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 661AA6B0003 for ; Wed, 31 Jan 2018 15:24:42 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id x188so444036wmg.2 for ; Wed, 31 Jan 2018 12:24:42 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 65si2018430wrg.439.2018.01.31.12.24.41 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 31 Jan 2018 12:24:41 -0800 (PST) Date: Wed, 31 Jan 2018 21:24:38 +0100 From: Michal Hocko Subject: Re: [LSF/MM TOPIC] few MM topics Message-ID: <20180131202438.GA21609@dhcp22.suse.cz> References: <20180124092649.GC21134@dhcp22.suse.cz> <20180131192104.GD4841@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180131192104.GD4841@magnolia> Sender: owner-linux-mm@kvack.org List-ID: To: "Darrick J. Wong" Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, Johannes Weiner , Rik van Riel On Wed 31-01-18 11:21:04, Darrick J. Wong wrote: > On Wed, Jan 24, 2018 at 10:26:49AM +0100, Michal Hocko wrote: [...] > > - I would also love to talk to some FS people and convince them to move > > away from GFP_NOFS in favor of the new scope API. I know this just > > means to send patches but the existing code is quite complex and it > > really requires somebody familiar with the specific FS to do that > > work. > > Hm, are you talking about setting PF_MEMALLOC_NOFS instead of passing > *_NOFS to allocation functions and whatnot? yes memalloc_nofs_{save,restore} > Right now XFS will set it > on any thread which has a transaction open, but that doesn't help for > fs operations that don't have transactions (e.g. reading metadata, > opening files). I suppose we could just set the flag any time someone > stumbles into the fs code from userspace, though you're right that seems > daunting. I would really love to see the code to take the nofs scope (memalloc_nofs_save) at the point where the FS "critical" section starts (from the reclaim recursion POV). This would both document the context and also limit NOFS allocations to bare minumum. -- 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