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More informative logging for OOM-killer

PATCH In review Arnout Engelen 2 participants 2 messages Jun 14, 2007 – Jun 15, 2007

Subsystems (4)
Memory management Documentation Proc sysctl Memory management - OOM killer
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Arnout Engelen

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PATCH 1/1 More informative logging for OOM-killer

Hi,

On a number of occasions I encountered machines which suffered from occasional OOM's, but tracking down what caused them was tricky because the OOM-killer only reported the process name of the process it killed, and this would be something non-conclusive like 'java' or 'python'.

I figured it'd be useful to report not only the process name, but also the parameters/commandline it had been started with.

The (text/plain) attached patch is a first shot at this. I'm not much of a kernel hacker, so this is probably not quite commit-worthy material yet - but I'm prepared to make changes if you guys can point me into the right direction here, and I won't feel insulted if someone else takes this over.

Let me know,

Arnout

Documentation/sysctl/vm.txt +10 -0
diff -aur linux-vanilla/Documentation/sysctl/vm.txt linux-hacked/Documentation/sysctl/vm.txt
@@ -31,6 +31,7 @@
 - min_unmapped_ratio
 - min_slab_ratio
 - panic_on_oom
+- informative_oom
 
 ==============================================================
 

@@ -205,3 +206,12 @@
 
 The default value is 0.
 
+=============================================================
+
+informative_oom
+
+This enables printing the commandline of processes killed by oom_killer. This
+will do an allocation at a point where the system is already low on memory, 
+but for most systems the improved diagnostics will be worth it.
+
+The default value is 1.
include/linux/sysctl.h +1 -0
diff -aur linux-vanilla/include/linux/sysctl.h linux-hacked/include/linux/sysctl.h
@@ -202,6 +202,7 @@
 	VM_PANIC_ON_OOM=33,	/* panic at out-of-memory */
 	VM_VDSO_ENABLED=34,	/* map VDSO into new processes? */
 	VM_MIN_SLAB=35,		 /* Percent pages ignored by zone reclaim */
+	VM_INFORMATIVE_OOM=36,	/* show commandline of oom_killed process */
 };
kernel/sysctl.c +9 -0
diff -aur linux-vanilla/kernel/sysctl.c linux-hacked/kernel/sysctl.c
@@ -64,6 +64,7 @@
 extern int sysctl_overcommit_memory;
 extern int sysctl_overcommit_ratio;
 extern int sysctl_panic_on_oom;
+extern int sysctl_informative_oom;
 extern int max_threads;
 extern int core_uses_pid;
 extern int suid_dumpable;

@@ -808,6 +809,14 @@
 		.proc_handler	= &proc_dointvec,
 	},
 	{
+		.ctl_name	= VM_INFORMATIVE_OOM,
+		.procname	= "informative_oom",
+		.data		= &sysctl_informative_oom,
+		.maxlen		= sizeof(sysctl_informative_oom),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+	{
 		.ctl_name	= VM_OVERCOMMIT_RATIO,
 		.procname	= "overcommit_ratio",
 		.data		= &sysctl_overcommit_ratio,
mm/oom_kill.c +54 -0

73 lines not on this page · raw message

#1 lore raw

mm/oom_kill.c line 339

Quoted 3 lines · On Thursday 14 June 2007 23:23:22 Arnout Engelen wrote:
mm/oom_kill.c +3 -0
+                       // TODO is this a proper upper bound for the
+                       // length of a commandline?
+                       char buffer[PAGE_SIZE / sizeof(char)];

That's a 100% guaranteed stack overflow with 4K stacks.

And sizeof(char) is always 1 btw.

-Andi

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