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=-2.3 required=3.0 tests=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 30EFEC49ED7 for ; Mon, 16 Sep 2019 13:53:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1FCE214AF for ; Mon, 16 Sep 2019 13:53:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387944AbfIPNxp (ORCPT ); Mon, 16 Sep 2019 09:53:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59146 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387682AbfIPNxp (ORCPT ); Mon, 16 Sep 2019 09:53:45 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B486318C4276; Mon, 16 Sep 2019 13:53:44 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-160.bos.redhat.com [10.18.17.160]) by smtp.corp.redhat.com (Postfix) with ESMTP id A5DA617F85; Mon, 16 Sep 2019 13:53:43 +0000 (UTC) Subject: Re: [PATCH 5/5] hugetlbfs: Limit wait time when trying to share huge PMD To: Matthew Wilcox , Mike Kravetz , Peter Zijlstra , Ingo Molnar , Will Deacon , Alexander Viro , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20190911150537.19527-1-longman@redhat.com> <20190911150537.19527-6-longman@redhat.com> <20190912034143.GJ29434@bombadil.infradead.org> <20190912044002.xp3c7jbpbmq4dbz6@linux-p48b> From: Waiman Long Organization: Red Hat Message-ID: Date: Mon, 16 Sep 2019 09:53:43 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190912044002.xp3c7jbpbmq4dbz6@linux-p48b> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.62]); Mon, 16 Sep 2019 13:53:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/12/19 12:40 AM, Davidlohr Bueso wrote: > > I also think that the right solution is within the mm instead of adding > a new api to rwsem and the extra complexity/overhead to osq _just_ for > this > case. We've managed to not need timeout extensions in our locking > primitives > thus far, which is a good thing imo. Adding a variant with timeout can be useful in resolving some potential deadlock issues found by lockdep. Anyway, there were talk about merging rt-mutex and regular mutex in the LPC last week. So we will need to have mutex_lock() variant with timeout for that to happen. Cheers, Longman