Messages in this thread | | | Date | Fri, 14 Feb 2014 11:50:19 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH cgroup/for-3.14-fixes] cgroup: update cgroup_enable_task_cg_lists() to grab siglock |
| |
Hello,
On Fri, Feb 14, 2014 at 11:49:42AM +0800, Li Zefan wrote: > Now the only race I see is caused by checking tsk->cg_list without locking > in cgroup_exit():
Yeah, that's the one I was trying to fix.
> Your patch can fix this race, but after diving into the code I don't think > the race exists, because exit_mm() locks&unlocks task_lock, and exit_mm() > is called after exit_signal() and before cgroup_exit(), and task_lock is > also taken by cgroup_enable_task_cg_lists().
Ah, okay, so there's a task_lock somewhere in the exit path. Extremely fragile, but not broken.
> I totally agree the code is fragile and we should take your patch. I just > want to make it clear if the bug exists in real life or not, and then we > can write better changelog and decide to queue the patch for 3.14 or 3.15 > and decide to mark it for stable or not.
Yeap, no reason to mark it for -stable if it doesn't actually happen. I'll update the description and respin it for for-3.15.
Thanks!
-- tejun
| |