Re: [PATCH 1/3] fix the racy usage of ->signal inaccount_group_xxx/run_posix_cpu_timers

[Ingo Molnar]

* Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> Another stupid patch for 2.6.28 until we find the good fix.
> 
> Contrary to ad474caca3e2a0550b7ce0706527ad5ab389a4d4 changelog, 
> other acct_group_xxx() helpers can be called after exit_notify() by 
> timer tick. Thanks to Roland for pointing out this. Somehow I missed 
> this simple fact when I read the original patch, and I am afraid I 
> confused Frank during the discussion. Sorry.
> 
> Fortunately, these helpers work with current, we can check 
> ->exit_state to ensure that ->signal can't go away under us.
> 
> Also, add the comment and compiler barrier to 
> account_group_exec_runtime(), to make sure we load ->signal only 
> once.
> 
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

applied to tip/sched/urgent, thanks Oleg.

	Ingo
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