return new_page;
}
-int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg,
- unsigned long *vm_flags)
-{
- struct stable_node *stable_node;
- struct rmap_item *rmap_item;
- unsigned int mapcount = page_mapcount(page);
- int referenced = 0;
- int search_new_forks = 0;
-
- VM_BUG_ON(!PageKsm(page));
- VM_BUG_ON(!PageLocked(page));
-
- stable_node = page_stable_node(page);
- if (!stable_node)
- return 0;
-again:
- hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
- struct anon_vma *anon_vma = rmap_item->anon_vma;
- struct anon_vma_chain *vmac;
- struct vm_area_struct *vma;
-
- anon_vma_lock_read(anon_vma);
- anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
- 0, ULONG_MAX) {
- vma = vmac->vma;
- if (rmap_item->address < vma->vm_start ||
- rmap_item->address >= vma->vm_end)
- continue;
- /*
- * Initially we examine only the vma which covers this
- * rmap_item; but later, if there is still work to do,
- * we examine covering vmas in other mms: in case they
- * were forked from the original since ksmd passed.
- */
- if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
- continue;
-
- if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
- continue;
-
- referenced += page_referenced_one(page, vma,
- rmap_item->address, &mapcount, vm_flags);
- if (!search_new_forks || !mapcount)
- break;
- }
- anon_vma_unlock_read(anon_vma);
- if (!mapcount)
- goto out;
- }
- if (!search_new_forks++)
- goto again;
-out:
- return referenced;
-}
-
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
{
struct stable_node *stable_node;
int search_new_forks = 0;
VM_BUG_ON(!PageKsm(page));
+
+ /*
+ * Rely on the page lock to protect against concurrent modifications
+ * to that page's node of the stable tree.
+ */
VM_BUG_ON(!PageLocked(page));
stable_node = page_stable_node(page);
return 1;
}
+struct page_referenced_arg {
+ int mapcount;
+ int referenced;
+ unsigned long vm_flags;
+ struct mem_cgroup *memcg;
+};
/*
- * Subfunctions of page_referenced: page_referenced_one called
- * repeatedly from either page_referenced_anon or page_referenced_file.
+ * arg: page_referenced_arg will be passed
*/
int page_referenced_one(struct page *page, struct vm_area_struct *vma,
- unsigned long address, unsigned int *mapcount,
- unsigned long *vm_flags)
+ unsigned long address, void *arg)
{
struct mm_struct *mm = vma->vm_mm;
spinlock_t *ptl;
int referenced = 0;
+ struct page_referenced_arg *pra = arg;
if (unlikely(PageTransHuge(page))) {
pmd_t *pmd;
pmd = page_check_address_pmd(page, mm, address,
PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
if (!pmd)
- goto out;
+ return SWAP_AGAIN;
if (vma->vm_flags & VM_LOCKED) {
spin_unlock(ptl);
- *mapcount = 0; /* break early from loop */
- *vm_flags |= VM_LOCKED;
- goto out;
+ pra->vm_flags |= VM_LOCKED;
+ return SWAP_FAIL; /* To break the loop */
}
/* go ahead even if the pmd is pmd_trans_splitting() */
*/
pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
- goto out;
+ return SWAP_AGAIN;
if (vma->vm_flags & VM_LOCKED) {
pte_unmap_unlock(pte, ptl);
- *mapcount = 0; /* break early from loop */
- *vm_flags |= VM_LOCKED;
- goto out;
+ pra->vm_flags |= VM_LOCKED;
+ return SWAP_FAIL; /* To break the loop */
}
if (ptep_clear_flush_young_notify(vma, address, pte)) {
pte_unmap_unlock(pte, ptl);
}
- (*mapcount)--;
-
- if (referenced)
- *vm_flags |= vma->vm_flags;
-out:
- return referenced;
-}
-
-static int page_referenced_anon(struct page *page,
- struct mem_cgroup *memcg,
- unsigned long *vm_flags)
-{
- unsigned int mapcount;
- struct anon_vma *anon_vma;
- pgoff_t pgoff;
- struct anon_vma_chain *avc;
- int referenced = 0;
-
- anon_vma = page_lock_anon_vma_read(page);
- if (!anon_vma)
- return referenced;
-
- mapcount = page_mapcount(page);
- pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
- struct vm_area_struct *vma = avc->vma;
- unsigned long address = vma_address(page, vma);
- /*
- * If we are reclaiming on behalf of a cgroup, skip
- * counting on behalf of references from different
- * cgroups
- */
- if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
- continue;
- referenced += page_referenced_one(page, vma, address,
- &mapcount, vm_flags);
- if (!mapcount)
- break;
+ if (referenced) {
+ pra->referenced++;
+ pra->vm_flags |= vma->vm_flags;
}
- page_unlock_anon_vma_read(anon_vma);
- return referenced;
+ pra->mapcount--;
+ if (!pra->mapcount)
+ return SWAP_SUCCESS; /* To break the loop */
+
+ return SWAP_AGAIN;
}
-/**
- * page_referenced_file - referenced check for object-based rmap
- * @page: the page we're checking references on.
