From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6770FC433FE for ; Thu, 18 Nov 2021 23:03:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4807561A86 for ; Thu, 18 Nov 2021 23:03:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232975AbhKRXGJ (ORCPT ); Thu, 18 Nov 2021 18:06:09 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:38778 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232816AbhKRXGF (ORCPT ); Thu, 18 Nov 2021 18:06:05 -0500 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 50AEE212CC; Thu, 18 Nov 2021 23:03:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1637276583; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0VtH5sIKi/WbgeOAmRZTPkdFqlDqVx/oup6dlz2q7k4=; b=pfs+kyZkxQ60Ms5ibpPdnY/Bqak2ru5b9+dL+GA5SIV3OqPehJbo686Pcyx0enWo4EDMa2 q5uMbShdyAcaz6Dr9gU7tugww6Ev0wiDgFGIjsD2bkNibBGSWsKb1YNcd9kuKaWbbmxIfO 1HBiOQeFd5wwHvTBRPkSzhMRkgTQ/r0= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1637276583; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0VtH5sIKi/WbgeOAmRZTPkdFqlDqVx/oup6dlz2q7k4=; b=WNWIB8ZG+nPApb7FKizK8J+ry6HYhXw2oF+q8YpT6QtuiIOBfQxv7ypCyYUip6rOF2bgM+ J/HAg+AphsRRJgAA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id ECDFA13B11; Thu, 18 Nov 2021 23:03:00 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id pvlWKqTblmGoPQAAMHmgww (envelope-from ); Thu, 18 Nov 2021 23:03:00 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit MIME-Version: 1.0 From: "NeilBrown" To: "Mel Gorman" Cc: "Michal Hocko" , "Andrew Morton" , "Thierry Reding" , "Matthew Wilcox" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Mel Gorman" Subject: Re: [PATCH] MM: discard __GFP_ATOMIC In-reply-to: <20211118132753.GB3366@techsingularity.net> References: <163712397076.13692.4727608274002939094@noble.neil.brown.name>, , <20211118132753.GB3366@techsingularity.net> Date: Fri, 19 Nov 2021 10:02:55 +1100 Message-id: <163727657594.13692.10357464624495712361@noble.neil.brown.name> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 19 Nov 2021, Mel Gorman wrote: > On Thu, Nov 18, 2021 at 10:22:36AM +0100, Michal Hocko wrote: > > [Cc Mel] > > > > I think this patch should be ok. There are few direct users of __GFP_HIGH > and some of them are borderline silly (e.g. mm/shmem.c specifying > __GFP_HIGH|__GFP_NOMEMALLOC) while others just look questionable ( > drivers/md/raid10.c seems to assume __GFP_HIGH guarantees allocation > success). Xen appears to be the worst abuser of __GFP_HIGH. That __GFP_HIGH in raid10.c is passed to mempool_alloc(), so there is no assumption that __GFP_HIGH will provide guarantees - the mempool does that. The comment - which I wrote 4 years ago and don't recall at all - suggest it was purely about performance - get error handling out of the way quickly. I doubt I could justify it if challenged... Thanks, NeilBrown > > -- > Mel Gorman > SUSE Labs > >