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=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 A2E57C4646D for ; Mon, 6 Aug 2018 20:41:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F8B521A5B for ; Mon, 6 Aug 2018 20:41:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F8B521A5B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733098AbeHFWwO (ORCPT ); Mon, 6 Aug 2018 18:52:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:41402 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731432AbeHFWwO (ORCPT ); Mon, 6 Aug 2018 18:52:14 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CC5ADADBE; Mon, 6 Aug 2018 20:41:26 +0000 (UTC) Date: Mon, 6 Aug 2018 22:41:19 +0200 From: Michal Hocko To: Yang Shi Cc: willy@infradead.org, ldufour@linux.vnet.ibm.com, kirill@shutemov.name, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC v6 PATCH 2/2] mm: mmap: zap pages with read mmap_sem in munmap Message-ID: <20180806204119.GL10003@dhcp22.suse.cz> References: <1532628614-111702-1-git-send-email-yang.shi@linux.alibaba.com> <1532628614-111702-3-git-send-email-yang.shi@linux.alibaba.com> <20180803090759.GI27245@dhcp22.suse.cz> <20180806094005.GG19540@dhcp22.suse.cz> <76c0fc2b-fca7-9f22-214a-920ee2537898@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <76c0fc2b-fca7-9f22-214a-920ee2537898@linux.alibaba.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 06-08-18 09:46:30, Yang Shi wrote: > > > On 8/6/18 2:40 AM, Michal Hocko wrote: > > On Fri 03-08-18 14:01:58, Yang Shi wrote: > > > > > > On 8/3/18 2:07 AM, Michal Hocko wrote: > > > > On Fri 27-07-18 02:10:14, Yang Shi wrote: [...] > > > > > If the vma has VM_LOCKED | VM_HUGETLB | VM_PFNMAP or uprobe, they are > > > > > considered as special mappings. They will be dealt with before zapping > > > > > pages with write mmap_sem held. Basically, just update vm_flags. > > > > Well, I think it would be safer to simply fallback to the current > > > > implementation with these mappings and deal with them on top. This would > > > > make potential issues easier to bisect and partial reverts as well. > > > Do you mean just call do_munmap()? It sounds ok. Although we may waste some > > > cycles to repeat what has done, it sounds not too bad since those special > > > mappings should be not very common. > > VM_HUGETLB is quite spread. Especially for DB workloads. > > Wait a minute. In this way, it sounds we go back to my old implementation > with special handling for those mappings with write mmap_sem held, right? Yes, I would really start simple and add further enhacements on top. -- Michal Hocko SUSE Labs