From 08ab9b10d43aca091fdff58b69fc1ec89c5b8a83 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 21 Mar 2012 16:34:04 -0700 Subject: 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 Acked-by: KOSAKI Motohiro Acked-by: Pekka Enberg Acked-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/tty/sysrq.c | 2 +- include/linux/oom.h | 2 +- mm/oom_kill.c | 17 ++++++++++------- mm/page_alloc.c | 2 +- 4 files changed, 13 insertions(+), 10 deletions(-) diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index ecb8e2203ac..136e86faa1e 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -346,7 +346,7 @@ static struct sysrq_key_op sysrq_term_op = { static void moom_callback(struct work_struct *ignored) { - out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL); + out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL, true); } static DECLARE_WORK(moom_work, moom_callback); diff --git a/include/linux/oom.h b/include/linux/oom.h index 552fba9c7d5..3d7647536b0 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -49,7 +49,7 @@ extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags); extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags); extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, - int order, nodemask_t *mask); + int order, nodemask_t *mask, bool force_kill); extern int register_oom_notifier(struct notifier_block *nb); extern int unregister_oom_notifier(struct notifier_block *nb); 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)) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 572b93ea475..98552cf1da8 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1968,7 +1968,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, goto out; } /* Exhausted what can be done so it's blamo time */ - out_of_memory(zonelist, gfp_mask, order, nodemask); + out_of_memory(zonelist, gfp_mask, order, nodemask, false); out: clear_zonelist_oom(zonelist, gfp_mask); -- cgit v1.2.3