From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5027FC7618B for ; Mon, 29 Jul 2019 08:13:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EEAE20644 for ; Mon, 29 Jul 2019 08:13:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727516AbfG2INK (ORCPT ); Mon, 29 Jul 2019 04:13:10 -0400 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:34916 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726690AbfG2INJ (ORCPT ); Mon, 29 Jul 2019 04:13:09 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=kerneljasonxing@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0TY1HZl2_1564387964; Received: from ali-6c96cfdd2b5d.local(mailfrom:kerneljasonxing@linux.alibaba.com fp:SMTPD_---0TY1HZl2_1564387964) by smtp.aliyun-inc.com(127.0.0.1); Mon, 29 Jul 2019 16:13:03 +0800 Subject: Re: [PATCH] psi: get poll_work to run when calling poll syscall next time To: hannes@cmpxchg.org, surenb@google.com, mingo@redhat.com, peterz@infradead.org Cc: dennis@kernel.org, axboe@kernel.dk, lizefan@huawei.com, tj@kernel.org, linux-kernel@vger.kernel.org References: <1563864339-2621-1-git-send-email-kerneljasonxing@linux.alibaba.com> From: Jason Xing Message-ID: <4d7ca842-3246-10ee-9ae2-973d1b88ed93@linux.alibaba.com> Date: Mon, 29 Jul 2019 16:12:44 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1563864339-2621-1-git-send-email-kerneljasonxing@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Could someone take a quick look at this patch? It's not complicated at all, just one line added into PSI which can make the poll() run in the right way. Thanks, Jason On 2019/7/23 下午2:45, Jason Xing wrote: > Only when calling the poll syscall the first time can user > receive POLLPRI correctly. After that, user always fails to > acquire the event signal. > > Reproduce case: > 1. Get the monitor code in Documentation/accounting/psi.txt > 2. Run it, and wait for the event triggered. > 3. Kill and restart the process. > > If the user doesn't kill the monitor process, it seems the > poll_work works fine. After killing and restarting the monitor, > the poll_work in kernel will never run again due to the wrong > value of poll_scheduled. Therefore, we should reset the value > as group_init() does after the last trigger is destroyed. > > Signed-off-by: Jason Xing > --- > kernel/sched/psi.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c > index 7acc632..66f4385 100644 > --- a/kernel/sched/psi.c > +++ b/kernel/sched/psi.c > @@ -1133,6 +1133,12 @@ static void psi_trigger_destroy(struct kref *ref) > if (kworker_to_destroy) { > kthread_cancel_delayed_work_sync(&group->poll_work); > kthread_destroy_worker(kworker_to_destroy); > + /* > + * The poll_work should have the chance to be put into the > + * kthread queue when calling poll syscall next time. So > + * reset poll_scheduled to zero as group_init() does > + */ > + atomic_set(&group->poll_scheduled, 0); > } > kfree(t); > } >