/*
* When racing against e.g. zap_pte_range() on another cpu,
* in between its ptep_get_and_clear_full() and page_remove_rmap(),
- * try_to_unmap() may return false when it is about to become true,
+ * try_to_unmap() may return before page_mapped() has become false,
* if page table locking is skipped: use TTU_SYNC to wait for that.
*/
if (flags & TTU_SYNC)
pvmw.flags = PVMW_SYNC;
- /* munlock has nothing to gain from examining un-locked vmas */
- if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
- return true;
-
- if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) &&
- is_zone_device_page(page) && !is_device_private_page(page))
- return true;
-
- if (flags & TTU_SPLIT_HUGE_PMD) {
- split_huge_pmd_address(vma, address,
- flags & TTU_SPLIT_FREEZE, page);
- }
+ if (flags & TTU_SPLIT_HUGE_PMD)
+ split_huge_pmd_address(vma, address, false, page);
/*
* For THP, we have to assume the worse case ie pmd for invalidation.
mmu_notifier_invalidate_range_start(&range);
while (page_vma_mapped_walk(&pvmw)) {
-#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
- /* PMD-mapped THP migration entry */
- if (!pvmw.pte && (flags & TTU_MIGRATION)) {
- VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page);
-
- set_pmd_migration_entry(&pvmw, page);
- continue;
- }
-#endif
-
/*
* If the page is mlock()d, we cannot swap it out.
- * If it's recently referenced (perhaps page_referenced
- * skipped over this mm) then we should reactivate it.
*/
- if (!(flags & TTU_IGNORE_MLOCK)) {
- if (vma->vm_flags & VM_LOCKED) {
- /* PTE-mapped THP are never mlocked */
- if (!PageTransCompound(page)) {
- /*
- * Holding pte lock, we do *not* need
- * mmap_lock here
- */
- mlock_vma_page(page);
- }
- ret = false;
- page_vma_mapped_walk_done(&pvmw);
- break;
- }
- if (flags & TTU_MUNLOCK)
- continue;
+ if (!(flags & TTU_IGNORE_MLOCK) &&
+ (vma->vm_flags & VM_LOCKED)) {
+ /*
+ * PTE-mapped THP are never marked as mlocked: so do
+ * not set it on a DoubleMap THP, nor on an Anon THP
+ * (which may still be PTE-mapped after DoubleMap was
+ * cleared). But stop unmapping even in those cases.
+ */
+ if (!PageTransCompound(page) || (PageHead(page) &&
+ !PageDoubleMap(page) && !PageAnon(page)))
+ mlock_vma_page(page);
+ page_vma_mapped_walk_done(&pvmw);
+ ret = false;
+ break;
}
/* Unexpected PMD-mapped THP? */
}
}
- if (IS_ENABLED(CONFIG_MIGRATION) &&
- (flags & TTU_MIGRATION) &&
- is_zone_device_page(page)) {
- swp_entry_t entry;
- pte_t swp_pte;
-
- pteval = ptep_get_and_clear(mm, pvmw.address, pvmw.pte);
-
- /*
- * Store the pfn of the page in a special migration
- * pte. do_swap_page() will wait until the migration
- * pte is removed and then restart fault handling.
- */
- entry = make_migration_entry(page, 0);
- swp_pte = swp_entry_to_pte(entry);
-
- /*
- * pteval maps a zone device page and is therefore
- * a swap pte.
- */
- if (pte_swp_soft_dirty(pteval))
- swp_pte = pte_swp_mksoft_dirty(swp_pte);
- if (pte_swp_uffd_wp(pteval))
- swp_pte = pte_swp_mkuffd_wp(swp_pte);
- set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
- /*
- * No need to invalidate here it will synchronize on
- * against the special swap migration pte.
- *
- * The assignment to subpage above was computed from a
- * swap PTE which results in an invalid pointer.
- * Since only PAGE_SIZE pages can currently be
- * migrated, just set it to page. This will need to be
- * changed when hugepage migrations to device private
- * memory are supported.
