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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 87B21C352A3 for ; Tue, 11 Feb 2020 12:31:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4BE9A20842 for ; Tue, 11 Feb 2020 12:31:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NOxUvXET" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4BE9A20842 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E394E6B02C4; Tue, 11 Feb 2020 07:31:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DEA016B02C5; Tue, 11 Feb 2020 07:31:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFF496B02C6; Tue, 11 Feb 2020 07:31:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0215.hostedemail.com [216.40.44.215]) by kanga.kvack.org (Postfix) with ESMTP id B5F376B02C4 for ; Tue, 11 Feb 2020 07:31:48 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 5F5648248047 for ; Tue, 11 Feb 2020 12:31:48 +0000 (UTC) X-FDA: 76477782696.29.song50_2cd191e7c923a X-HE-Tag: song50_2cd191e7c923a X-Filterd-Recvd-Size: 2944 Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Tue, 11 Feb 2020 12:31:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=d8hdSd/7aIqAefDk077COrSiAbGuHv2/hZDaRbUHx5o=; b=NOxUvXETeTx1yz6UwjTSSunpNI kwvGGa78MbKRfwe/RFXQkj5DgLnQ/ApsOAdtNBUr67aLVxLnyqO8L3vXrp9AH0N/sxNR1Br6lWBxY NkuQOO0h90BocBVdUBYcnRlAq4YnwGox6zB9KMwxDGVSKljAjDwobsR77xYYo04u22sN3I+7hOexb BOzNK/tzrzDDX+WbI9ccFvw+wxtEe1+N/rrflhgIPjgq4/A6WPXtkur5fkLMclSWtA0QieFCY90g5 O7rsCI3T0AjeXe8zsRlzfDwPAeInZE2UVgK6hCh1CZJDxRCFYNYParzljOehktB8K4+XY+PR5NHnm T+SO/evQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1UhZ-00035s-V3; Tue, 11 Feb 2020 12:31:42 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6C18B300739; Tue, 11 Feb 2020 13:29:49 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1F9F62B88D73B; Tue, 11 Feb 2020 13:31:38 +0100 (CET) Date: Tue, 11 Feb 2020 13:31:38 +0100 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/3] locking/mutex: Add mutex_timed_lock() to solve potential deadlock problems Message-ID: <20200211123138.GN14914@hirez.programming.kicks-ass.net> References: <20200210204651.21674-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200210204651.21674-1-longman@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Feb 10, 2020 at 03:46:48PM -0500, Waiman Long wrote: > An alternative solution proposed by this patchset is to add a new > mutex_timed_lock() call that allows an additional timeout argument. This > function will return an error code if timeout happens. The use of this > new API will prevent deadlock from happening while allowing the task > to wait a sufficient period of time before giving up. We've always rejected timed_lock implementation because, as akpm has already expressed, their need is disgusting.