ERR(page);
goto out;
}
- if (pages) {
- pages[i] = page;
- flush_anon_page(vma, page, start);
- flush_dcache_page(page);
- ctx.page_mask = 0;
- }
next_page:
- if (vmas) {
- vmas[i] = vma;
- ctx.page_mask = 0;
- }
page_increm = 1 + (~(start >> PAGE_SHIFT) & ctx.page_mask);
if (page_increm > nr_pages)
page_increm = nr_pages;
+
+ if (pages) {
+ struct page *subpage;
+ unsigned int j;
+
+ /*
+ * This must be a large folio (and doesn't need to
+ * be the whole folio; it can be part of it), do
+ * the refcount work for all the subpages too.
+ *
+ * NOTE: here the page may not be the head page
+ * e.g. when start addr is not thp-size aligned.
+ * try_grab_folio() should have taken care of tail
+ * pages.
+ */
+ if (page_increm > 1) {
+ struct folio *folio;
+
+ /*
+ * Since we already hold refcount on the
+ * large folio, this should never fail.
+ */
+ folio = try_grab_folio(page, page_increm - 1,
+ foll_flags);
+ if (WARN_ON_ONCE(!folio)) {
+ /*
+ * Release the 1st page ref if the
+ * folio is problematic, fail hard.
+ */
+ gup_put_folio(page_folio(page), 1,
+ foll_flags);
+ ret = -EFAULT;
+ goto out;
+ }
+ }
+
+ for (j = 0; j < page_increm; j++) {
+ subpage = nth_page(page, j);
+ pages[i + j] = subpage;
+ flush_anon_page(vma, subpage, start + j * PAGE_SIZE);
+ flush_dcache_page(subpage);
+ }
+ }
+
i += page_increm;
start += page_increm * PAGE_SIZE;
nr_pages -= page_increm;
struct vm_area_struct *vma;
vm_fault_t ret;
- address = untagged_addr(address);
+ address = untagged_addr_remote(mm, address);
if (unlocked)
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
retry:
- vma = find_extend_vma(mm, address);
- if (!vma || address < vma->vm_start)
+ vma = gup_vma_lookup(mm, address);
+ if (!vma)
return -EFAULT;
if (!vma_permits_fault(vma, fault_flags))
EXPORT_SYMBOL_GPL(fixup_user_fault);
/*
- * Please note that this function, unlike __get_user_pages will not
- * return 0 for nr_pages > 0 without FOLL_NOWAIT
+ * GUP always responds to fatal signals. When FOLL_INTERRUPTIBLE is
+ * specified, it'll also respond to generic signals. The caller of GUP
+ * that has FOLL_INTERRUPTIBLE should take care of the GUP interruption.
+ */
+static bool gup_signal_pending(unsigned int flags)
+{
+ if (fatal_signal_pending(current))
+ return true;
+
+ if (!(flags & FOLL_INTERRUPTIBLE))
+ return false;
+
+ return signal_pending(current);
+}
+
+/*
+ * Locking: (*locked == 1) means that the mmap_lock has already been acquired by
+ * the caller. This function may drop the mmap_lock. If it does so, then it will
+ * set (*locked = 0).
+ *
+ * (*locked == 0) means that the caller expects this function to acquire and
+ * drop the mmap_lock. Therefore, the value of *locked will still be zero when
+ * the function returns, even though it may have changed temporarily during
+ * function execution.
+ *
+ * Please note that this function, unlike __get_user_pages(), will not return 0
+ * for nr_pages > 0, unless FOLL_NOWAIT is used.
*/
static __always_inline long __get_user_pages_locked(struct mm_struct *mm,
unsigned long start,
unsigned long nr_pages,
struct page **pages,
- struct vm_area_struct **vmas,
int *locked,
unsigned int flags)
{
long ret, pages_done;
- bool lock_dropped;
+ bool must_unlock = false;
- if (locked) {
- /* if VM_FAULT_RETRY can be returned, vmas become invalid */
- BUG_ON(vmas);
- /* check caller initialized locked */
- BUG_ON(*locked != 1);
+ if (!nr_pages)
+ return 0;
+
+ /*
+ * The internal caller expects GUP to manage the lock internally and the
+ * lock must be released when this returns.
+ */
+ if (!*locked) {
+ if (mmap_read_lock_killable(mm))
+ return -EAGAIN;
+ must_unlock = true;
+ *locked = 1;
}
+ else
+ mmap_assert_locked(mm);
if (flags & FOLL_PIN)
mm_set_has_pinned_flag(&mm->flags);
flags |= FOLL_GET;
pages_done = 0;
- lock_dropped = false;
for (;;) {
ret = __get_user_pages(mm, start, nr_pages, flags, pages,
- vmas, locked);
- if (!locked)
+ locked);
+ if (!(flags & FOLL_UNLOCKABLE)) {
/* VM_FAULT_RETRY couldn't trigger, bypass */
- return ret;
+ pages_done = ret;
+ break;
+ }
/* VM_FAULT_RETRY or VM_FAULT_COMPLETED cannot return errors */
if (!*locked) {
if (likely(pages))
pages += ret;
start += ret << PAGE_SHIFT;
- lock_dropped = true;
+
+ /* The lock was temporarily dropped, so we must unlock later */
+ must_unlock = true;
retry:
/*
* Repeat on the address that fired VM_FAULT_RETRY
* with both FAULT_FLAG_ALLOW_RETRY and
* FAULT_FLAG_TRIED. Note that GUP can be interrupted
- * by fatal signals, so we need to check it before we
+ * by fatal signals of even common signals, depending on
+ * the caller's request. So we need to check it before we
* start trying again otherwise it can loop forever.
