From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH 1/3] signals: Allow generation of SIGKILL to exiting task. Date: Tue, 24 Apr 2018 11:10:42 -0500 Message-ID: <87a7tsd1q5.fsf@xmission.com> References: <1524583836-12130-1-git-send-email-andrey.grodzovsky@amd.com> <1524583836-12130-2-git-send-email-andrey.grodzovsky@amd.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1524583836-12130-2-git-send-email-andrey.grodzovsky@amd.com> (Andrey Grodzovsky's message of "Tue, 24 Apr 2018 11:30:34 -0400") Sender: linux-kernel-owner@vger.kernel.org To: Andrey Grodzovsky Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Alexander.Deucher@amd.com, Christian.Koenig@amd.com, David.Panariti@amd.com, oleg@redhat.com, akpm@linux-foundation.org List-Id: amd-gfx.lists.freedesktop.org Andrey Grodzovsky writes: > Currently calling wait_event_killable as part of exiting process > will stall forever since SIGKILL generation is suppresed by PF_EXITING. > > In our partilaur case AMDGPU driver wants to flush all GPU jobs in > flight before shutting down. But if some job hangs the pipe we still want to > be able to kill it and avoid a process in D state. This makes me profoundly uncomfotable. You are changing the linux semantics of what it means for a process to be exiting. Functionally this may require all kinds of changes to when we allow processes to stop processing signals. So without a really good thought out explanation that takes into account all of the issues involved in process exiting and posix conformance. Nacked-by: "Eric W. Biederman" Eric > Signed-off-by: Andrey Grodzovsky > --- > kernel/signal.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/signal.c b/kernel/signal.c > index c6e4c83..c49c706 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -886,10 +886,10 @@ static inline int wants_signal(int sig, struct task_struct *p) > { > if (sigismember(&p->blocked, sig)) > return 0; > - if (p->flags & PF_EXITING) > - return 0; > if (sig == SIGKILL) > return 1; > + if (p->flags & PF_EXITING) > + return 0; > if (task_is_stopped_or_traced(p)) > return 0; > return task_curr(p) || !signal_pending(p);