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Date: Wed, 15 Jan 2014 18:43:08 -0500 From: Johannes Weiner <hannes@...xchg.org> To: Andrew Morton <akpm@...ux-foundation.org> Cc: David Rientjes <rientjes@...gle.com>, Michal Hocko <mhocko@...e.cz>, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: [patch] mm: oom_kill: revert 3% system memory bonus for privileged tasks With a63d83f427fb ("oom: badness heuristic rewrite"), the OOM killer tries to avoid killing privileged tasks by subtracting 3% of overall memory (system or cgroup) from their per-task consumption. But as a result, all root tasks that consume less than 3% of overall memory are considered equal, and so it only takes 33+ privileged tasks pushing the system out of memory for the OOM killer to do something stupid and kill sshd or dhclient. For example, on a 32G machine it can't tell the difference between the 1M agetty and the 10G fork bomb member. The changelog describes this 3% boost as the equivalent to the global overcommit limit being 3% higher for privileged tasks, but this is not the same as discounting 3% of overall memory from _every privileged task individually_ during OOM selection. Revert back to the old priority boost of pretending root tasks are only a quarter of their actual size. Signed-off-by: Johannes Weiner <hannes@...xchg.org> --- mm/oom_kill.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 1e4a600a6163..1b0011c3d9e2 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -166,11 +166,11 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, task_unlock(p); /* - * Root processes get 3% bonus, just like the __vm_enough_memory() - * implementation used by LSMs. + * Memory consumption being equal, prefer killing an + * unprivileged task over a root task. */ if (has_capability_noaudit(p, CAP_SYS_ADMIN)) - adj -= 30; + points /= 4; /* Normalize to oom_score_adj units */ adj *= totalpages / 1000; -- 1.8.4.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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