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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2010-03-10 15:22:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-03-12 15:52:37 -0800
commitdaaf1e68874c078a15ae6ae827751839c4d81739 (patch)
tree22ed2e28b1c4f0b714df680ffff6407e519c5c60
parent1080d7a30304d03b1d9fd530aacd8aece2d702a2 (diff)
downloadlinux-2.6.34-ux500-daaf1e68874c078a15ae6ae827751839c4d81739.tar.gz
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>
-rw-r--r--Documentation/cgroups/memory.txt5
-rw-r--r--Documentation/sysctl/vm.txt5
-rw-r--r--mm/oom_kill.c2
3 files changed, 10 insertions, 2 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 268ab08222d..f8bc802d70b 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -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
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index fc5790d36cd..6c7d18c53f8 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
may be not fatal yet.
If this is set to 2, the kernel panics compulsorily even on the
-above-mentioned.
+above-mentioned. Even oom happens under memory cgroup, the whole
+system panics.
The default value is 0.
1 and 2 are for failover of clustering. Please select either
according to your policy of failover.
+panic_on_oom=2+kdump gives you very strong tool to investigate
+why oom happens. You can get snapshot.
=============================================================
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 35755a4156d..71d10bf52dc 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -473,6 +473,8 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
unsigned long points = 0;
struct task_struct *p;
+ if (sysctl_panic_on_oom == 2)
+ panic("out of memory(memcg). panic_on_oom is selected.\n");
read_lock(&tasklist_lock);
retry:
p = select_bad_process(&points, mem);