- */
- subpage = page;
- goto discard;
- }
-
/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
if (should_defer_flush(mm, flags)) {
/* We have to invalidate as we cleared the pte */
mmu_notifier_invalidate_range(mm, address,
address + PAGE_SIZE);
- } else if (IS_ENABLED(CONFIG_MIGRATION) &&
- (flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))) {
- swp_entry_t entry;
- pte_t swp_pte;
-
- if (arch_unmap_one(mm, vma, address, pteval) < 0) {
- set_pte_at(mm, address, pvmw.pte, pteval);
- ret = false;
- page_vma_mapped_walk_done(&pvmw);
- break;
- }
-
- /*
- * Store the pfn of the page in a special migration
- * pte. do_swap_page() will wait until the migration
- * pte is removed and then restart fault handling.
- */
- entry = make_migration_entry(subpage,
- pte_write(pteval));
- swp_pte = swp_entry_to_pte(entry);
- if (pte_soft_dirty(pteval))
- swp_pte = pte_swp_mksoft_dirty(swp_pte);
- if (pte_uffd_wp(pteval))
- swp_pte = pte_swp_mkuffd_wp(swp_pte);
- set_pte_at(mm, address, pvmw.pte, swp_pte);
- /*
- * No need to invalidate here it will synchronize on
- * against the special swap migration pte.
- */
} else if (PageAnon(page)) {
swp_entry_t entry = { .val = page_private(subpage) };
pte_t swp_pte;
* Tries to remove all the page table entries which are mapping this
* page, used in the pageout path. Caller must hold the page lock.
*
- * If unmap is successful, return true. Otherwise, false.
+ * It is the caller's responsibility to check if the page is still
+ * mapped when needed (use TTU_SYNC to prevent accounting races).
*/
-bool try_to_unmap(struct page *page, enum ttu_flags flags)
+void try_to_unmap(struct page *page, enum ttu_flags flags)
{
struct rmap_walk_control rwc = {
.rmap_one = try_to_unmap_one,
.anon_lock = page_lock_anon_vma_read,
};
+ if (flags & TTU_RMAP_LOCKED)
+ rmap_walk_locked(page, &rwc);
+ else
+ rmap_walk(page, &rwc);
+}
+
+/*
+ * @arg: enum ttu_flags will be passed to this argument.
+ *
+ * If TTU_SPLIT_HUGE_PMD is specified any PMD mappings will be split into PTEs
+ * containing migration entries.
+ */
+static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, void *arg)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct page_vma_mapped_walk pvmw = {
+ .page = page,
+ .vma = vma,
+ .address = address,
+ };
+ pte_t pteval;
+ struct page *subpage;
+ bool ret = true;
+ struct mmu_notifier_range range;
+ enum ttu_flags flags = (enum ttu_flags)(long)arg;
+
+ /*
+ * When racing against e.g. zap_pte_range() on another cpu,
+ * in between its ptep_get_and_clear_full() and page_remove_rmap(),
+ * try_to_migrate() may return before page_mapped() has become false,
+ * if page table locking is skipped: use TTU_SYNC to wait for that.
+ */
+ if (flags & TTU_SYNC)
+ pvmw.flags = PVMW_SYNC;
+
+ /*
+ * unmap_page() in mm/huge_memory.c is the only user of migration with
+ * TTU_SPLIT_HUGE_PMD and it wants to freeze.
+ */
+ if (flags & TTU_SPLIT_HUGE_PMD)
+ split_huge_pmd_address(vma, address, true, page);
+
+ /*
+ * For THP, we have to assume the worse case ie pmd for invalidation.
+ * For hugetlb, it could be much worse if we need to do pud
+ * invalidation in the case of pmd sharing.
+ *
+ * Note that the page can not be free in this function as call of
+ * try_to_unmap() must hold a reference on the page.
+ */
+ range.end = PageKsm(page) ?
+ address + PAGE_SIZE : vma_address_end(page, vma);
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
+ address, range.end);
+ if (PageHuge(page)) {
+ /*
+ * If sharing is possible, start and end will be adjusted
+ * accordingly.
