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| author | Tejun Heo <tj@kernel.org> | 2016-01-15 16:57:16 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-15 17:56:32 -0800 |
| commit | 654a0dd0953fcd87ff7bbb468fb889f0eb67df33 (patch) | |
| tree | 790401b6c2c4cde86cf94a96823c6a9102781412 /fs/fs-writeback.c | |
| parent | 6f8d2b8a262c6b71e1464d488f41cccf9aafbc07 (diff) | |
| download | lwn-654a0dd0953fcd87ff7bbb468fb889f0eb67df33.tar.gz lwn-654a0dd0953fcd87ff7bbb468fb889f0eb67df33.zip | |
cgroup, memcg, writeback: drop spurious rcu locking around mem_cgroup_css_from_page()
In earlier versions, mem_cgroup_css_from_page() could return non-root
css on a legacy hierarchy which can go away and required rcu locking;
however, the eventual version simply returns the root cgroup if memcg is
on a legacy hierarchy and thus doesn't need rcu locking around or in it.
Remove spurious rcu lockings.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fs-writeback.c')
| -rw-r--r-- | fs/fs-writeback.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 023f6a1f23cd..6915c950e6e8 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -677,9 +677,7 @@ void wbc_account_io(struct writeback_control *wbc, struct page *page, if (!wbc->wb) return; - rcu_read_lock(); id = mem_cgroup_css_from_page(page)->id; - rcu_read_unlock(); if (id == wbc->wb_id) { wbc->wb_bytes += bytes; |