*/
-
- if (fatal_signal_pending(current)) {
+ if (gup_signal_pending(flags)) {
if (!pages_done)
pages_done = -EINTR;
break;
*locked = 1;
ret = __get_user_pages(mm, start, 1, flags | FOLL_TRIED,
- pages, NULL, locked);
+ pages, locked);
if (!*locked) {
/* Continue to retry until we succeeded */
BUG_ON(ret != 0);
pages++;
start += PAGE_SIZE;
}
- if (lock_dropped && *locked) {
+ if (must_unlock && *locked) {
/*
- * We must let the caller know we temporarily dropped the lock
- * and so the critical section protected by it was lost.
+ * We either temporarily dropped the lock, or the caller
+ * requested that we both acquire and drop the lock. Either way,
+ * we must now unlock, and notify the caller of that state.
*/
mmap_read_unlock(mm);
*locked = 0;
}
+
+ /*
+ * Failing to pin anything implies something has gone wrong (except when
+ * FOLL_NOWAIT is specified).
+ */
+ if (WARN_ON_ONCE(pages_done == 0 && !(flags & FOLL_NOWAIT)))
+ return -EFAULT;
+
return pages_done;
}
{
struct mm_struct *mm = vma->vm_mm;
unsigned long nr_pages = (end - start) / PAGE_SIZE;
+ int local_locked = 1;
int gup_flags;
long ret;
if (vma_is_accessible(vma))
gup_flags |= FOLL_FORCE;
+ if (locked)
+ gup_flags |= FOLL_UNLOCKABLE;
+
/*
* We made sure addr is within a VMA, so the following will
* not result in a stack expansion that recurses back here.
*/
ret = __get_user_pages(mm, start, nr_pages, gup_flags,
- NULL, NULL, locked);
+ NULL, locked ? locked : &local_locked);
lru_add_drain();
return ret;
}
* code on error (see __get_user_pages()).
*
* vma->vm_mm->mmap_lock must be held. The range must be page-aligned and
- * covered by the VMA.
- *
- * If @locked is NULL, it may be held for read or write and will be unperturbed.
- *
- * If @locked is non-NULL, it must held for read only and may be released. If
- * it's released, *@locked will be set to 0.
+ * covered by the VMA. If it's released, *@locked will be set to 0.
*/
long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end, bool write, int *locked)
* a poisoned page.
* !FOLL_FORCE: Require proper access permissions.
*/
- gup_flags = FOLL_TOUCH | FOLL_HWPOISON;
+ gup_flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_UNLOCKABLE;
if (write)
gup_flags |= FOLL_WRITE;
return -EINVAL;
ret = __get_user_pages(mm, start, nr_pages, gup_flags,
- NULL, NULL, locked);
+ NULL, locked);
lru_add_drain();
return ret;
}
if (!locked) {
locked = 1;
mmap_read_lock(mm);
- vma = find_vma(mm, nstart);
+ vma = find_vma_intersection(mm, nstart, end);
} else if (nstart >= vma->vm_end)
- vma = vma->vm_next;
- if (!vma || vma->vm_start >= end)
+ vma = find_vma_intersection(mm, vma->vm_end, end);
+
+ if (!vma)
break;
/*
* Set [nstart; nend) to intersection of desired address
#else /* CONFIG_MMU */
static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
unsigned long nr_pages, struct page **pages,
- struct vm_area_struct **vmas, int *locked,
- unsigned int foll_flags)
+ int *locked, unsigned int foll_flags)
{
struct vm_area_struct *vma;
+ bool must_unlock = false;
unsigned long vm_flags;
long i;
+ if (!nr_pages)
+ return 0;
+
+ /*
+ * The internal caller expects GUP to manage the lock internally and the
+ * lock must be released when this returns.
+ */
+ if (!*locked) {
+ if (mmap_read_lock_killable(mm))
+ return -EAGAIN;
+ must_unlock = true;
+ *locked = 1;
+ }
+
/* calculate required read or write permissions.
* If FOLL_FORCE is set, we only require the "MAY" flags.
*/
for (i = 0; i < nr_pages; i++) {
vma = find_vma(mm, start);
if (!vma)
- goto finish_or_fault;
+ break;
/* protect what we can, including chardevs */
if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
!(vm_flags & vma->vm_flags))
- goto finish_or_fault;
+ break;
if (pages) {
pages[i] = virt_to_page((void *)start);
if (pages[i])
get_page(pages[i]);
}
- if (vmas)
- vmas[i] = vma;
+
start = (start + PAGE_SIZE) & PAGE_MASK;
}
- return i;
+ if (must_unlock && *locked) {
+ mmap_read_unlock(mm);
+ *locked = 0;
+ }
-finish_or_fault:
return i ? : -EFAULT;
}
#endif /* !CONFIG_MMU */
#ifdef CONFIG_ELF_CORE
struct page *get_dump_page(unsigned long addr)
{
- struct mm_struct *mm = current->mm;
struct page *page;
- int locked = 1;
+ int locked = 0;
int ret;
- if (mmap_read_lock_killable(mm))
- return NULL;
- ret = __get_user_pages_locked(mm, addr, 1, &page, NULL, &locked,
+ ret = __get_user_pages_locked(current->mm, addr, 1, &page, &locked,
FOLL_FORCE | FOLL_DUMP | FOLL_GET);
- if (locked)
- mmap_read_unlock(mm);
return (ret == 1) ? page : NULL;
}
#endif /* CONFIG_ELF_CORE */
#ifdef CONFIG_MIGRATION
/*
- * Check whether all pages are pinnable, if so return number of pages. If some
- * pages are not pinnable, migrate them, and unpin all pages. Return zero if
- * pages were migrated, or if some pages were not successfully isolated.
