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signals: introduce send_sigkill() helper

Oleg Nesterov linux-mm lkml 1 version In review

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  1. v1 Latest1 patch 4 repliesIn review

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1/1signals: introduce send_sigkill() helperinclude/linux/sched.h kernel/pid_namespace.c+10 -74 replies

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PatchKAMEZAWA HiroyukiKOSAKI Motohiro
1/1R-b R-b

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Cover letter [PATCH 0/1] signals: introduce send_sigkill() helper
Quoted 15 lines · Oleg Nesterov

Review static int __oom_kill_process(struct task_struct *p, struct mem_cgroup *mem) · line 402

Quoted 7 lines
(quoted diff) +1 -1
@@ -399,7 +399,7 @@ static int __oom_kill_process(struct task_struct *p, struct mem_cgroup *mem)
 	p->rt.time_slice = HZ;
 	set_tsk_thread_flag(p, TIF_MEMDIE);
 
-	force_sig(SIGKILL, p);
+	send_sig(SIGKILL, p, 1);

This is not right, we need send_sig(SIGKILL, p, 0). Better yet, send_sig_info(SIGKILL, SEND_SIG_NOINFO). I think send_sig() should die.

The reason is that si_fromuser() must be true, otherwise we can't kill the SIGNAL_UNKILLABLE (sub-namespace inits) tasks.

Quoted 7 lines

Oh. This reminds me, we really need the trivial (but annoying) cleanups here. The usage of SEND_SIG_ constants is messy, and they should be renamed at least.

And in fact, we need the new one which acts like SEND_SIG_FORCED but si_fromuser(). We do not want to allocate the memory when the caller is oom_kill or zap_pid_ns_processes().

I tried to make some simple cleanups right now, but this really needs time and discussion.

So. If we are going to remove force_sig() in mm/oom_kill.c (and I think we should), I'd like to add the trivial helper first.

Oleg.

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