3 files changed, 10 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.
 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 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
 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 35755a4156d6..71d10bf52dc8 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);