From f9434ad1552427fab49336e1a6e3ef121895b9d1 Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Wed, 23 Mar 2011 16:42:44 -0700
Subject: [PATCH] memcg: give current access to memory reserves if it's trying
to die
When a memcg is oom and current has already received a SIGKILL, then give
it access to memory reserves with a higher scheduling priority so that it
may quickly exit and free its memory.
This is identical to the global oom killer and is done even before
checking for panic_on_oom: a pending SIGKILL here while panic_on_oom is
selected is guaranteed to have come from userspace; the thread only needs
access to memory reserves to exit and thus we don't unnecessarily panic
the machine until the kernel has no last resort to free memory.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/oom_kill.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3100bc57036b..62a5cec08a17 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -549,6 +549,17 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
unsigned int points = 0;
struct task_struct *p;
+ /*
+ * If current has a pending SIGKILL, then automatically select it. The
+ * goal is to allow it to allocate so that it may quickly exit and free
+ * its memory.
+ */
+ if (fatal_signal_pending(current)) {
+ set_thread_flag(TIF_MEMDIE);
+ boost_dying_task_prio(current, NULL);
+ return;
+ }
+
check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;
read_lock(&tasklist_lock);
--
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