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=-2.5 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 A910CC4CEC9 for ; Fri, 13 Sep 2019 18:23:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8862320830 for ; Fri, 13 Sep 2019 18:23:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388766AbfIMSXq (ORCPT ); Fri, 13 Sep 2019 14:23:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54844 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387802AbfIMSXq (ORCPT ); Fri, 13 Sep 2019 14:23:46 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 52ACE10C0515; Fri, 13 Sep 2019 18:23:46 +0000 (UTC) Received: from llong.remote.csb (ovpn-125-105.rdu2.redhat.com [10.10.125.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0C6FC5C1D4; Fri, 13 Sep 2019 18:23:44 +0000 (UTC) Subject: Re: [PATCH 5/5] hugetlbfs: Limit wait time when trying to share huge PMD To: Mike Kravetz , Peter Zijlstra , Ingo Molnar , Will Deacon , Alexander Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Davidlohr Bueso References: <20190911150537.19527-1-longman@redhat.com> <20190911150537.19527-6-longman@redhat.com> <87ac9e4f-9301-9eb7-e68b-a877e7cf0384@oracle.com> From: Waiman Long Organization: Red Hat Message-ID: <3d98ea00-ea0d-a9b1-9e1a-e78a731c20a5@redhat.com> Date: Fri, 13 Sep 2019 14:23:44 -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: <87ac9e4f-9301-9eb7-e68b-a877e7cf0384@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.65]); Fri, 13 Sep 2019 18:23:46 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 9/12/19 5:43 PM, Mike Kravetz wrote: > On 9/12/19 2:06 AM, Waiman Long wrote: >> If we can take the rwsem in read mode, that should solve the problem >> AFAICS. As I don't have a full understanding of the history of that >> code, I didn't try to do that in my patch. > Do you still have access to an environment that creates the long stalls? > If so, can you try the simple change of taking the semaphore in read mode > in huge_pmd_share. > That is what I am planning to do. I don't have an environment to reproduce the problem myself. I have to create a test kernel and ask the customer to try it out. Cheers, Longman