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Date:   Thu, 18 May 2023 11:42:12 -0500
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Subject: Re: [RFC PATCH 1/8] signal: Dequeue SIGKILL even if
 SIGNAL_GROUP_EXIT/group_exec_task is set
Content-Language: en-US
To:     Oleg Nesterov <oleg@redhat.com>
Cc:     "Eric W. Biederman" <ebiederm@xmission.com>, linux@leemhuis.info,
        nicolas.dichtel@6wind.com, axboe@kernel.dk,
        torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, mst@redhat.com,
        sgarzare@redhat.com, jasowang@redhat.com, stefanha@redhat.com,
        brauner@kernel.org
References: <20230518000920.191583-1-michael.christie@oracle.com>
 <20230518000920.191583-2-michael.christie@oracle.com>
 <87ednei9is.fsf@email.froward.int.ebiederm.org>
 <ab7d07ba-5dc3-95c0-aa7c-c2575d03f429@oracle.com>
 <20230518162508.GB20779@redhat.com>
From:   Mike Christie <michael.christie@oracle.com>
In-Reply-To: <20230518162508.GB20779@redhat.com>
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On 5/18/23 11:25 AM, Oleg Nesterov wrote:
> I too do not understand the 1st change in this patch ...
> 
> On 05/18, Mike Christie wrote:
>>
>> In the other patches we do:
>>
>> if (get_signal(ksig))
>> 	start_exit_cleanup_by_stopping_newIO()
>> 	flush running IO()
>> 	exit()
>>
>> But to do the flush running IO() part of this I need to wait for it so
>> that's why I wanted to be able to dequeue the SIGKILL and clear the
>> TIF_SIGPENDING bit.
> 
> But get_signal() will do what you need, dequeue SIGKILL and clear SIGPENDING ?
> 
> 	if ((signal->flags & SIGNAL_GROUP_EXIT) ||
> 	     signal->group_exec_task) {
> 		clear_siginfo(&ksig->info);
> 		ksig->info.si_signo = signr = SIGKILL;
> 		sigdelset(&current->pending.signal, SIGKILL);
> 
> this "dequeues" SIGKILL,
> 
> 		trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
> 			&sighand->action[SIGKILL - 1]);
> 		recalc_sigpending();
> 
> this clears TIF_SIGPENDING.
> 

I see what you guys meant. TIF_SIGPENDING isn't getting cleared.
I'll dig into why.