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| author | Greg Thelen <gthelen@google.com> | 2013-09-11 23:23:08 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-12 00:58:15 +0200 |
| commit | 2bff24a3707093c435ab3241c47dcdb5f16e432b (patch) | |
| tree | d4ffa7de9ca2d7366de1f45297121517fb70dbd5 /mm/memcontrol.c | |
| parent | mm/mempool.c: convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...) (diff) | |
| download | linux-2bff24a3707093c435ab3241c47dcdb5f16e432b.tar.xz linux-2bff24a3707093c435ab3241c47dcdb5f16e432b.zip | |
memcg: fix multiple large threshold notifications
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5ca1dcf77ce9..c6bd28edd533 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5591,7 +5591,13 @@ 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) |