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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2010-03-10 18:22:32 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2010-03-12 18:52:37 -0500
commitdaaf1e68874c078a15ae6ae827751839c4d81739 (patch)
tree22ed2e28b1c4f0b714df680ffff6407e519c5c60 /Documentation
parent1080d7a30304d03b1d9fd530aacd8aece2d702a2 (diff)
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 <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Nick Piggin <npiggin@suse.de> Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> 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/cgroups/memory.txt5
-rw-r--r--Documentation/sysctl/vm.txt5
2 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 268ab08222dd..f8bc802d70b9 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -182,6 +182,8 @@ list.
182NOTE: Reclaim does not work for the root cgroup, since we cannot set any 182NOTE: Reclaim does not work for the root cgroup, since we cannot set any
183limits on the root cgroup. 183limits on the root cgroup.
184 184
185Note2: When panic_on_oom is set to "2", the whole system will panic.
186
1852. Locking 1872. Locking
186 188
187The memory controller uses the following hierarchy 189The memory controller uses the following hierarchy
@@ -379,7 +381,8 @@ The feature can be disabled by
379NOTE1: Enabling/disabling will fail if the cgroup already has other 381NOTE1: Enabling/disabling will fail if the cgroup already has other
380cgroups created below it. 382cgroups created below it.
381 383
382NOTE2: This feature can be enabled/disabled per subtree. 384NOTE2: When panic_on_oom is set to "2", the whole system will panic in
385case of an oom event in any cgroup.
383 386
3847. Soft limits 3877. Soft limits
385 388
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index fc5790d36cd9..6c7d18c53f84 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -573,11 +573,14 @@ Because other nodes' memory may be free. This means system total status
573may be not fatal yet. 573may be not fatal yet.
574 574
575If this is set to 2, the kernel panics compulsorily even on the 575If this is set to 2, the kernel panics compulsorily even on the
576above-mentioned. 576above-mentioned. Even oom happens under memory cgroup, the whole
577system panics.
577 578
578The default value is 0. 579The default value is 0.
5791 and 2 are for failover of clustering. Please select either 5801 and 2 are for failover of clustering. Please select either
580according to your policy of failover. 581according to your policy of failover.
582panic_on_oom=2+kdump gives you very strong tool to investigate
583why oom happens. You can get snapshot.
581 584
582============================================================= 585=============================================================
583 586