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* [patch added to 3.12-stable] sched: Fix race between task_group and sched_task_group
@ 2016-04-01  8:36 Jiri Slaby
  2016-04-01  8:36 ` [patch added to 3.12-stable] Btrfs: skip locking when searching commit root Jiri Slaby
                   ` (15 more replies)
  0 siblings, 16 replies; 19+ messages in thread
From: Jiri Slaby @ 2016-04-01  8:36 UTC (permalink / raw)
  To: stable
  Cc: Kirill Tkhai, Peter Zijlstra, Linus Torvalds, Ingo Molnar,
	Jiri Slaby

From: Kirill Tkhai <ktkhai@parallels.com>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.

===============

commit eeb61e53ea19be0c4015b00b2e8b3b2185436f2b upstream.

The race may happen when somebody is changing task_group of a forking task.
Child's cgroup is the same as parent's after dup_task_struct() (there just
memory copying). Also, cfs_rq and rt_rq are the same as parent's.

But if parent changes its task_group before it's called cgroup_post_fork(),
we do not reflect this situation on child. Child's cfs_rq and rt_rq remain
the same, while child's task_group changes in cgroup_post_fork().

To fix this we introduce fork() method, which calls sched_move_task() directly.
This function changes sched_task_group on appropriate (also its logic has
no problem with freshly created tasks, so we shouldn't introduce something
special; we are able just to use it).

Possibly, this decides the Burke Libbey's problem: https://lkml.org/lkml/2014/10/24/456

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 kernel/sched/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3800316d7424..7381119ec1e9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7233,6 +7233,11 @@ static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
 	sched_offline_group(tg);
 }
 
+static void cpu_cgroup_fork(struct task_struct *task)
+{
+	sched_move_task(task);
+}
+
 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
 				 struct cgroup_taskset *tset)
 {
@@ -7602,6 +7607,7 @@ struct cgroup_subsys cpu_cgroup_subsys = {
 	.css_free	= cpu_cgroup_css_free,
 	.css_online	= cpu_cgroup_css_online,
 	.css_offline	= cpu_cgroup_css_offline,
+	.fork		= cpu_cgroup_fork,
 	.can_attach	= cpu_cgroup_can_attach,
 	.attach		= cpu_cgroup_attach,
 	.exit		= cpu_cgroup_exit,
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 19+ messages in thread
end of thread, other threads:[~2016-04-01  9:41 UTC | newest]

Thread overview: 19+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-04-01  8:36 [patch added to 3.12-stable] sched: Fix race between task_group and sched_task_group Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] Btrfs: skip locking when searching commit root Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] bnx2x: Add new device ids under the Qlogic vendor Jiri Slaby
2016-04-01  8:59   ` Yuval Mintz
2016-04-01  9:41     ` Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] drivers/base/memory.c: fix kernel warning during memory hotplug on ppc64 Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] ALSA: rawmidi: Make snd_rawmidi_transmit() race-free Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] ALSA: seq: Fix leak of pool buffer at concurrent writes Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] memcg: do not hang on OOM when killed by userspace OOM access to memory reserves Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] USB: fix invalid memory access in hub_activate() Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] intel_pstate: Use del_timer_sync in intel_pstate_cpu_stop Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] KVM: SVM: add rdmsr support for AMD event registers Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] USB: visor: fix null-deref at probe Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] s390/mm: four page table levels vs. fork Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] hwmon: (coretemp) Increase limit of maximum core ID from 32 to 128 Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] perf, nmi: Fix unknown NMI warning Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] Fix kmalloc overflow in LPFC driver at large core count Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] nfs: fix high load average due to callback thread sleeping Jiri Slaby
2016-04-01  8:36 ` [patch added to 3.12-stable] net/ipv6: fix DEVCONF_ constants Jiri Slaby

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