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authorRoman Gushchin <guro@fb.com>2018-08-21 21:53:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:45 -0700
commit3d8b38eb81cac81395f6a823f6bf401b327268e6 (patch)
treedc0f23ff3a3b8a3d13706fd35afbd522b8c4b0c6 /Documentation
parent5989ad7b5ede38d605c588981f634c08252abfc3 (diff)
mm, oom: introduce memory.oom.group
For some workloads an intervention from the OOM killer can be painful. Killing a random task can bring the workload into an inconsistent state. Historically, there are two common solutions for this problem: 1) enabling panic_on_oom, 2) using a userspace daemon to monitor OOMs and kill all outstanding processes. Both approaches have their downsides: rebooting on each OOM is an obvious waste of capacity, and handling all in userspace is tricky and requires a userspace agent, which will monitor all cgroups for OOMs. In most cases an in-kernel after-OOM cleaning-up mechanism can eliminate the necessity of enabling panic_on_oom. Also, it can simplify the cgroup management for userspace applications. This commit introduces a new knob for cgroup v2 memory controller: memory.oom.group. The knob determines whether the cgroup should be treated as an indivisible workload by the OOM killer. If set, all tasks belonging to the cgroup or to its descendants (if the memory cgroup is not a leaf cgroup) are killed together or not at all. To determine which cgroup has to be killed, we do traverse the cgroup hierarchy from the victim task's cgroup up to the OOMing cgroup (or root) and looking for the highest-level cgroup with memory.oom.group set. Tasks with the OOM protection (oom_score_adj set to -1000) are treated as an exception and are never killed. This patch doesn't change the OOM victim selection algorithm. Link: http://lkml.kernel.org/r/20180802003201.817-4-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst18
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 1746131bc9cb..184193bcb262 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1072,6 +1072,24 @@ PAGE_SIZE multiple when read back.
high limit is used and monitored properly, this limit's
utility is limited to providing the final safety net.
+ memory.oom.group
+ A read-write single value file which exists on non-root
+ cgroups. The default value is "0".
+
+ Determines whether the cgroup should be treated as
+ an indivisible workload by the OOM killer. If set,
+ all tasks belonging to the cgroup or to its descendants
+ (if the memory cgroup is not a leaf cgroup) are killed
+ together or not at all. This can be used to avoid
+ partial kills to guarantee workload integrity.
+
+ Tasks with the OOM protection (oom_score_adj set to -1000)
+ are treated as an exception and are never killed.
+
+ If the OOM killer is invoked in a cgroup, it's not going
+ to kill any tasks outside of this cgroup, regardless
+ memory.oom.group values of ancestor cgroups.
+
memory.events
A read-only flat-keyed file which exists on non-root cgroups.
The following entries are defined. Unless specified