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authorTejun Heo <tj@kernel.org>2016-01-15 16:57:16 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-15 17:56:32 -0800
commit654a0dd0953fcd87ff7bbb468fb889f0eb67df33 (patch)
tree790401b6c2c4cde86cf94a96823c6a9102781412 /fs
parent6f8d2b8a262c6b71e1464d488f41cccf9aafbc07 (diff)
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')
-rw-r--r--fs/fs-writeback.c2
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;