Messages in this thread | | | Date | Thu, 27 Mar 2014 11:35:09 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH] cgroup: missing rcu read lock around task_css_set |
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On 03/04/2014 07:57 PM, Li Zefan wrote: > On 2014/3/5 3:47, Tejun Heo wrote: >> On Tue, Mar 04, 2014 at 12:20:45PM -0500, Sasha Levin wrote: >>>> Hrm... there is a PF_EXITING check there already: >>>> >>>> #define task_css_set_check(task, __c) \ >>>> rcu_dereference_check((task)->cgroups, \ >>>> lockdep_is_held(&cgroup_mutex) || \ >>>> lockdep_is_held(&css_set_rwsem) || \ >>>> ((task)->flags & PF_EXITING) || (__c)) >>>> >>>> I see it's not happening on Linus's master so I'll run a bisection to figure out what broke it. >>> >>> Hi Tejun, >>> >>> It bisects down to your patch: "cgroup: drop task_lock() protection >>> around task->cgroups". I'll look into it later unless it's obvious >>> to you. >> >> Hmmm... maybe I'm confused and PF_EXITING is not set there and >> task_lock was what held off the lockdep warning. Confused.... >> > > Because this cgroup_exit() is called in a failure path in copy_process().
It seems there was no conclusion here and it still happens in -next, anything we can do about it?
Thanks, Sasha
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