[PATCH] proc_oom_score: remove tasklist_lock and pid_alive()

From	Oleg Nesterov <oleg@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH] proc_oom_score: remove tasklist_lock and pid_alive()
Date	2016-06-08 23:20 +0200
Message-ID	<rHT3k-5qw-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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This was needed before to ensure that ->signal != 0 and do_each_thread()
is safe, see the commit b95c35e76b29b for details.

Today tsk->signal can't go away and for_each_thread(tsk) is always safe.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 fs/proc/base.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index a11eb71..93e7754 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -579,11 +579,8 @@ static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
 	unsigned long totalpages = totalram_pages + total_swap_pages;
 	unsigned long points = 0;
 
-	read_lock(&tasklist_lock);
-	if (pid_alive(task))
-		points = oom_badness(task, NULL, NULL, totalpages) *
-						1000 / totalpages;
-	read_unlock(&tasklist_lock);
+	points = oom_badness(task, NULL, NULL, totalpages) *
+					1000 / totalpages;
 	seq_printf(m, "%lu\n", points);
 
 	return 0;
-- 
2.5.0

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[PATCH] proc_oom_score: remove tasklist_lock and pid_alive() Oleg Nesterov <oleg@redhat.com> - 2016-06-08 23:20 +0200
  Re: [PATCH] proc_oom_score: remove tasklist_lock and pid_alive() David Rientjes <rientjes@google.com> - 2016-06-09 00:50 +0200
  Re: [PATCH] proc_oom_score: remove tasklist_lock and pid_alive() Michal Hocko <mhocko@kernel.org> - 2016-06-09 08:50 +0200

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