- * Return negative error if migration fails.
+ * Returns the number of collected pages. Return value is always >= 0.
*/
-static long check_and_migrate_movable_pages(unsigned long nr_pages,
- struct page **pages,
- unsigned int gup_flags)
+static unsigned long collect_longterm_unpinnable_pages(
+ struct list_head *movable_page_list,
+ unsigned long nr_pages,
+ struct page **pages)
{
- unsigned long isolation_error_count = 0, i;
+ unsigned long i, collected = 0;
struct folio *prev_folio = NULL;
- LIST_HEAD(movable_page_list);
- bool drain_allow = true, coherent_pages = false;
- int ret = 0;
+ bool drain_allow = true;
for (i = 0; i < nr_pages; i++) {
struct folio *folio = page_folio(pages[i]);
continue;
prev_folio = folio;
- /*
- * Device coherent pages are managed by a driver and should not
- * be pinned indefinitely as it prevents the driver moving the
- * page. So when trying to pin with FOLL_LONGTERM instead try
- * to migrate the page out of device memory.
- */
- if (folio_is_device_coherent(folio)) {
- /*
- * We always want a new GUP lookup with device coherent
- * pages.
- */
- pages[i] = 0;
- coherent_pages = true;
-
- /*
- * Migration will fail if the page is pinned, so convert
- * the pin on the source page to a normal reference.
- */
- if (gup_flags & FOLL_PIN) {
- get_page(&folio->page);
- unpin_user_page(&folio->page);
- }
+ if (folio_is_longterm_pinnable(folio))
+ continue;
- ret = migrate_device_coherent_page(&folio->page);
- if (ret)
- goto unpin_pages;
+ collected++;
+ if (folio_is_device_coherent(folio))
continue;
- }
- if (folio_is_longterm_pinnable(folio))
- continue;
- /*
- * Try to move out any movable page before pinning the range.
- */
if (folio_test_hugetlb(folio)) {
- if (isolate_hugetlb(&folio->page,
- &movable_page_list))
- isolation_error_count++;
+ isolate_hugetlb(folio, movable_page_list);
continue;
}
drain_allow = false;
}
- if (folio_isolate_lru(folio)) {
- isolation_error_count++;
+ if (!folio_isolate_lru(folio))
continue;
- }
- list_add_tail(&folio->lru, &movable_page_list);
+
+ list_add_tail(&folio->lru, movable_page_list);
node_stat_mod_folio(folio,
NR_ISOLATED_ANON + folio_is_file_lru(folio),
folio_nr_pages(folio));
}
- if (!list_empty(&movable_page_list) || isolation_error_count ||
- coherent_pages)
- goto unpin_pages;
+ return collected;
+}
- /*
- * If list is empty, and no isolation errors, means that all pages are
- * in the correct zone.
- */
- return nr_pages;
+/*
+ * Unpins all pages and migrates device coherent pages and movable_page_list.
+ * Returns -EAGAIN if all pages were successfully migrated or -errno for failure
+ * (or partial success).
+ */
+static int migrate_longterm_unpinnable_pages(
+ struct list_head *movable_page_list,
+ unsigned long nr_pages,
+ struct page **pages)
+{
+ int ret;
+ unsigned long i;
-unpin_pages:
- /*
- * pages[i] might be NULL if any device coherent pages were found.
- */
for (i = 0; i < nr_pages; i++) {
- if (!pages[i])
+ struct folio *folio = page_folio(pages[i]);
+
+ if (folio_is_device_coherent(folio)) {
+ /*
+ * Migration will fail if the page is pinned, so convert
+ * the pin on the source page to a normal reference.
+ */
+ pages[i] = NULL;
+ folio_get(folio);
+ gup_put_folio(folio, 1, FOLL_PIN);
+
+ if (migrate_device_coherent_page(&folio->page)) {
+ ret = -EBUSY;
+ goto err;
+ }
+
continue;
+ }
- if (gup_flags & FOLL_PIN)
- unpin_user_page(pages[i]);
- else
- put_page(pages[i]);
+ /*
+ * We can't migrate pages with unexpected references, so drop
+ * the reference obtained by __get_user_pages_locked().
+ * Migrating pages have been added to movable_page_list after
+ * calling folio_isolate_lru() which takes a reference so the
+ * page won't be freed if it's migrating.
+ */
+ unpin_user_page(pages[i]);
+ pages[i] = NULL;
}
- if (!list_empty(&movable_page_list)) {
+ if (!list_empty(movable_page_list)) {
struct migration_target_control mtc = {
.nid = NUMA_NO_NODE,
.gfp_mask = GFP_USER | __GFP_NOWARN,
};
- ret = migrate_pages(&movable_page_list, alloc_migration_target,
- NULL, (unsigned long)&mtc, MIGRATE_SYNC,
- MR_LONGTERM_PIN, NULL);
- if (ret > 0) /* number of pages not migrated */
+ if (migrate_pages(movable_page_list, alloc_migration_target,
+ NULL, (unsigned long)&mtc, MIGRATE_SYNC,
+ MR_LONGTERM_PIN, NULL)) {
ret = -ENOMEM;
+ goto err;
+ }
}
- if (ret && !list_empty(&movable_page_list))
- putback_movable_pages(&movable_page_list);
+ putback_movable_pages(movable_page_list);
+
+ return -EAGAIN;
+
+err:
+ for (i = 0; i < nr_pages; i++)
+ if (pages[i])
+ unpin_user_page(pages[i]);
+ putback_movable_pages(movable_page_list);
+
return ret;
}
+
+/*
+ * Check whether all pages are *allowed* to be pinned. Rather confusingly, all
+ * pages in the range are required to be pinned via FOLL_PIN, before calling
+ * this routine.
