From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 4E1966B000A for ; Mon, 26 Mar 2018 10:55:09 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id w10so10325645wrg.15 for ; Mon, 26 Mar 2018 07:55:09 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id e131si10152887wmg.242.2018.03.26.07.55.08 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 26 Mar 2018 07:55:08 -0700 (PDT) Date: Mon, 26 Mar 2018 16:55:05 +0200 From: Michal Hocko 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: Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: Yang Shi , Matthew Wilcox , adobriyan@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, 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