Re: [patch] mm, oom: remove task_lock protecting comm printing

Johannes Weiner
2015-09-24T19:45:39Z

On Tue, Sep 22, 2015 at 04:30:13PM -0700, David Rientjes wrote:
> The oom killer takes task_lock() in a couple of places solely to protect
> printing the task's comm.
>
> A process's comm, including current's comm, may change due to
> /proc/pid/comm or PR_SET_NAME.
>
> The comm will always be NULL-terminated, so the worst race scenario would
> only be during update. We can tolerate a comm being printed that is in
> the middle of an update to avoid taking the lock.
>
> Other locations in the kernel have already dropped task_lock() when
> printing comm, so this is consistent.
>
> Suggested-by: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: David Rientjes <rientjes@google.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>