+ *
+ * If any pages in the range are not allowed to be pinned, then this routine
+ * will migrate those pages away, unpin all the pages in the range and return
+ * -EAGAIN. The caller should re-pin the entire range with FOLL_PIN and then
+ * call this routine again.
+ *
+ * If an error other than -EAGAIN occurs, this indicates a migration failure.
+ * The caller should give up, and propagate the error back up the call stack.
+ *
+ * If everything is OK and all pages in the range are allowed to be pinned, then
+ * this routine leaves all pages pinned and returns zero for success.
+ */
+static long check_and_migrate_movable_pages(unsigned long nr_pages,
+ struct page **pages)
+{
+ unsigned long collected;
+ LIST_HEAD(movable_page_list);
+
+ collected = collect_longterm_unpinnable_pages(&movable_page_list,
+ nr_pages, pages);
+ if (!collected)
+ return 0;
+
+ return migrate_longterm_unpinnable_pages(&movable_page_list, nr_pages,
+ pages);
+}
#else
static long check_and_migrate_movable_pages(unsigned long nr_pages,
- struct page **pages,
- unsigned int gup_flags)
+ struct page **pages)
{
- return nr_pages;
+ return 0;
}
#endif /* CONFIG_MIGRATION */
unsigned long start,
unsigned long nr_pages,
struct page **pages,
- struct vm_area_struct **vmas,
+ int *locked,
unsigned int gup_flags)
{
unsigned int flags;
- long rc;
+ long rc, nr_pinned_pages;
if (!(gup_flags & FOLL_LONGTERM))
- return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
- NULL, gup_flags);
+ return __get_user_pages_locked(mm, start, nr_pages, pages,
+ locked, gup_flags);
+
flags = memalloc_pin_save();
do {
- rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
- NULL, gup_flags);
- if (rc <= 0)
+ nr_pinned_pages = __get_user_pages_locked(mm, start, nr_pages,
+ pages, locked,
+ gup_flags);
+ if (nr_pinned_pages <= 0) {
+ rc = nr_pinned_pages;
break;
- rc = check_and_migrate_movable_pages(rc, pages, gup_flags);
- } while (!rc);
- memalloc_pin_restore(flags);
+ }
- return rc;
+ /* FOLL_LONGTERM implies FOLL_PIN */
+ rc = check_and_migrate_movable_pages(nr_pinned_pages, pages);
+ } while (rc == -EAGAIN);
+ memalloc_pin_restore(flags);
+ return rc ? rc : nr_pinned_pages;
}
-static bool is_valid_gup_flags(unsigned int gup_flags)
+/*
+ * Check that the given flags are valid for the exported gup/pup interface, and
+ * update them with the required flags that the caller must have set.
+ */
+static bool is_valid_gup_args(struct page **pages, int *locked,
+ unsigned int *gup_flags_p, unsigned int to_set)
{
+ unsigned int gup_flags = *gup_flags_p;
+
/*
- * FOLL_PIN must only be set internally by the pin_user_pages*() APIs,
- * never directly by the caller, so enforce that with an assertion:
- */
- if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
- return false;
- /*
- * FOLL_PIN is a prerequisite to FOLL_LONGTERM. Another way of saying
- * that is, FOLL_LONGTERM is a specific case, more restrictive case of
- * FOLL_PIN.
+ * These flags not allowed to be specified externally to the gup
+ * interfaces:
+ * - FOLL_TOUCH/FOLL_PIN/FOLL_TRIED/FOLL_FAST_ONLY are internal only
+ * - FOLL_REMOTE is internal only and used on follow_page()
+ * - FOLL_UNLOCKABLE is internal only and used if locked is !NULL
*/
- if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+ if (WARN_ON_ONCE(gup_flags & INTERNAL_GUP_FLAGS))
return false;
- return true;
-}
+ gup_flags |= to_set;
+ if (locked) {
+ /* At the external interface locked must be set */
+ if (WARN_ON_ONCE(*locked != 1))
+ return false;
-#ifdef CONFIG_MMU
-static long __get_user_pages_remote(struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
-{
- /*
- * Parts of FOLL_LONGTERM behavior are incompatible with
- * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
- * vmas. However, this only comes up if locked is set, and there are
- * callers that do request FOLL_LONGTERM, but do not set locked. So,
- * allow what we can.
