Re: [PATCH 1/6] proc, oom: drop bogus task_lock and mm check

[Oleg Nesterov]

On 05/31, Michal Hocko wrote:
>
> Oleg has pointed out that can simplify both oom_adj_write and
> oom_score_adj_write even further and drop the sighand lock. The only
> purpose of the lock was to protect p->signal from going away but this
> will not happen since ea6d290ca34c ("signals: make task_struct->signal
> immutable/refcountable").

Sorry for confusion, I meant oom_adj_read() and oom_score_adj_read().

As for oom_adj_write/oom_score_adj_write we can remove it too, but then
we need to ensure (say, using cmpxchg) that unpriviliged user can not
not decrease signal->oom_score_adj_min if its oom_score_adj_write()
races with someone else (say, admin) which tries to increase the same
oom_score_adj_min.

If you think this is not a problem - I am fine with this change. But
please also update oom_adj_read/oom_score_adj_read ;)

Oleg.