| Message ID | 1379705760-17033-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 08bcbd8..226b63e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4298,7 +4298,13 @@ static int compare_thresholds(const void *a, const void *b) const struct mem_cgroup_threshold *_a = a; const struct mem_cgroup_threshold *_b = b; - return _a->threshold - _b->threshold; + if (_a->threshold > _b->threshold) + return 1; + + if (_a->threshold < _b->threshold) + return -1; + + return 0; } static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
This is a note to let you know that I have just added a patch titled memcg: fix multiple large threshold notifications to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From a3b2e05fa1836fe8cd144169711390735b3a5415 Mon Sep 17 00:00:00 2001 From: Greg Thelen <gthelen@google.com> Date: Wed, 11 Sep 2013 14:23:08 -0700 Subject: [PATCH] memcg: fix multiple large threshold notifications commit 2bff24a3707093c435ab3241c47dcdb5f16e432b upstream. A memory cgroup with (1) multiple threshold notifications and (2) at least one threshold >=2G was not reliable. Specifically the notifications would either not fire or would not fire in the proper order. The __mem_cgroup_threshold() signaling logic depends on keeping 64 bit thresholds in sorted order. mem_cgroup_usage_register_event() sorts them with compare_thresholds(), which returns the difference of two 64 bit thresholds as an int. If the difference is positive but has bit[31] set, then sort() treats the difference as negative and breaks sort order. This fix compares the two arbitrary 64 bit thresholds returning the classic -1, 0, 1 result. The test below sets two notifications (at 0x1000 and 0x81001000): cd /sys/fs/cgroup/memory mkdir x for x in 4096 2164264960; do cgroup_event_listener x/memory.usage_in_bytes $x | sed "s/^/$x listener:/" & done echo $$ > x/cgroup.procs anon_leaker 500M v3.11-rc7 fails to signal the 4096 event listener: Leaking... Done leaking pages. Patched v3.11-rc7 properly notifies: Leaking... 4096 listener:2013:8:31:14:13:36 Done leaking pages. The fixed bug is old. It appears to date back to the introduction of memcg threshold notifications in v2.6.34-rc1-116-g2e72b6347c94 "memcg: implement memory thresholds" Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- mm/memcontrol.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) -- 1.8.3.2