- */
- if (gup_flags & FOLL_LONGTERM) {
- if (WARN_ON_ONCE(locked))
- return -EINVAL;
- /*
- * This will check the vmas (even if our vmas arg is NULL)
- * and return -ENOTSUPP if DAX isn't allowed in this case:
- */
- return __gup_longterm_locked(mm, start, nr_pages, pages,
- vmas, gup_flags | FOLL_TOUCH |
- FOLL_REMOTE);
+ gup_flags |= FOLL_UNLOCKABLE;
}
- return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
- locked,
- gup_flags | FOLL_TOUCH | FOLL_REMOTE);
+ /* FOLL_GET and FOLL_PIN are mutually exclusive. */
+ if (WARN_ON_ONCE((gup_flags & (FOLL_PIN | FOLL_GET)) ==
+ (FOLL_PIN | FOLL_GET)))
+ return false;
+
+ /* LONGTERM can only be specified when pinning */
+ if (WARN_ON_ONCE(!(gup_flags & FOLL_PIN) && (gup_flags & FOLL_LONGTERM)))
+ return false;
+
+ /* Pages input must be given if using GET/PIN */
+ if (WARN_ON_ONCE((gup_flags & (FOLL_GET | FOLL_PIN)) && !pages))
+ return false;
+
+ /* We want to allow the pgmap to be hot-unplugged at all times */
+ if (WARN_ON_ONCE((gup_flags & FOLL_LONGTERM) &&
+ (gup_flags & FOLL_PCI_P2PDMA)))
+ return false;
+
+ *gup_flags_p = gup_flags;
+ return true;
}
+#ifdef CONFIG_MMU
/**
* get_user_pages_remote() - pin user pages in memory
* @mm: mm_struct of target mm
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long. Or NULL, if caller
* only intends to ensure the pages are faulted in.
- * @vmas: array of pointers to vmas corresponding to each page.
- * Or NULL if the caller does not require them.
* @locked: pointer to lock flag indicating whether lock is held and
* subsequently whether VM_FAULT_RETRY functionality can be
* utilised. Lock must initially be held.
*
* The caller is responsible for releasing returned @pages, via put_page().
*
- * @vmas are valid only as long as mmap_lock is held.
- *
* Must be called with mmap_lock held for read or write.
*
* get_user_pages_remote walks a process's page tables and takes a reference
* This does not guarantee that the page exists in the user mappings when
* get_user_pages_remote returns, and there may even be a completely different
* page there in some cases (eg. if mmapped pagecache has been invalidated
- * and subsequently re faulted). However it does guarantee that the page
+ * and subsequently re-faulted). However it does guarantee that the page
* won't be freed completely. And mostly callers simply care that the page
* contains data that was valid *at some point in time*. Typically, an IO
* or similar operation cannot guarantee anything stronger anyway because
long get_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
+ int *locked)
{
- if (!is_valid_gup_flags(gup_flags))
+ int local_locked = 1;
+
+ if (!is_valid_gup_args(pages, locked, &gup_flags,
+ FOLL_TOUCH | FOLL_REMOTE))
return -EINVAL;
- return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
- pages, vmas, locked);
+ return __get_user_pages_locked(mm, start, nr_pages, pages,
+ locked ? locked : &local_locked,
+ gup_flags);
}
EXPORT_SYMBOL(get_user_pages_remote);
long get_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
-{
- return 0;
-}
-
-static long __get_user_pages_remote(struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
+ int *locked)
{
return 0;
}
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long. Or NULL, if caller
* only intends to ensure the pages are faulted in.
- * @vmas: array of pointers to vmas corresponding to each page.
- * Or NULL if the caller does not require them.
*
* This is the same as get_user_pages_remote(), just with a less-flexible
* calling convention where we assume that the mm being operated on belongs to
* obviously don't pass FOLL_REMOTE in here.
*/
long get_user_pages(unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas)
+ unsigned int gup_flags, struct page **pages)
{
- if (!is_valid_gup_flags(gup_flags))
+ int locked = 1;
+
+ if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_TOUCH))
return -EINVAL;
- return __gup_longterm_locked(current->mm, start, nr_pages,
- pages, vmas, gup_flags | FOLL_TOUCH);
+ return __get_user_pages_locked(current->mm, start, nr_pages, pages,
+ &locked, gup_flags);
}
EXPORT_SYMBOL(get_user_pages);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)
{
- struct mm_struct *mm = current->mm;
- int locked = 1;
- long ret;
+ int locked = 0;
- /*
- * FIXME: Current FOLL_LONGTERM behavior is incompatible with
- * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
- * vmas. As there are no users of this flag in this call we simply
- * disallow this option for now.
- */
- if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
+ if (!is_valid_gup_args(pages, NULL, &gup_flags,
+ FOLL_TOUCH | FOLL_UNLOCKABLE))
return -EINVAL;
- mmap_read_lock(mm);
- ret = __get_user_pages_locked(mm, start, nr_pages, pages, NULL,
- &locked, gup_flags | FOLL_TOUCH);
- if (locked)
- mmap_read_unlock(mm);
- return ret;
+ return __get_user_pages_locked(current->mm, start, nr_pages, pages,
+ &locked, gup_flags);
}
EXPORT_SYMBOL(get_user_pages_unlocked);
*/
#ifdef CONFIG_HAVE_FAST_GUP
+/*
+ * Used in the GUP-fast path to determine whether a pin is permitted for a
+ * specific folio.
+ *
+ * This call assumes the caller has pinned the folio, that the lowest page table
+ * level still points to this folio, and that interrupts have been disabled.
+ *
+ * Writing to pinned file-backed dirty tracked folios is inherently problematic
+ * (see comment describing the writable_file_mapping_allowed() function). We
+ * therefore try to avoid the most egregious case of a long-term mapping doing
+ * so.
+ *
+ * This function cannot be as thorough as that one as the VMA is not available
+ * in the fast path, so instead we whitelist known good cases and if in doubt,
+ * fall back to the slow path.
+ */
+static bool folio_fast_pin_allowed(struct folio *folio, unsigned int flags)
+{
+ struct address_space *mapping;
+ unsigned long mapping_flags;
+
+ /*
+ * If we aren't pinning then no problematic write can occur. A long term
+ * pin is the most egregious case so this is the one we disallow.
