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Date: Thu, 26 Nov 2009 09:11:17 +0900
From: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
stable <stable@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
linux-mm <linux-mm@...ck.org>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
David Rientjes <rientjes@...gle.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Subject: [BUGFIX][PATCH v2 -mmotm] memcg: avoid oom-killing innocent task in
case of use_hierarchy
On Wed, 25 Nov 2009 12:45:51 -0800, Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Wed, 25 Nov 2009 14:32:18 +0900
> Daisuke Nishimura <nishimura@....nes.nec.co.jp> wrote:
>
> > > Hmm. Maybe not-expected behavior...could you add comment ?
> > >
> > How about this ?
> >
> > > Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> > > (*) I'm sorry I can't work enough in these days.
> > >
> >
> > BTW, this patch conflict with oom-dump-stack-and-vm-state-when-oom-killer-panics.patch
> > in current mmotm(that's why I post mmotm version separately), so this bug will not be fixed
> > till 2.6.33 in linus-tree.
> > So I think this patch should go in 2.6.32.y too.
>
> I don't actually have a 2.6.33 version of this patch yet.
I add comments as I did in for-stable version and attach the updated patch
for-mmotm to this mail.
It can be applied on current mmotm(2009-11-24-16-47).
===
From: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
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@....nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@...ux.vnet.ibm.com>
---
mm/memcontrol.c | 10 ++++++++--
mm/oom_kill.c | 13 +++++++------
2 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 661b8c6..951c103 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -759,7 +759,13 @@ 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);
@@ -1008,7 +1014,7 @@ 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;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index ab04537..be56461 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -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 */
--
1.5.6.1
--
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