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mm/rmap: use rmap_walk() in page_referenced()

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Now, we have an infrastructure in rmap_walk() to handle difference from
variants of rmap traversing functions.

So, just use it in page_referenced().

In this patch, I change following things.

1. remove some variants of rmap traversing functions.
	cf> page_referenced_ksm, page_referenced_anon,
	page_referenced_file

2. introduce new struct page_referenced_arg and pass it to
   page_referenced_one(), main function of rmap_walk, in order to count
   reference, to store vm_flags and to check finish condition.

3. mechanical change to use rmap_walk() in page_referenced().

[liwanp@linux.vnet.ibm.com: fix BUG at rmap_walk]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joonsoo Kim 2014-01-21 15:49:53 -08:00 • committed by Linus Torvalds
parent e8351ac9bf
commit 9f32624be9
4 changed files with 80 additions and 194 deletions
Download patch file Download diff file Expand all files Collapse all files

210
mm/rmap.c
View file

@ -660,17 +660,22 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
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;
@ -682,13 +687,12 @@ int page_referenced_one(struct page *page, struct vm_area_struct *vma,
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() */
@ -704,13 +708,12 @@ int page_referenced_one(struct page *page, struct vm_area_struct *vma,
*/
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)) {
@ -727,113 +730,27 @@ int page_referenced_one(struct page *page, struct vm_area_struct *vma,
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;
struct page_referenced_arg *pra = arg;
struct mem_cgroup *memcg = pra->memcg;
/*
* 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));
if (!mm_match_cgroup(vma->vm_mm, memcg))
return true;
/*
* 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;
}
mutex_unlock(&mapping->i_mmap_mutex);
return referenced;
return false;
}
/**
@ -851,32 +768,47 @@ int page_referenced(struct page *page,
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,
@ -1700,6 +1632,14 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
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);
@ -1731,8 +1671,6 @@ done:
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))