Messages in this thread | | | Date | Mon, 30 May 2016 16:49:15 +0300 | From | Vladimir Davydov <> | Subject | Re: [PATCH 1/6] proc, oom: drop bogus task_lock and mm check |
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On Mon, May 30, 2016 at 03:05:51PM +0200, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > both oom_adj_write and oom_score_adj_write are using task_lock, > check for task->mm and fail if it is NULL. This is not needed because > the oom_score_adj is per signal struct so we do not need mm at all. > The code has been introduced by 3d5992d2ac7d ("oom: add per-mm oom > disable count") but we do not do per-mm oom disable since c9f01245b6a7 > ("oom: remove oom_disable_count"). > > The task->mm check is even not correct because the current thread might > have exited but the thread group might be still alive - e.g. thread > group leader would lead that echo $VAL > /proc/pid/oom_score_adj would > always fail with EINVAL while /proc/pid/task/$other_tid/oom_score_adj > would succeed. This is unexpected at best. > > Remove the lock along with the check to fix the unexpected behavior > and also because there is not real need for the lock in the first place. > > Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
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