linux-kernel - [patch 10/11 -mmotm] oom: avoid oom kill if no interruptible tasks

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Message-ID: <alpine.DEB.2.00.0905101502470.18804@chino.kir.corp.google.com>
Date:	Sun, 10 May 2009 15:07:25 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Greg Kroah-Hartman <gregkh@...e.de>, Nick Piggin <npiggin@...e.de>,
	Mel Gorman <mel@....ul.ie>,
	Peter Ziljstra <a.p.ziljstra@...llo.nl>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	San Mehat <san@...roid.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	linux-kernel@...r.kernel.org
Subject: [patch 10/11 -mmotm] oom: avoid oom kill if no interruptible tasks

If there are no interruptible system tasks other than kthreads, no task
should be chosen for oom kill since they won't respond to the SIGKILL
anyway.  Instead, we choose to simply fail page allocations if reclaim
cannot free memory and hope for the best.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 mm/oom_kill.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -209,6 +209,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
 	struct task_struct *g, *p;
 	struct task_struct *chosen = NULL;
 	struct timespec uptime;
+	unsigned long nr_interruptible = 0;
 	*ppoints = 0;
 	*freed = 0;
 
@@ -225,6 +226,8 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
 		/* skip the init task */
 		if (is_global_init(p))
 			continue;
+		if (!(p->state & TASK_UNINTERRUPTIBLE))
+			nr_interruptible++;
 		if (mem && !task_in_mem_cgroup(p, mem))
 			continue;
 
@@ -277,7 +280,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
 		}
 	} while_each_thread(g, p);
 
-	return chosen;
+	return nr_interruptible ? chosen : ERR_PTR(-1UL);
 }
 
 /**
--
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