From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com [74.125.82.52]) by kanga.kvack.org (Postfix) with ESMTP id 0A3E26B0038 for ; Fri, 13 Nov 2015 05:18:36 -0500 (EST) Received: by wmww144 with SMTP id w144so22376214wmw.1 for ; Fri, 13 Nov 2015 02:18:35 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id k197si4601804wmg.106.2015.11.13.02.18.34 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 13 Nov 2015 02:18:35 -0800 (PST) Date: Fri, 13 Nov 2015 10:18:31 +0000 From: Mel Gorman Subject: Re: [PATCH] mm: get rid of __alloc_pages_high_priority Message-ID: <20151113101831.GF19677@suse.de> References: <1447343618-19696-1-git-send-email-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1447343618-19696-1-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org Cc: Andrew Morton , linux-mm@kvack.org, LKML , Michal Hocko On Thu, Nov 12, 2015 at 04:53:38PM +0100, mhocko@kernel.org wrote: > From: Michal Hocko > > __alloc_pages_high_priority doesn't do anything special other than it > calls get_page_from_freelist and loops around GFP_NOFAIL allocation > until it succeeds. It would be better if the first part was done in > __alloc_pages_slowpath where we modify the zonelist because this would > be easier to read and understand. And do the retry at the very same > place because retrying without even attempting to do any reclaim is > fragile because we are basically relying on somebody else to make the > reclaim (be it the direct reclaim or OOM killer) for us. The caller > might be holding resources (e.g. locks) which block other other > reclaimers from making any progress for example. > > Remove the helper and open code it into its only user. We have to be > careful about __GFP_NOFAIL allocations from the PF_MEMALLOC context > even though this is a very bad idea to begin with because no progress > can be gurateed at all. We shouldn't break the __GFP_NOFAIL semantic > here though. It could be argued that this is essentially GFP_NOWAIT > context which we do not support but PF_MEMALLOC is much harder to check > for existing users because they might happen deep down the code path > performed much later after setting the flag so we cannot really rule out > there is no kernel path triggering this combination. > > Signed-off-by: Michal Hocko Acked-by: Mel Gorman -- Mel Gorman 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