linux-kernel - Re: Misleading OOM messages

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Date:	Thu, 14 May 2009 14:05:20 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Nick Piggin <npiggin@...e.de>, Mel Gorman <mel@....ul.ie>,
	Peter Ziljstra <a.p.ziljstra@...llo.nl>,
	San Mehat <san@...roid.com>, Arve Hj?nnev?g <arve@...roid.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Misleading OOM messages

On Thu, 2009-05-14 at 13:49 -0700, David Rientjes wrote:
> I think switching all the oom killer messages to be "no available memory" 
> as it is in the MPOL_BIND case would be the best alternative.  We 
> currently use "out of memory" even for cpusets, for example, when it 
> happens because it cannot accommodate any more hardwall allocations while 
> there may be an abundance of memory elsewhere that it cannot access.  I 
> also think "no available memory" makes more sense than "out of memory" 
> when describing situations where we're at or below the minimum watermarks 
> for all allowable zones.  Either that or "no allowable memory".

How about something like this to start?  We can "mv mm/oom_kill.c
mm/nam_kill.c" later. ;)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 92bcf1d..0ce0d59 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -409,7 +409,8 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 		return 0;
 	}
 
-	printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
+	printk(KERN_ERR "No available memory %s: "
+			"kill process %d (%s) score %li or a child\n",
 					message, task_pid_nr(p), p->comm, points);
 
 	/* Try to kill a child first */
@@ -438,7 +439,7 @@ retry:
 		p = current;
 
 	if (oom_kill_process(p, gfp_mask, 0, points, mem,
-				"Memory cgroup out of memory"))
+				"(memory cgroup)"))
 		goto retry;
 out:
 	read_unlock(&tasklist_lock);
@@ -519,7 +520,7 @@ static void __out_of_memory(gfp_t gfp_mask, int order)
 
 	if (sysctl_oom_kill_allocating_task)
 		if (!oom_kill_process(current, gfp_mask, order, 0, NULL,
-				"Out of memory (oom_kill_allocating_task)"))
+				"(oom_kill_allocating_task)"))
 			return;
 retry:
 	/*
@@ -537,8 +538,7 @@ retry:
 		panic("Out of memory and no killable processes...\n");
 	}
 
-	if (oom_kill_process(p, gfp_mask, order, points, NULL,
-			     "Out of memory"))
+	if (oom_kill_process(p, gfp_mask, order, points, NULL, ""))
 		goto retry;
 }
 
@@ -612,7 +612,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
 	switch (constraint) {
 	case CONSTRAINT_MEMORY_POLICY:
 		oom_kill_process(current, gfp_mask, order, 0, NULL,
-				"No available memory (MPOL_BIND)");
+				"(MPOL_BIND)");
 		break;
 
 	case CONSTRAINT_NONE:


-- Dave

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