+ */
+ adjust_range_if_pmd_sharing_possible(vma, &range.start,
+ &range.end);
+ }
+ mmu_notifier_invalidate_range_start(&range);
+
+ while (page_vma_mapped_walk(&pvmw)) {
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ /* PMD-mapped THP migration entry */
+ if (!pvmw.pte) {
+ VM_BUG_ON_PAGE(PageHuge(page) ||
+ !PageTransCompound(page), page);
+
+ set_pmd_migration_entry(&pvmw, page);
+ continue;
+ }
+#endif
+
+ /* Unexpected PMD-mapped THP? */
+ VM_BUG_ON_PAGE(!pvmw.pte, page);
+
+ subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
+ address = pvmw.address;
+
+ if (PageHuge(page) && !PageAnon(page)) {
+ /*
+ * To call huge_pmd_unshare, i_mmap_rwsem must be
+ * held in write mode. Caller needs to explicitly
+ * do this outside rmap routines.
+ */
+ VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
+ if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
+ /*
+ * huge_pmd_unshare unmapped an entire PMD
+ * page. There is no way of knowing exactly
+ * which PMDs may be cached for this mm, so
+ * we must flush them all. start/end were
+ * already adjusted above to cover this range.
+ */
+ flush_cache_range(vma, range.start, range.end);
+ flush_tlb_range(vma, range.start, range.end);
+ mmu_notifier_invalidate_range(mm, range.start,
+ range.end);
+
+ /*
+ * The ref count of the PMD page was dropped
+ * which is part of the way map counting
+ * is done for shared PMDs. Return 'true'
+ * here. When there is no other sharing,
+ * huge_pmd_unshare returns false and we will
+ * unmap the actual page and drop map count
+ * to zero.
+ */
+ page_vma_mapped_walk_done(&pvmw);
+ break;
+ }
+ }
+
+ /* Nuke the page table entry. */
+ flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
+ pteval = ptep_clear_flush(vma, address, pvmw.pte);
+
+ /* Move the dirty bit to the page. Now the pte is gone. */
+ if (pte_dirty(pteval))
+ set_page_dirty(page);
+
+ /* Update high watermark before we lower rss */
+ update_hiwater_rss(mm);
+
+ if (is_zone_device_page(page)) {
+ swp_entry_t entry;
+ pte_t swp_pte;
+
+ /*
+ * Store the pfn of the page in a special migration
+ * pte. do_swap_page() will wait until the migration
+ * pte is removed and then restart fault handling.
+ */
+ entry = make_readable_migration_entry(
+ page_to_pfn(page));
+ swp_pte = swp_entry_to_pte(entry);
+
+ /*
+ * pteval maps a zone device page and is therefore
+ * a swap pte.
+ */
+ if (pte_swp_soft_dirty(pteval))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ if (pte_swp_uffd_wp(pteval))
+ swp_pte = pte_swp_mkuffd_wp(swp_pte);
+ set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
+ /*
+ * No need to invalidate here it will synchronize on
+ * against the special swap migration pte.
+ *
+ * The assignment to subpage above was computed from a
+ * swap PTE which results in an invalid pointer.
+ * Since only PAGE_SIZE pages can currently be
+ * migrated, just set it to page. This will need to be
+ * changed when hugepage migrations to device private
+ * memory are supported.
+ */
+ subpage = page;
+ } else if (PageHWPoison(page)) {
+ pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
+ if (PageHuge(page)) {
+ hugetlb_count_sub(compound_nr(page), mm);
+ set_huge_swap_pte_at(mm, address,
+ pvmw.pte, pteval,
+ vma_mmu_pagesize(vma));
+ } else {
+ dec_mm_counter(mm, mm_counter(page));
+ set_pte_at(mm, address, pvmw.pte, pteval);
+ }
+
+ } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
+ /*
+ * The guest indicated that the page content is of no
+ * interest anymore. Simply discard the pte, vmscan
+ * will take care of the rest.
+ * A future reference will then fault in a new zero
+ * page. When userfaultfd is active, we must not drop
+ * this page though, as its main user (postcopy
+ * migration) will not expect userfaults on already
+ * copied pages.
+ */
+ dec_mm_counter(mm, mm_counter(page));
+ /* We have to invalidate as we cleared the pte */
+ mmu_notifier_invalidate_range(mm, address,
+ address + PAGE_SIZE);
+ } else {
+ swp_entry_t entry;
+ pte_t swp_pte;
+
+ if (arch_unmap_one(mm, vma, address, pteval) < 0) {
+ set_pte_at(mm, address, pvmw.pte, pteval);
+ ret = false;
+ page_vma_mapped_walk_done(&pvmw);
+ break;
+ }
+
+ /*
+ * Store the pfn of the page in a special migration
+ * pte. do_swap_page() will wait until the migration
+ * pte is removed and then restart fault handling.
