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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: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daisuke Nishimura 2009-12-15 16:47:12 -08:00 committed by Linus Torvalds
parent 57f9fd7d25
commit d31f56dbf8
2 changed files with 15 additions and 8 deletions
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10
mm/memcontrol.c
View File

@ -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;

13
mm/oom_kill.c
View File

@ -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 @@ retry:
/* 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 */