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oom: add oom_kill_allocating_task sysctl

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Adds a new sysctl, 'oom_kill_allocating_task', which will automatically kill
the OOM-triggering task instead of scanning through the tasklist to find a
memory-hogging target.  This is helpful for systems with an insanely large
number of tasks where scanning the tasklist significantly degrades
performance.

Cc: Andrea Arcangeli <andrea@suse.de>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2007-10-16 23:25:56 -07:00 committed by Linus Torvalds
parent ff0ceb9deb
commit fe071d7e8a
3 changed files with 39 additions and 5 deletions
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22
Documentation/sysctl/vm.txt
View file

@ -31,6 +31,7 @@ Currently, these files are in /proc/sys/vm:
- min_unmapped_ratio
- min_slab_ratio
- panic_on_oom
- oom_kill_allocating_task
- mmap_min_address
- numa_zonelist_order
@ -220,6 +221,27 @@ The default value is 0.
1 and 2 are for failover of clustering. Please select either
according to your policy of failover.
=============================================================
oom_kill_allocating_task
This enables or disables killing the OOM-triggering task in
out-of-memory situations.
If this is set to zero, the OOM killer will scan through the entire
tasklist and select a task based on heuristics to kill. This normally
selects a rogue memory-hogging task that frees up a large amount of
memory when killed.
If this is set to non-zero, the OOM killer simply kills the task that
triggered the out-of-memory condition. This avoids the expensive
tasklist scan.
If panic_on_oom is selected, it takes precedence over whatever value
is used in oom_kill_allocating_task.
The default value is 0.
==============================================================
mmap_min_addr

9
kernel/sysctl.c
View file

@ -63,6 +63,7 @@ extern int print_fatal_signals;
extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
extern int sysctl_panic_on_oom;
extern int sysctl_oom_kill_allocating_task;
extern int max_threads;
extern int core_uses_pid;
extern int suid_dumpable;
@ -780,6 +781,14 @@ static ctl_table vm_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "oom_kill_allocating_task",
.data = &sysctl_oom_kill_allocating_task,
.maxlen = sizeof(sysctl_oom_kill_allocating_task),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{
.ctl_name = VM_OVERCOMMIT_RATIO,
.procname = "overcommit_ratio",

13
mm/oom_kill.c
View file

@ -27,6 +27,7 @@
#include <linux/notifier.h>
int sysctl_panic_on_oom;
int sysctl_oom_kill_allocating_task;
static DEFINE_MUTEX(zone_scan_mutex);
/* #define DEBUG */
@ -471,14 +472,16 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
"No available memory (MPOL_BIND)");
break;
case CONSTRAINT_CPUSET:
oom_kill_process(current, points,
"No available memory in cpuset");
break;
case CONSTRAINT_NONE:
if (sysctl_panic_on_oom)
panic("out of memory. panic_on_oom is selected\n");
/* Fall-through */
case CONSTRAINT_CPUSET:
if (sysctl_oom_kill_allocating_task) {
oom_kill_process(current, points,
"Out of memory (oom_kill_allocating_task)");
break;
}
retry:
/*
* Rambo mode: Shoot down a process and hope it solves whatever