signal: oom_kill_task: use SEND_SIG_FORCED instead of force_sig()

oleg-nesterov · torvalds · commit d2d393099de2 · 2012-03-23T16:58:41.000-07:00
Change oom_kill_task() to use do_send_sig_info(SEND_SIG_FORCED) instead
of force_sig(SIGKILL).  With the recent changes we do not need force_ to
kill the CLONE_NEWPID tasks.

And this is more correct.  force_sig() can race with the exiting thread
even if oom_kill_task() checks p-&gt;mm != NULL, while
do_send_sig_info(group =&gt; true) kille the whole process.

Signed-off-by: Oleg Nesterov &lt;oleg@redhat.com&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Anton Vorontsov &lt;anton.vorontsov@linaro.org&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: KOSAKI Motohiro &lt;kosaki.motohiro@gmail.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
@@ -521,11 +521,11 @@ static void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 			pr_err("Kill process %d (%s) sharing same memory\n",
 				task_pid_nr(p), p->comm);
 			task_unlock(p);
-			force_sig(SIGKILL, p);
+			do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
 		}
 
 	set_tsk_thread_flag(victim, TIF_MEMDIE);
-	force_sig(SIGKILL, victim);
+	do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
 }
 #undef K
 

Original file line number	Diff line number	Diff line change
`@@ -521,11 +521,11 @@ static void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,`
`521`	`521`	`pr_err("Kill process %d (%s) sharing same memory\n",`
`522`	`522`	`task_pid_nr(p), p->comm);`
`523`	`523`	`task_unlock(p);`
`524`		`- force_sig(SIGKILL, p);`
	`524`	`+ do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);`
`525`	`525`	`}`
`526`	`526`
`527`	`527`	`set_tsk_thread_flag(victim, TIF_MEMDIE);`
`528`		`- force_sig(SIGKILL, victim);`
	`528`	`+ do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);`
`529`	`529`	`}`
`530`	`530`	`#undef K`
`531`	`531`