+ */
+ if (pte_write(pteval))
+ entry = make_writable_migration_entry(
+ page_to_pfn(subpage));
+ else
+ entry = make_readable_migration_entry(
+ page_to_pfn(subpage));
+
+ swp_pte = swp_entry_to_pte(entry);
+ if (pte_soft_dirty(pteval))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ if (pte_uffd_wp(pteval))
+ swp_pte = pte_swp_mkuffd_wp(swp_pte);
+ set_pte_at(mm, address, pvmw.pte, swp_pte);
+ /*
+ * No need to invalidate here it will synchronize on
+ * against the special swap migration pte.
+ */
+ }
+
+ /*
+ * No need to call mmu_notifier_invalidate_range() it has be
+ * done above for all cases requiring it to happen under page
+ * table lock before mmu_notifier_invalidate_range_end()
+ *
+ * See Documentation/vm/mmu_notifier.rst
+ */
+ page_remove_rmap(subpage, PageHuge(page));
+ put_page(page);
+ }
+
+ mmu_notifier_invalidate_range_end(&range);
+
+ return ret;
+}
+
+/**
+ * try_to_migrate - try to replace all page table mappings with swap entries
+ * @page: the page to replace page table entries for
+ * @flags: action and flags
+ *
+ * Tries to remove all the page table entries which are mapping this page and
+ * replace them with special swap entries. Caller must hold the page lock.
+ */
+void try_to_migrate(struct page *page, enum ttu_flags flags)
+{
+ struct rmap_walk_control rwc = {
+ .rmap_one = try_to_migrate_one,
+ .arg = (void *)flags,
+ .done = page_not_mapped,
+ .anon_lock = page_lock_anon_vma_read,
+ };
+
+ /*
+ * Migration always ignores mlock and only supports TTU_RMAP_LOCKED and
+ * TTU_SPLIT_HUGE_PMD and TTU_SYNC flags.
+ */
+ if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
+ TTU_SYNC)))
+ return;
+
+ if (is_zone_device_page(page) && !is_device_private_page(page))
+ return;
+
/*
* During exec, a temporary VMA is setup and later moved.
* The VMA is moved under the anon_vma lock but not the
* locking requirements of exec(), migration skips
* temporary VMAs until after exec() completes.
*/
- if ((flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))
- && !PageKsm(page) && PageAnon(page))
+ if (!PageKsm(page) && PageAnon(page))
rwc.invalid_vma = invalid_migration_vma;
if (flags & TTU_RMAP_LOCKED)
rmap_walk_locked(page, &rwc);
else
rmap_walk(page, &rwc);
+}
- /*
- * When racing against e.g. zap_pte_range() on another cpu,
- * in between its ptep_get_and_clear_full() and page_remove_rmap(),
- * try_to_unmap() may return false when it is about to become true,
- * if page table locking is skipped: use TTU_SYNC to wait for that.
- */
- return !page_mapcount(page);
+/*
+ * Walks the vma's mapping a page and mlocks the page if any locked vma's are
+ * found. Once one is found the page is locked and the scan can be terminated.
+ */
+static bool page_mlock_one(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, void *unused)
+{
+ struct page_vma_mapped_walk pvmw = {
+ .page = page,
+ .vma = vma,
+ .address = address,
+ };
+
+ /* An un-locked vma doesn't have any pages to lock, continue the scan */
+ if (!(vma->vm_flags & VM_LOCKED))
+ return true;
+
+ while (page_vma_mapped_walk(&pvmw)) {
+ /*
+ * Need to recheck under the ptl to serialise with
+ * __munlock_pagevec_fill() after VM_LOCKED is cleared in
+ * munlock_vma_pages_range().
+ */
+ if (vma->vm_flags & VM_LOCKED) {
+ /*
+ * PTE-mapped THP are never marked as mlocked; but
+ * this function is never called on a DoubleMap THP,
+ * nor on an Anon THP (which may still be PTE-mapped
+ * after DoubleMap was cleared).