+ */
+ if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) !=
+ (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE))
+ return true;
+
+ /* The folio is pinned, so we can safely access folio fields. */
+
+ if (WARN_ON_ONCE(folio_test_slab(folio)))
+ return false;
+
+ /* hugetlb mappings do not require dirty-tracking. */
+ if (folio_test_hugetlb(folio))
+ return true;
+
+ /*
+ * GUP-fast disables IRQs. When IRQS are disabled, RCU grace periods
+ * cannot proceed, which means no actions performed under RCU can
+ * proceed either.
+ *
+ * inodes and thus their mappings are freed under RCU, which means the
+ * mapping cannot be freed beneath us and thus we can safely dereference
+ * it.
+ */
+ lockdep_assert_irqs_disabled();
+
+ /*
+ * However, there may be operations which _alter_ the mapping, so ensure
+ * we read it once and only once.
+ */
+ mapping = READ_ONCE(folio->mapping);
+
+ /*
+ * The mapping may have been truncated, in any case we cannot determine
+ * if this mapping is safe - fall back to slow path to determine how to
+ * proceed.
+ */
+ if (!mapping)
+ return false;
+
+ /* Anonymous folios pose no problem. */
+ mapping_flags = (unsigned long)mapping & PAGE_MAPPING_FLAGS;
+ if (mapping_flags)
+ return mapping_flags & PAGE_MAPPING_ANON;
+
+ /*
+ * At this point, we know the mapping is non-null and points to an
+ * address_space object. The only remaining whitelisted file system is
+ * shmem.
+ */
+ return shmem_mapping(mapping);
+}
+
static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start,
unsigned int flags,
struct page **pages)
}
#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
- unsigned int flags, struct page **pages, int *nr)
+/*
+ * Fast-gup relies on pte change detection to avoid concurrent pgtable
+ * operations.
+ *
+ * To pin the page, fast-gup needs to do below in order:
+ * (1) pin the page (by prefetching pte), then (2) check pte not changed.
+ *
+ * For the rest of pgtable operations where pgtable updates can be racy
+ * with fast-gup, we need to do (1) clear pte, then (2) check whether page
+ * is pinned.
+ *
+ * Above will work for all pte-level operations, including THP split.
+ *
+ * For THP collapse, it's a bit more complicated because fast-gup may be
+ * walking a pgtable page that is being freed (pte is still valid but pmd
+ * can be cleared already). To avoid race in such condition, we need to
+ * also check pmd here to make sure pmd doesn't change (corresponds to
+ * pmdp_collapse_flush() in the THP collapse code path).
+ */
+static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
+ unsigned long end, unsigned int flags,
+ struct page **pages, int *nr)
{
struct dev_pagemap *pgmap = NULL;
int nr_start = *nr, ret = 0;
pte_t *ptep, *ptem;
ptem = ptep = pte_offset_map(&pmd, addr);
+ if (!ptep)
+ return 0;
do {
pte_t pte = ptep_get_lockless(ptep);
struct page *page;
struct folio *folio;
/*
- * Similar to the PMD case below, NUMA hinting must take slow
- * path using the pte_protnone check.
+ * Always fallback to ordinary GUP on PROT_NONE-mapped pages:
+ * pte_access_permitted() better should reject these pages
+ * either way: otherwise, GUP-fast might succeed in
+ * cases where ordinary GUP would fail due to VMA access
+ * permissions.
*/
if (pte_protnone(pte))
goto pte_unmap;
if (!folio)
goto pte_unmap;
- if (unlikely(page_is_secretmem(page))) {
+ if (unlikely(folio_is_secretmem(folio))) {
+ gup_put_folio(folio, 1, flags);
+ goto pte_unmap;
+ }
+
+ if (unlikely(pmd_val(pmd) != pmd_val(*pmdp)) ||
+ unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
gup_put_folio(folio, 1, flags);
goto pte_unmap;
}
- if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+ if (!folio_fast_pin_allowed(folio, flags)) {
gup_put_folio(folio, 1, flags);
goto pte_unmap;
}
- if (!pte_write(pte) && gup_must_unshare(flags, page)) {
+ if (!pte_write(pte) && gup_must_unshare(NULL, flags, page)) {
gup_put_folio(folio, 1, flags);
goto pte_unmap;
}
* get_user_pages_fast_only implementation that can pin pages. Thus it's still
* useful to have gup_huge_pmd even if we can't operate on ptes.
*/
-static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
- unsigned int flags, struct page **pages, int *nr)
+static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
+ unsigned long end, unsigned int flags,
+ struct page **pages, int *nr)
{
return 0;
}
undo_dev_pagemap(nr, nr_start, flags, pages);
break;
}
+
+ if (!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
+ undo_dev_pagemap(nr, nr_start, flags, pages);
+ break;
+ }
+
SetPageReferenced(page);
pages[*nr] = page;
- if (unlikely(!try_grab_page(page, flags))) {
+ if (unlikely(try_grab_page(page, flags))) {
undo_dev_pagemap(nr, nr_start, flags, pages);
break;
}
if (!folio)
return 0;
- if (unlikely(pte_val(pte) != pte_val(*ptep))) {
+ if (unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
gup_put_folio(folio, refs, flags);
return 0;
}
- if (!pte_write(pte) && gup_must_unshare(flags, &folio->page)) {
+ if (!folio_fast_pin_allowed(folio, flags)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+
+ if (!pte_write(pte) && gup_must_unshare(NULL, flags, &folio->page)) {
gup_put_folio(folio, refs, flags);
return 0;
}
return 0;
}
- if (!pmd_write(orig) && gup_must_unshare(flags, &folio->page)) {
+ if (!folio_fast_pin_allowed(folio, flags)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+ if (!pmd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
gup_put_folio(folio, refs, flags);
return 0;
}
return 0;
}
- if (!pud_write(orig) && gup_must_unshare(flags, &folio->page)) {
+ if (!folio_fast_pin_allowed(folio, flags)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+
+ if (!pud_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
gup_put_folio(folio, refs, flags);
return 0;
}
return 0;
}
+ if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+
+ if (!folio_fast_pin_allowed(folio, flags)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+
*nr += refs;
folio_set_referenced(folio);
return 1;
pmdp = pmd_offset_lockless(pudp, pud, addr);
do {
- pmd_t pmd = READ_ONCE(*pmdp);
+ pmd_t pmd = pmdp_get_lockless(pmdp);
next = pmd_addr_end(addr, end);
if (!pmd_present(pmd))
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) ||
pmd_devmap(pmd))) {
- /*
- * NUMA hinting faults need to be handled in the GUP
- * slowpath for accounting purposes and so that they
- * can be serialised against THP migration.
