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Commit fe071d7e authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

oom: add oom_kill_allocating_task sysctl 



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: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ff0ceb9d

Documentation/sysctl/vm.txt

+22 −0
Original line number Diff line number Diff line
@@ -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

kernel/sysctl.c

+9 −0
Original line number Diff line number Diff line
@@ -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",

mm/oom_kill.c

+8 −5
Original line number Diff line number Diff line
@@ -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