+ */
+ mlock_vma_page(page);
+ /*
+ * No need to scan further once the page is marked
+ * as mlocked.
+ */
+ page_vma_mapped_walk_done(&pvmw);
+ return false;
+ }
+ }
+
+ return true;
}
/**
- * try_to_munlock - try to munlock a page
- * @page: the page to be munlocked
+ * page_mlock - try to mlock a page
+ * @page: the page to be mlocked
*
- * Called from munlock code. Checks all of the VMAs mapping the page
- * to make sure nobody else has this page mlocked. The page will be
- * returned with PG_mlocked cleared if no other vmas have it mlocked.
+ * Called from munlock code. Checks all of the VMAs mapping the page and mlocks
+ * the page if any are found. The page will be returned with PG_mlocked cleared
+ * if it is not mapped by any locked vmas.
*/
-
-void try_to_munlock(struct page *page)
+void page_mlock(struct page *page)
{
struct rmap_walk_control rwc = {
- .rmap_one = try_to_unmap_one,
- .arg = (void *)TTU_MUNLOCK,
+ .rmap_one = page_mlock_one,
.done = page_not_mapped,
.anon_lock = page_lock_anon_vma_read,
VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
+ /* Anon THP are only marked as mlocked when singly mapped */
+ if (PageTransCompound(page) && PageAnon(page))
+ return;
+
rmap_walk(page, &rwc);
}
+#ifdef CONFIG_DEVICE_PRIVATE
+struct make_exclusive_args {
+ struct mm_struct *mm;
+ unsigned long address;
+ void *owner;
+ bool valid;
+};
+
+static bool page_make_device_exclusive_one(struct page *page,
+ struct vm_area_struct *vma, unsigned long address, void *priv)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct page_vma_mapped_walk pvmw = {
+ .page = page,
+ .vma = vma,
+ .address = address,
+ };
+ struct make_exclusive_args *args = priv;
+ pte_t pteval;
+ struct page *subpage;
+ bool ret = true;
+ struct mmu_notifier_range range;
+ swp_entry_t entry;
+ pte_t swp_pte;
+
+ mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
+ vma->vm_mm, address, min(vma->vm_end,
+ address + page_size(page)), args->owner);
+ mmu_notifier_invalidate_range_start(&range);
+
+ while (page_vma_mapped_walk(&pvmw)) {
+ /* Unexpected PMD-mapped THP? */
+ VM_BUG_ON_PAGE(!pvmw.pte, page);
+
+ if (!pte_present(*pvmw.pte)) {
+ ret = false;
+ page_vma_mapped_walk_done(&pvmw);
+ break;
+ }
+
+ subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
+ address = pvmw.address;
+
+ /* Nuke the page table entry. */
+ flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
+ pteval = ptep_clear_flush(vma, address, pvmw.pte);
+
+ /* Move the dirty bit to the page. Now the pte is gone. */
+ if (pte_dirty(pteval))
+ set_page_dirty(page);
+
+ /*
+ * Check that our target page is still mapped at the expected
+ * address.
+ */
+ if (args->mm == mm && args->address == address &&
+ pte_write(pteval))
+ args->valid = true;
+
+ /*
+ * Store the pfn of the page in a special migration
+ * pte. do_swap_page() will wait until the migration
+ * pte is removed and then restart fault handling.
+ */
+ if (pte_write(pteval))
+ entry = make_writable_device_exclusive_entry(
+ page_to_pfn(subpage));
+ else
+ entry = make_readable_device_exclusive_entry(
+ page_to_pfn(subpage));
+ swp_pte = swp_entry_to_pte(entry);
+ if (pte_soft_dirty(pteval))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ if (pte_uffd_wp(pteval))
+ swp_pte = pte_swp_mkuffd_wp(swp_pte);
+
+ set_pte_at(mm, address, pvmw.pte, swp_pte);
+
+ /*
+ * There is a reference on the page for the swap entry which has
+ * been removed, so shouldn't take another.
