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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 60EE1C433E1 for ; Thu, 25 Mar 2021 09:26:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19AD1619E4 for ; Thu, 25 Mar 2021 09:26:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229977AbhCYJ00 (ORCPT ); Thu, 25 Mar 2021 05:26:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:53482 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229576AbhCYJ0Q (ORCPT ); Thu, 25 Mar 2021 05:26:16 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 632A0AF65; Thu, 25 Mar 2021 09:26:14 +0000 (UTC) Date: Thu, 25 Mar 2021 10:26:13 +0100 (CET) From: Miroslav Benes To: Dong Kai cc: jpoimboe@redhat.com, jikos@kernel.org, pmladek@suse.com, joe.lawrence@redhat.com, axboe@kernel.dk, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] livepatch: klp_send_signal should treat PF_IO_WORKER like PF_KTHREAD In-Reply-To: <20210325014836.40649-1-dongkai11@huawei.com> Message-ID: References: <20210325014836.40649-1-dongkai11@huawei.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 Mar 2021, Dong Kai wrote: > commit 15b2219facad ("kernel: freezer should treat PF_IO_WORKER like > PF_KTHREAD for freezing") is to fix the freezeing issue of IO threads > by making the freezer not send them fake signals. > > Here live patching consistency model call klp_send_signals to wake up > all tasks by send fake signal to all non-kthread which only check the > PF_KTHREAD flag, so it still send signal to io threads which may lead to > freezeing issue of io threads. I suppose this could happen, but it will also affect the live patching transition if the io threads do not react to signals. Are you able to reproduce it easily? I mean, is there a testcase I could use to take a closer look? > Here we take the same fix action by treating PF_IO_WORKERS as PF_KTHREAD > within klp_send_signal function. Yes, this sounds reasonable. Miroslav > Signed-off-by: Dong Kai > --- > note: > the io threads freeze issue links: > [1] https://lore.kernel.org/io-uring/YEgnIp43%2F6kFn8GL@kevinlocke.name/ > [2] https://lore.kernel.org/io-uring/d7350ce7-17dc-75d7-611b-27ebf2cb539b@kernel.dk/ > > kernel/livepatch/transition.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c > index f6310f848f34..0e1c35c8f4b4 100644 > --- a/kernel/livepatch/transition.c > +++ b/kernel/livepatch/transition.c > @@ -358,7 +358,7 @@ static void klp_send_signals(void) > * Meanwhile the task could migrate itself and the action > * would be meaningless. It is not serious though. > */ > - if (task->flags & PF_KTHREAD) { > + if (task->flags & (PF_KTHREAD | PF_IO_WORKER)) { > /* > * Wake up a kthread which sleeps interruptedly and > * still has not been migrated.