From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id BC99D6B0010 for ; Wed, 11 Jul 2018 07:13:16 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id r1-v6so5767547lfi.16 for ; Wed, 11 Jul 2018 04:13:16 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id x14-v6sor4741005lfe.80.2018.07.11.04.13.15 for (Google Transport Security); Wed, 11 Jul 2018 04:13:15 -0700 (PDT) Date: Wed, 11 Jul 2018 14:13:12 +0300 From: "Kirill A. Shutemov" Subject: Re: [RFC v4 0/3] mm: zap pages with read mmap_sem in munmap for large mapping Message-ID: <20180711111311.hrh5kxdottmpdpn2@kshutemo-mobl1> References: <1531265649-93433-1-git-send-email-yang.shi@linux.alibaba.com> <20180711103312.GH20050@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180711103312.GH20050@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Yang Shi , willy@infradead.org, ldufour@linux.vnet.ibm.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Jul 11, 2018 at 12:33:12PM +0200, Michal Hocko wrote: > this is not a small change for something that could be achieved > from the userspace trivially (just call madvise before munmap - library > can hide this). Most workloads will even not care about races because > they simply do not play tricks with mmaps and userspace MM. So why do we > want to put the additional complexity into the kernel? As I said before, kernel latency issues have to be addressed in kernel. We cannot rely on userspace being kind here. -- Kirill A. Shutemov