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mm: simplify lock_page_memcg()

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Now that migration doesn't clear page->mem_cgroup of live pages anymore,
it's safe to make lock_page_memcg() and the memcg stat functions take
pages, and spare the callers from memcg objects.

[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner
2016-03-15 14:57:22 -07:00
committed by Linus Torvalds
parent 6a93ca8fde
commit 62cccb8c8e
12 changed files with 88 additions and 117 deletions
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23
mm/memcontrol.c
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@@ -1690,7 +1690,7 @@ cleanup:
* This function protects unlocked LRU pages from being moved to
* another cgroup and stabilizes their page->mem_cgroup binding.
*/
struct mem_cgroup *lock_page_memcg(struct page *page)
void lock_page_memcg(struct page *page)
{
struct mem_cgroup *memcg;
unsigned long flags;
@@ -1699,25 +1699,18 @@ struct mem_cgroup *lock_page_memcg(struct page *page)
* The RCU lock is held throughout the transaction. The fast
* path can get away without acquiring the memcg->move_lock
* because page moving starts with an RCU grace period.
*
* The RCU lock also protects the memcg from being freed when
* the page state that is going to change is the only thing
* preventing the page from being uncharged.
* E.g. end-writeback clearing PageWriteback(), which allows
* migration to go ahead and uncharge the page before the
* account transaction might be complete.
*/
rcu_read_lock();
if (mem_cgroup_disabled())
return NULL;
return;
again:
memcg = page->mem_cgroup;
if (unlikely(!memcg))
return NULL;
return;
if (atomic_read(&memcg->moving_account) <= 0)
return memcg;
return;
spin_lock_irqsave(&memcg->move_lock, flags);
if (memcg != page->mem_cgroup) {
@@ -1733,16 +1726,18 @@ again:
memcg->move_lock_task = current;
memcg->move_lock_flags = flags;
return memcg;
return;
}
EXPORT_SYMBOL(lock_page_memcg);
/**
* unlock_page_memcg - unlock a page->mem_cgroup binding
* @memcg: the memcg returned by lock_page_memcg()
* @page: the page
*/
void unlock_page_memcg(struct mem_cgroup *memcg)
void unlock_page_memcg(struct page *page)
{
struct mem_cgroup *memcg = page->mem_cgroup;
if (memcg && memcg->move_lock_task == current) {
unsigned long flags = memcg->move_lock_flags;