Commit f9434ad1 authored Mar 23, 2011 by David Rientjes Committed by Linus Torvalds Mar 23, 2011

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>

parent 5a6475a4

mm/oom_kill.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -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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