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Commit d31f56db authored by Daisuke Nishimura's avatar Daisuke Nishimura Committed by Linus Torvalds
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memcg: avoid oom-killing innocent task in case of use_hierarchy 



task_in_mem_cgroup(), which is called by select_bad_process() to check
whether a task can be a candidate for being oom-killed from memcg's limit,
checks "curr->use_hierarchy"("curr" is the mem_cgroup the task belongs
to).

But this check return true(it's false positive) when:

	<some path>/aa		use_hierarchy == 0	<- hitting limit
	  <some path>/aa/00	use_hierarchy == 1	<- the task belongs to

This leads to killing an innocent task in aa/00.  This patch is a fix for
this bug.  And this patch also fixes the arg for
mem_cgroup_print_oom_info().  We should print information of mem_cgroup
which the task being killed, not current, belongs to.

Signed-off-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: default avatarBalbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 57f9fd7d

mm/memcontrol.c

+8 −2
Original line number Diff line number Diff line
@@ -760,7 +760,13 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem) 
	task_unlock(task);

	if (!curr)

		return 0;

	if (curr->use_hierarchy)

	/*

	 * We should check use_hierarchy of "mem" not "curr". Because checking

	 * use_hierarchy of "curr" here make this function true if hierarchy is

	 * enabled in "curr" and "curr" is a child of "mem" in *cgroup*

	 * hierarchy(even if use_hierarchy is disabled in "mem").

	 */

	if (mem->use_hierarchy)

		ret = css_is_ancestor(&curr->css, &mem->css);

	else

		ret = (curr == mem);
@@ -1009,7 +1015,7 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) 
	static char memcg_name[PATH_MAX];

	int ret;



	if (!memcg)

	if (!memcg || !p)

		return;

mm/oom_kill.c

+7 −6
Original line number Diff line number Diff line
@@ -356,7 +356,8 @@ static void dump_tasks(const struct mem_cgroup *mem) 
	} while_each_thread(g, p);

}



static void dump_header(gfp_t gfp_mask, int order, struct mem_cgroup *mem)

static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,

							struct mem_cgroup *mem)

{

	pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "

		"oom_adj=%d\n",
@@ -365,7 +366,7 @@ static void dump_header(gfp_t gfp_mask, int order, struct mem_cgroup *mem) 
	cpuset_print_task_mems_allowed(current);

	task_unlock(current);

	dump_stack();

	mem_cgroup_print_oom_info(mem, current);

	mem_cgroup_print_oom_info(mem, p);

	show_mem();

	if (sysctl_oom_dump_tasks)

		dump_tasks(mem);
@@ -440,7 +441,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 
	struct task_struct *c;



	if (printk_ratelimit())

		dump_header(gfp_mask, order, mem);

		dump_header(p, gfp_mask, order, mem);



	/*

	 * If the task is already exiting, don't alarm the sysadmin or kill
@@ -576,7 +577,7 @@ static void __out_of_memory(gfp_t gfp_mask, int order) 
	/* Found nothing?!?! Either we hang forever, or we panic. */

	if (!p) {

		read_unlock(&tasklist_lock);

		dump_header(gfp_mask, order, NULL);

		dump_header(NULL, gfp_mask, order, NULL);

		panic("Out of memory and no killable processes...\n");

	}
@@ -644,7 +645,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, 
		return;



	if (sysctl_panic_on_oom == 2) {

		dump_header(gfp_mask, order, NULL);

		dump_header(NULL, gfp_mask, order, NULL);

		panic("out of memory. Compulsory panic_on_oom is selected.\n");

	}
@@ -663,7 +664,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, 


	case CONSTRAINT_NONE:

		if (sysctl_panic_on_oom) {

			dump_header(gfp_mask, order, NULL);

			dump_header(NULL, gfp_mask, order, NULL);

			panic("out of memory. panic_on_oom is selected\n");

		}

		/* Fall-through */