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authorDavid Rientjes <rientjes@google.com>2012-03-21 16:34:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:54:58 -0700
commit08ab9b10d43aca091fdff58b69fc1ec89c5b8a83 (patch)
tree73abfd3a257f3feadc0fa28c3117aaa9d95af596 /mm/oom_kill.c
parentb76437579d1344b612cf1851ae610c636cec7db0 (diff)
downloadlinux-08ab9b10d43aca091fdff58b69fc1ec89c5b8a83.tar.gz
mm, oom: force oom kill on sysrq+f
The oom killer chooses not to kill a thread if: - an eligible thread has already been oom killed and has yet to exit, and - an eligible thread is exiting but has yet to free all its memory and is not the thread attempting to currently allocate memory. SysRq+F manually invokes the global oom killer to kill a memory-hogging task. This is normally done as a last resort to free memory when no progress is being made or to test the oom killer itself. For both uses, we always want to kill a thread and never defer. This patch causes SysRq+F to always kill an eligible thread and can be used to force a kill even if another oom killed thread has failed to exit. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/oom_kill.c')
-rw-r--r--mm/oom_kill.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 517299c808c..f23f3345464 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -310,7 +310,7 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
*/
static struct task_struct *select_bad_process(unsigned int *ppoints,
unsigned long totalpages, struct mem_cgroup *memcg,
- const nodemask_t *nodemask)
+ const nodemask_t *nodemask, bool force_kill)
{
struct task_struct *g, *p;
struct task_struct *chosen = NULL;
@@ -336,7 +336,8 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
if (unlikely(frozen(p)))
__thaw_task(p);
- return ERR_PTR(-1UL);
+ if (!force_kill)
+ return ERR_PTR(-1UL);
}
if (!p->mm)
continue;
@@ -354,7 +355,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
if (p == current) {
chosen = p;
*ppoints = 1000;
- } else {
+ } else if (!force_kill) {
/*
* If this task is not being ptraced on exit,
* then wait for it to finish before killing
@@ -572,7 +573,7 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask)
check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
limit = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT;
read_lock(&tasklist_lock);
- p = select_bad_process(&points, limit, memcg, NULL);
+ p = select_bad_process(&points, limit, memcg, NULL, false);
if (p && PTR_ERR(p) != -1UL)
oom_kill_process(p, gfp_mask, 0, points, limit, memcg, NULL,
"Memory cgroup out of memory");
@@ -687,6 +688,7 @@ static void clear_system_oom(void)
* @gfp_mask: memory allocation flags
* @order: amount of memory being requested as a power of 2
* @nodemask: nodemask passed to page allocator
+ * @force_kill: true if a task must be killed, even if others are exiting
*
* If we run out of memory, we have the choice between either
* killing a random task (bad), letting the system crash (worse)
@@ -694,7 +696,7 @@ static void clear_system_oom(void)
* don't have to be perfect here, we just have to be good.
*/
void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
- int order, nodemask_t *nodemask)
+ int order, nodemask_t *nodemask, bool force_kill)
{
const nodemask_t *mpol_mask;
struct task_struct *p;
@@ -738,7 +740,8 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
goto out;
}
- p = select_bad_process(&points, totalpages, NULL, mpol_mask);
+ p = select_bad_process(&points, totalpages, NULL, mpol_mask,
+ force_kill);
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
@@ -770,7 +773,7 @@ out:
void pagefault_out_of_memory(void)
{
if (try_set_system_oom()) {
- out_of_memory(NULL, 0, 0, NULL);
+ out_of_memory(NULL, 0, 0, NULL, false);
clear_system_oom();
}
if (!test_thread_flag(TIF_MEMDIE))