- * @memcg: target memory control group
- * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
- *
- * For an object-based mapped page, find all the places it is mapped and
- * check/clear the referenced flag. This is done by following the page->mapping
- * pointer, then walking the chain of vmas it holds. It returns the number
- * of references it found.
- *
- * This function is only called from page_referenced for object-based pages.
- */
-static int page_referenced_file(struct page *page,
- struct mem_cgroup *memcg,
- unsigned long *vm_flags)
+static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
{
- unsigned int mapcount;
- struct address_space *mapping = page->mapping;
- pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- struct vm_area_struct *vma;
- int referenced = 0;
-
- /*
- * The caller's checks on page->mapping and !PageAnon have made
- * sure that this is a file page: the check for page->mapping
- * excludes the case just before it gets set on an anon page.
- */
- BUG_ON(PageAnon(page));
+ struct page_referenced_arg *pra = arg;
+ struct mem_cgroup *memcg = pra->memcg;
- /*
- * The page lock not only makes sure that page->mapping cannot
- * suddenly be NULLified by truncation, it makes sure that the
- * structure at mapping cannot be freed and reused yet,
- * so we can safely take mapping->i_mmap_mutex.
- */
- BUG_ON(!PageLocked(page));
-
- mutex_lock(&mapping->i_mmap_mutex);
-
- /*
- * i_mmap_mutex does not stabilize mapcount at all, but mapcount
- * is more likely to be accurate if we note it after spinning.
- */
- mapcount = page_mapcount(page);
-
- vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
- unsigned long address = vma_address(page, vma);
- /*
- * If we are reclaiming on behalf of a cgroup, skip
- * counting on behalf of references from different
- * cgroups
- */
- if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
- continue;
- referenced += page_referenced_one(page, vma, address,
- &mapcount, vm_flags);
- if (!mapcount)
- break;
- }
+ if (!mm_match_cgroup(vma->vm_mm, memcg))
+ return true;
- mutex_unlock(&mapping->i_mmap_mutex);
- return referenced;
+ return false;
}
/**
struct mem_cgroup *memcg,
unsigned long *vm_flags)
{
- int referenced = 0;
+ int ret;
int we_locked = 0;
+ struct page_referenced_arg pra = {
+ .mapcount = page_mapcount(page),
+ .memcg = memcg,
+ };
+ struct rmap_walk_control rwc = {
+ .rmap_one = page_referenced_one,
+ .arg = (void *)&pra,
+ .anon_lock = page_lock_anon_vma_read,
+ };
*vm_flags = 0;
- if (page_mapped(page) && page_rmapping(page)) {
- if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
- we_locked = trylock_page(page);
- if (!we_locked) {
- referenced++;
- goto out;
- }
- }
- if (unlikely(PageKsm(page)))
- referenced += page_referenced_ksm(page, memcg,
- vm_flags);
- else if (PageAnon(page))
- referenced += page_referenced_anon(page, memcg,
- vm_flags);
- else if (page->mapping)
- referenced += page_referenced_file(page, memcg,
- vm_flags);
- if (we_locked)
- unlock_page(page);
+ if (!page_mapped(page))
+ return 0;
+
+ if (!page_rmapping(page))
+ return 0;
+
+ if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
+ we_locked = trylock_page(page);
+ if (!we_locked)
+ return 1;
}
-out:
- return referenced;
+
+ /*
+ * If we are reclaiming on behalf of a cgroup, skip
+ * counting on behalf of references from different
+ * cgroups
+ */
+ if (memcg) {
+ rwc.invalid_vma = invalid_page_referenced_vma;
+ }
+
+ ret = rmap_walk(page, &rwc);
+ *vm_flags = pra.vm_flags;
+
+ if (we_locked)
+ unlock_page(page);
+
+ return pra.referenced;
}
static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
struct vm_area_struct *vma;
int ret = SWAP_AGAIN;
+ /*
+ * The page lock not only makes sure that page->mapping cannot
+ * suddenly be NULLified by truncation, it makes sure that the
+ * structure at mapping cannot be freed and reused yet,
+ * so we can safely take mapping->i_mmap_mutex.
+ */
+ VM_BUG_ON(!PageLocked(page));
+
if (!mapping)
return ret;
mutex_lock(&mapping->i_mmap_mutex);
int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
{
- VM_BUG_ON(!PageLocked(page));
-
if (unlikely(PageKsm(page)))
return rmap_walk_ksm(page, rwc);
else if (PageAnon(page))
projects / cascardo / linux.git / commitdiff