- */
+ /* See gup_pte_range() */
if (pmd_protnone(pmd))
return 0;
if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr,
PMD_SHIFT, next, flags, pages, nr))
return 0;
- } else if (!gup_pte_range(pmd, addr, next, flags, pages, nr))
+ } else if (!gup_pte_range(pmd, pmdp, addr, next, flags, pages, nr))
return 0;
} while (pmdp++, addr = next, addr != end);
next = pud_addr_end(addr, end);
if (unlikely(!pud_present(pud)))
return 0;
- if (unlikely(pud_huge(pud))) {
+ if (unlikely(pud_huge(pud) || pud_devmap(pud))) {
if (!gup_huge_pud(pud, pudp, addr, next, flags,
pages, nr))
return 0;
}
#endif
-static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
- unsigned int gup_flags, struct page **pages)
-{
- int ret;
-
- /*
- * FIXME: FOLL_LONGTERM does not work with
- * get_user_pages_unlocked() (see comments in that function)
- */
- if (gup_flags & FOLL_LONGTERM) {
- mmap_read_lock(current->mm);
- ret = __gup_longterm_locked(current->mm,
- start, nr_pages,
- pages, NULL, gup_flags);
- mmap_read_unlock(current->mm);
- } else {
- ret = get_user_pages_unlocked(start, nr_pages,
- pages, gup_flags);
- }
-
- return ret;
-}
-
static unsigned long lockless_pages_from_mm(unsigned long start,
unsigned long end,
unsigned int gup_flags,
{
unsigned long len, end;
unsigned long nr_pinned;
+ int locked = 0;
int ret;
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
FOLL_FORCE | FOLL_PIN | FOLL_GET |
- FOLL_FAST_ONLY | FOLL_NOFAULT)))
+ FOLL_FAST_ONLY | FOLL_NOFAULT |
+ FOLL_PCI_P2PDMA | FOLL_HONOR_NUMA_FAULT)))
return -EINVAL;
if (gup_flags & FOLL_PIN)
start = untagged_addr(start) & PAGE_MASK;
len = nr_pages << PAGE_SHIFT;
if (check_add_overflow(start, len, &end))
- return 0;
+ return -EOVERFLOW;
+ if (end > TASK_SIZE_MAX)
+ return -EFAULT;
if (unlikely(!access_ok((void __user *)start, len)))
return -EFAULT;
/* Slow path: try to get the remaining pages with get_user_pages */
start += nr_pinned << PAGE_SHIFT;
pages += nr_pinned;
- ret = __gup_longterm_unlocked(start, nr_pages - nr_pinned, gup_flags,
- pages);
+ ret = __gup_longterm_locked(current->mm, start, nr_pages - nr_pinned,
+ pages, &locked,
+ gup_flags | FOLL_TOUCH | FOLL_UNLOCKABLE);
if (ret < 0) {
/*
* The caller has to unpin the pages we already pinned so
*
* Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
* the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
*
* If the architecture does not support this function, simply return with no
* pages pinned.
int get_user_pages_fast_only(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
{
- int nr_pinned;
/*
* Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
* because gup fast is always a "pin with a +1 page refcount" request.
* FOLL_FAST_ONLY is required in order to match the API description of
* this routine: no fall back to regular ("slow") GUP.
*/
- gup_flags |= FOLL_GET | FOLL_FAST_ONLY;
-
- nr_pinned = internal_get_user_pages_fast(start, nr_pages, gup_flags,
- pages);
-
- /*
- * As specified in the API description above, this routine is not
- * allowed to return negative values. However, the common core
- * routine internal_get_user_pages_fast() *can* return -errno.
- * Therefore, correct for that here:
- */
- if (nr_pinned < 0)
- nr_pinned = 0;
+ if (!is_valid_gup_args(pages, NULL, &gup_flags,
+ FOLL_GET | FOLL_FAST_ONLY))
+ return -EINVAL;
- return nr_pinned;
+ return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}
EXPORT_SYMBOL_GPL(get_user_pages_fast_only);
int get_user_pages_fast(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
{
- if (!is_valid_gup_flags(gup_flags))
- return -EINVAL;
-
/*
* The caller may or may not have explicitly set FOLL_GET; either way is
* OK. However, internally (within mm/gup.c), gup fast variants must set
* FOLL_GET, because gup fast is always a "pin with a +1 page refcount"
* request.
