memcg: handle panic_on_oom=always case

Presently, if panic_on_oom=2, the whole system panics even if the oom
happend in some special situation (as cpuset, mempolicy....).  Then,
panic_on_oom=2 means painc_on_oom_always.

Now, memcg doesn't check panic_on_oom flag. This patch adds a check.

BTW, how it's useful ?

kdump+panic_on_oom=2 is the last tool to investigate what happens in
oom-ed system.  When a task is killed, the sysytem recovers and there will
be few hint to know what happnes.  In mission critical system, oom should
never happen.  Then, panic_on_oom=2+kdump is useful to avoid next OOM by
knowing precise information via snapshot.

TODO:
 - For memcg, it's for isolate system's memory usage, oom-notiifer and
   freeze_at_oom (or rest_at_oom) should be implemented. Then, management
   daemon can do similar jobs (as kdump) or taking snapshot per cgroup.

Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Nick Piggin <[email protected]>
Reviewed-by: Daisuke Nishimura <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
KAMEZAWA Hiroyuki 2010-03-10 15:22:32 -08:00 • committed by Linus Torvalds
commit daaf1e6887
3 changed files with 10 additions and 2 deletions

View file

@ -182,6 +182,8 @@ list.
NOTE: Reclaim does not work for the root cgroup, since we cannot set any
limits on the root cgroup.
Note2: When panic_on_oom is set to "2", the whole system will panic.
2. Locking
The memory controller uses the following hierarchy
@ -379,7 +381,8 @@ The feature can be disabled by
NOTE1: Enabling/disabling will fail if the cgroup already has other
cgroups created below it.
NOTE2: This feature can be enabled/disabled per subtree.
NOTE2: When panic_on_oom is set to "2", the whole system will panic in
case of an oom event in any cgroup.
7. Soft limits