+ */
+ page_remove_rmap(subpage, false);
+ }
+
+ mmu_notifier_invalidate_range_end(&range);
+
+ return ret;
+}
+
+/**
+ * page_make_device_exclusive - mark the page exclusively owned by a device
+ * @page: the page to replace page table entries for
+ * @mm: the mm_struct where the page is expected to be mapped
+ * @address: address where the page is expected to be mapped
+ * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier callbacks
+ *
+ * Tries to remove all the page table entries which are mapping this page and
+ * replace them with special device exclusive swap entries to grant a device
+ * exclusive access to the page. Caller must hold the page lock.
+ *
+ * Returns false if the page is still mapped, or if it could not be unmapped
+ * from the expected address. Otherwise returns true (success).
+ */
+static bool page_make_device_exclusive(struct page *page, struct mm_struct *mm,
+ unsigned long address, void *owner)
+{
+ struct make_exclusive_args args = {
+ .mm = mm,
+ .address = address,
+ .owner = owner,
+ .valid = false,
+ };
+ struct rmap_walk_control rwc = {
+ .rmap_one = page_make_device_exclusive_one,
+ .done = page_not_mapped,
+ .anon_lock = page_lock_anon_vma_read,
+ .arg = &args,
+ };
+
+ /*
+ * Restrict to anonymous pages for now to avoid potential writeback
+ * issues. Also tail pages shouldn't be passed to rmap_walk so skip
+ * those.
+ */
+ if (!PageAnon(page) || PageTail(page))
+ return false;
+
+ rmap_walk(page, &rwc);
+
+ return args.valid && !page_mapcount(page);
+}
+
+/**
+ * make_device_exclusive_range() - Mark a range for exclusive use by a device
+ * @mm: mm_struct of assoicated target process
+ * @start: start of the region to mark for exclusive device access
+ * @end: end address of region
+ * @pages: returns the pages which were successfully marked for exclusive access
+ * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier to allow filtering
+ *
+ * Returns: number of pages found in the range by GUP. A page is marked for
+ * exclusive access only if the page pointer is non-NULL.
+ *
+ * This function finds ptes mapping page(s) to the given address range, locks
+ * them and replaces mappings with special swap entries preventing userspace CPU
+ * access. On fault these entries are replaced with the original mapping after
+ * calling MMU notifiers.
+ *
+ * A driver using this to program access from a device must use a mmu notifier
+ * critical section to hold a device specific lock during programming. Once
+ * programming is complete it should drop the page lock and reference after
+ * which point CPU access to the page will revoke the exclusive access.
+ */
+int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
+ unsigned long end, struct page **pages,
+ void *owner)
+{
+ long npages = (end - start) >> PAGE_SHIFT;
+ long i;
+
+ npages = get_user_pages_remote(mm, start, npages,
+ FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
+ pages, NULL, NULL);
+ if (npages < 0)
+ return npages;
+
+ for (i = 0; i < npages; i++, start += PAGE_SIZE) {
+ if (!trylock_page(pages[i])) {
+ put_page(pages[i]);
+ pages[i] = NULL;
+ continue;
+ }
+
+ if (!page_make_device_exclusive(pages[i], mm, start, owner)) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ pages[i] = NULL;
+ }
+ }
+
+ return npages;
+}
+EXPORT_SYMBOL_GPL(make_device_exclusive_range);
+#endif
+
void __put_anon_vma(struct anon_vma *anon_vma)
{
struct anon_vma *root = anon_vma->root;
* Find all the mappings of a page using the mapping pointer and the vma chains
* contained in the anon_vma struct it points to.
*
- * When called from try_to_munlock(), the mmap_lock of the mm containing the vma
+ * When called from page_mlock(), the mmap_lock of the mm containing the vma
* where the page was found will be held for write. So, we won't recheck
* vm_flags for that VMA. That should be OK, because that vma shouldn't be
* LOCKED.
* Find all the mappings of a page using the mapping pointer and the vma chains
* contained in the address_space struct it points to.
*
- * When called from try_to_munlock(), the mmap_lock of the mm containing the vma
+ * When called from page_mlock(), the mmap_lock of the mm containing the vma
* where the page was found will be held for write. So, we won't recheck
* vm_flags for that VMA. That should be OK, because that vma shouldn't be
* LOCKED.
projects / linux-2.6-microblaze.git / blobdiff