From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752277AbeCZOzJ (ORCPT ); Mon, 26 Mar 2018 10:55:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:50083 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127AbeCZOzI (ORCPT ); Mon, 26 Mar 2018 10:55:08 -0400 Date: Mon, 26 Mar 2018 16:55:05 +0200 From: Michal Hocko To: Tetsuo Handa Cc: Yang Shi , Matthew Wilcox , adobriyan@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct Message-ID: <20180326145505.GM5652@dhcp22.suse.cz> References: <1521851771-108673-1-git-send-email-yang.shi@linux.alibaba.com> <20180324043044.GA22733@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 26-03-18 23:49:18, Tetsuo Handa wrote: [...] > Also, even if we succeeded to avoid mmap_sem contention at that location, > won't we after all get mmap_sem contention messages a bit later, for > access_remote_vm() holds mmap_sem which would lead to traces like above > if mmap_sem is already contended? Yes, but at least we get rid of the mmap_sem for something that can use a more fine grained locking. Maybe we can get a finer grained range locking for mmap_sem one day and not having the full range locked section will be a plus. -- Michal Hocko SUSE Labs