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authorHugh Dickins <hughd@google.com>2012-03-21 16:34:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:55:01 -0700
commit42aee6c495e07dba7410b863a360db6bb9ec6d66 (patch)
treed014b2b5c7aa9d1a1f13686fa06699f9f734ee1c /include/linux/cgroup.h
parent9f7de8275b46d9d11b1505adbfe6c2bb48df4741 (diff)
cgroup: revert ss_id_lock to spinlock
Commit c1e2ee2dc436 ("memcg: replace ss->id_lock with a rwlock") has now been seen to cause the unfair behavior we should have expected from converting a spinlock to an rwlock: softlockup in cgroup_mkdir(), whose get_new_cssid() is waiting for the wlock, while there are 19 tasks using the rlock in css_get_next() to get on with their memcg workload (in an artificial test, admittedly). Yet lib/idr.c was made suitable for RCU way back: revert that commit, restoring ss->id_lock to a spinlock. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 501adb1b2f4..5a85b3415c1 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -498,7 +498,7 @@ struct cgroup_subsys {
struct list_head sibling;
/* used when use_id == true */
struct idr idr;
- rwlock_t id_lock;
+ spinlock_t id_lock;
/* should be defined only by modular subsystems */
struct module *module;