From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 014AA6B0005 for ; Wed, 31 Jan 2018 03:01:17 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id 17so3541421wma.1 for ; Wed, 31 Jan 2018 00:01:16 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id y8si10610656wmc.74.2018.01.31.00.01.15 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 31 Jan 2018 00:01:15 -0800 (PST) Date: Wed, 31 Jan 2018 09:01:14 +0100 From: Michal Hocko Subject: Re: [PATCH] Lock mmap_sem when calling migrate_pages() in do_move_pages_to_node() Message-ID: <20180131080114.GM21609@dhcp22.suse.cz> References: <20180130030011.4310-1-zi.yan@sent.com> <20180130081415.GO21609@dhcp22.suse.cz> <5A7094DA.4000804@cs.rutgers.edu> <20180130161025.GH21609@dhcp22.suse.cz> 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: Zi Yan Cc: Andrew Morton , "Kirill A . Shutemov" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hugh Dickins On Tue 30-01-18 14:12:28, Zi Yan wrote: > On 30 Jan 2018, at 11:10, Michal Hocko wrote: [...] > I think the question is whether we need to hold mmap_sem for > migrate_pages(). Hugh also agrees it is not necessary on a separate > email. But it is held in the original code. I would be really surprised if we really needed the lock. If we do, however, then we really need a very good explanation why. The code used to do so is not a valid reason. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org