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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 8F179C433C1 for ; Thu, 25 Mar 2021 16:44:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E47E619F8 for ; Thu, 25 Mar 2021 16:44:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229764AbhCYQng (ORCPT ); Thu, 25 Mar 2021 12:43:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:54171 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229666AbhCYQnN (ORCPT ); Thu, 25 Mar 2021 12:43:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616690592; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VXkz74om/p18FTc/ggtD/waEhXQyGXNW+IbQIQcMvEg=; b=OtSebmLD83lw6cdbxXlMxaq7e0ry1nXeBLHXaoFz0XRleHG0tAUJG4aQ7IxJ7UCbxaN6Fv aMnlg5KNhxcrqn8WWW2b6wLauRZ8EXUDHepab66HblHZc1N/6VVLH/8SKZEgpsG+7gy2pZ iDCal1J4hHh9RnNA4KBs+VOpIzKd9vM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-144-4tvlbfi4MNGohs7vQUxjag-1; Thu, 25 Mar 2021 12:43:10 -0400 X-MC-Unique: 4tvlbfi4MNGohs7vQUxjag-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5193C18C89DF; Thu, 25 Mar 2021 16:43:08 +0000 (UTC) Received: from [10.10.112.16] (ovpn-112-16.rdu2.redhat.com [10.10.112.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3159660D07; Thu, 25 Mar 2021 16:43:07 +0000 (UTC) Subject: Re: [PATCH] livepatch: klp_send_signal should treat PF_IO_WORKER like PF_KTHREAD To: Miroslav Benes , Dong Kai Cc: jpoimboe@redhat.com, jikos@kernel.org, pmladek@suse.com, axboe@kernel.dk, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210325014836.40649-1-dongkai11@huawei.com> From: Joe Lawrence Message-ID: <01cbab2f-da8b-f289-2241-d258406a4b6c@redhat.com> Date: Thu, 25 Mar 2021 12:43:06 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/25/21 5:26 AM, Miroslav Benes wrote: > 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? > If repro is only hypothetical at this point, perhaps we can artificially create it in selftests? And useful to verify the future change you mentioned in your other reply? -- Joe