*/
- gup_flags |= FOLL_GET;
+ if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_GET))
+ return -EINVAL;
return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}
EXPORT_SYMBOL_GPL(get_user_pages_fast);
*
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
* see Documentation/core-api/pin_user_pages.rst for further details.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page() will not remove pins from it.
*/
int pin_user_pages_fast(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
{
- /* FOLL_GET and FOLL_PIN are mutually exclusive. */
- if (WARN_ON_ONCE(gup_flags & FOLL_GET))
- return -EINVAL;
-
- if (WARN_ON_ONCE(!pages))
+ if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_PIN))
return -EINVAL;
-
- gup_flags |= FOLL_PIN;
return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}
EXPORT_SYMBOL_GPL(pin_user_pages_fast);
-/*
- * This is the FOLL_PIN equivalent of get_user_pages_fast_only(). Behavior
- * is the same, except that this one sets FOLL_PIN instead of FOLL_GET.
- *
- * The API rules are the same, too: no negative values may be returned.
- */
-int pin_user_pages_fast_only(unsigned long start, int nr_pages,
- unsigned int gup_flags, struct page **pages)
-{
- int nr_pinned;
-
- /*
- * FOLL_GET and FOLL_PIN are mutually exclusive. Note that the API
- * rules require returning 0, rather than -errno:
- */
- if (WARN_ON_ONCE(gup_flags & FOLL_GET))
- return 0;
-
- if (WARN_ON_ONCE(!pages))
- return 0;
- /*
- * FOLL_FAST_ONLY is required in order to match the API description of
- * this routine: no fall back to regular ("slow") GUP.
- */
- gup_flags |= (FOLL_PIN | FOLL_FAST_ONLY);
- nr_pinned = internal_get_user_pages_fast(start, nr_pages, gup_flags,
- pages);
- /*
- * This routine is not allowed to return negative values. However,
- * internal_get_user_pages_fast() *can* return -errno. Therefore,
- * correct for that here:
- */
- if (nr_pinned < 0)
- nr_pinned = 0;
-
- return nr_pinned;
-}
-EXPORT_SYMBOL_GPL(pin_user_pages_fast_only);
-
/**
* pin_user_pages_remote() - pin pages of a remote process
*
* @gup_flags: flags modifying lookup behaviour
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long.
- * @vmas: array of pointers to vmas corresponding to each page.
- * Or NULL if the caller does not require them.
* @locked: pointer to lock flag indicating whether lock is held and
* subsequently whether VM_FAULT_RETRY functionality can be
* utilised. Lock must initially be held.
*
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
* see Documentation/core-api/pin_user_pages.rst for details.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page*() will not remove pins from it.
*/
long pin_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas, int *locked)
+ int *locked)
{
- /* FOLL_GET and FOLL_PIN are mutually exclusive. */
- if (WARN_ON_ONCE(gup_flags & FOLL_GET))
- return -EINVAL;
-
- if (WARN_ON_ONCE(!pages))
- return -EINVAL;
+ int local_locked = 1;
- gup_flags |= FOLL_PIN;
- return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
- pages, vmas, locked);
+ if (!is_valid_gup_args(pages, locked, &gup_flags,
+ FOLL_PIN | FOLL_TOUCH | FOLL_REMOTE))
+ return 0;
+ return __gup_longterm_locked(mm, start, nr_pages, pages,
+ locked ? locked : &local_locked,
+ gup_flags);
}
EXPORT_SYMBOL(pin_user_pages_remote);
* @gup_flags: flags modifying lookup behaviour
* @pages: array that receives pointers to the pages pinned.
* Should be at least nr_pages long.
- * @vmas: array of pointers to vmas corresponding to each page.
- * Or NULL if the caller does not require them.
*
* Nearly the same as get_user_pages(), except that FOLL_TOUCH is not set, and
* FOLL_PIN is set.
*
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
* see Documentation/core-api/pin_user_pages.rst for details.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page*() will not remove pins from it.
*/
long pin_user_pages(unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas)
+ unsigned int gup_flags, struct page **pages)
{
- /* FOLL_GET and FOLL_PIN are mutually exclusive. */
- if (WARN_ON_ONCE(gup_flags & FOLL_GET))
- return -EINVAL;
-
- if (WARN_ON_ONCE(!pages))
- return -EINVAL;
+ int locked = 1;
- gup_flags |= FOLL_PIN;
+ if (!is_valid_gup_args(pages, NULL, &gup_flags, FOLL_PIN))
+ return 0;
return __gup_longterm_locked(current->mm, start, nr_pages,
- pages, vmas, gup_flags);
+ pages, &locked, gup_flags);
}
EXPORT_SYMBOL(pin_user_pages);
* pin_user_pages_unlocked() is the FOLL_PIN variant of
* get_user_pages_unlocked(). Behavior is the same, except that this one sets
* FOLL_PIN and rejects FOLL_GET.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page*() will not remove pins from it.
*/
long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)
{
- /* FOLL_GET and FOLL_PIN are mutually exclusive. */
- if (WARN_ON_ONCE(gup_flags & FOLL_GET))
- return -EINVAL;
+ int locked = 0;
- if (WARN_ON_ONCE(!pages))
- return -EINVAL;
+ if (!is_valid_gup_args(pages, NULL, &gup_flags,
+ FOLL_PIN | FOLL_TOUCH | FOLL_UNLOCKABLE))
+ return 0;
- gup_flags |= FOLL_PIN;
- return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
+ return __gup_longterm_locked(current->mm, start, nr_pages, pages,
+ &locked, gup_flags);
}
EXPORT_SYMBOL(pin_user_pages_unlocked);
projects / linux-2.6-microblaze.git / blobdiff