linux-kernel - [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill

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Message-ID: <20150930182405.GA15238@redhat.com>
Date:	Wed, 30 Sep 2015 20:24:05 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Rientjes <rientjes@...gle.com>,
	Kyle Walker <kwalker@...hat.com>,
	Michal Hocko <mhocko@...nel.org>,
	Stanislav Kozina <skozina@...hat.com>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	linux-kernel@...r.kernel.org
Subject: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong
	fatal_signal_pending() check in oom_kill_process()

The fatal_signal_pending() was added to suppress unnecessary "sharing
same memory" message, but it can't 100% help anyway because it can be
false-negative; SIGKILL can be already dequeued.

And worse, it can be false-positive due to exec or coredump. exec is
mostly fine, but coredump is not. It is possible that the group leader
has the pending SIGKILL because its sub-thread originated the coredump,
in this case we must not skip this process.

We could probably add the additional ->group_exit_task check but this
pach just removes the wrong check along with pr_info().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 mm/oom_kill.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4766e25..b6b8c78 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -588,11 +588,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
 		    !(p->flags & PF_KTHREAD)) {
 			if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
 				continue;
-			if (fatal_signal_pending(p))
-				continue;
 
-			pr_info("Kill process %d (%s) sharing same memory\n",
-				task_pid_nr(p), p->comm);
 			do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
 		}
 	rcu_read_unlock();
-- 
2.4.3

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