Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933784AbdDELjW (ORCPT ); Wed, 5 Apr 2017 07:39:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:51634 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933452AbdDELjT (ORCPT ); Wed, 5 Apr 2017 07:39:19 -0400 Subject: Re: [PATCH 4/4] mtd: nand: nandsim: convert to memalloc_noreclaim_*() To: Richard Weinberger , Michal Hocko References: <20170405074700.29871-1-vbabka@suse.cz> <20170405074700.29871-5-vbabka@suse.cz> <20170405113157.GM6035@dhcp22.suse.cz> Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Johannes Weiner , linux-block@vger.kernel.org, nbd-general@lists.sourceforge.net, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, netdev@vger.kernel.org, Boris Brezillon , Adrian Hunter From: Vlastimil Babka Message-ID: <9b9d5bca-e125-e07b-b700-196cc800bbd7@suse.cz> Date: Wed, 5 Apr 2017 13:39:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 925 Lines: 24 On 04/05/2017 01:36 PM, Richard Weinberger wrote: > Michal, > > Am 05.04.2017 um 13:31 schrieb Michal Hocko: >> On Wed 05-04-17 09:47:00, Vlastimil Babka wrote: >>> Nandsim has own functions set_memalloc() and clear_memalloc() for robust >>> setting and clearing of PF_MEMALLOC. Replace them by the new generic helpers. >>> No functional change. >> >> This one smells like an abuser. Why the hell should read/write path >> touch memory reserves at all! > > Could be. Let's ask Adrian, AFAIK he wrote that code. > Adrian, can you please clarify why nandsim needs to play with PF_MEMALLOC? I was thinking about it and concluded that since the simulator can be used as a block device where reclaimed pages go to, writing the data out is a memalloc operation. Then reading can be called as part of r-m-w cycle, so reading as well. But it would be great if somebody more knowledgeable confirmed this. > Thanks, > //richard >