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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 031A1C6FD18 for ; Wed, 29 Mar 2023 08:42:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229959AbjC2ImC (ORCPT ); Wed, 29 Mar 2023 04:42:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230450AbjC2Il6 (ORCPT ); Wed, 29 Mar 2023 04:41:58 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45CDD1BB for ; Wed, 29 Mar 2023 01:41:54 -0700 (PDT) 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-out2.suse.de (Postfix) with ESMTPS id CAC831FDF3; Wed, 29 Mar 2023 08:41:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1680079312; 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=FXNeQEeNkO9Z+oDPQiH/Ygm1gn1aQwVSYkquaLAzwlA=; b=LUVj+4KeuB2yvYNm15M0kJNlEkkTHl61wObJ0NeETKr2EQ8596eyWXIxI0wWssy36Q+LwV FRcYMZVTghWFqYMql9w+AXL4wZZ9guThsu4rznrzpyhXSs/rUXyQ9iGYQUF+QT6N5CSk9F iJyQzPwcSTv99ZZY0QB+ZMvvfysZXis= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1680079312; 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=FXNeQEeNkO9Z+oDPQiH/Ygm1gn1aQwVSYkquaLAzwlA=; b=b8+5k1cjnJfonOpuSjz3VtwXV2d48GqUcCFYzjm/8FadUQaKJktk8tbfJ4nlPyFi14BOGR gngJBpU/t+aqd0Dg== 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 9293E139D3; Wed, 29 Mar 2023 08:41:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id KV4GItD5I2RjagAAMHmgww (envelope-from ); Wed, 29 Mar 2023 08:41:52 +0000 Message-ID: <4f1096f0-cb6e-7cd2-5f41-c5e4b53fa407@suse.cz> Date: Wed, 29 Mar 2023 10:41:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH] mm/slub: Reduce memory consumption in extreme scenarios Content-Language: en-US To: "chenjun (AM)" , Mike Rapoport Cc: "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "cl@linux.com" , "penberg@kernel.org" , "rientjes@google.com" , "iamjoonsoo.kim@lge.com" , "akpm@linux-foundation.org" , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "xuqiang (M)" , "Wangkefeng (OS Kernel Lab)" , Michal Hocko , Mel Gorman References: <20230314123403.100158-1-chenjun102@huawei.com> <0cad1ff3-8339-a3eb-fc36-c8bda1392451@suse.cz> <344c7521d72e4107b451c19b329e9864@huawei.com> <8c700468-245d-72e9-99e7-b99d4547e6d8@suse.cz> <015855b3-ced3-8d84-e21d-cc6ce112b556@suse.cz> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/21/23 10:30, chenjun (AM) wrote: > 在 2023/3/20 17:12, Mike Rapoport 写道: >>>> >>>> If we ignore __GFP_ZERO passed by kzalloc， kzalloc will not work. >>>> Could we just unmask __GFP_RECLAIMABLE | __GFP_RECLAIM? >>>> >>>> pc.flags &= ~(__GFP_RECLAIMABLE | __GFP_RECLAIM) >>>> pc.flags |= __GFP_THISNODE >>> >>> __GFP_RECLAIMABLE would be wrong, but also ignored as new_slab() does: >>> flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK) >>> >>> which would filter out __GFP_ZERO as well. That's not a problem as kzalloc() >>> will zero out the individual allocated objects, so it doesn't matter if we >>> don't zero out the whole slab page. >>> >>> But I wonder, if we're not past due time for a helper e.g. >>> gfp_opportunistic(flags) that would turn any allocation flags to a >>> GFP_NOWAIT while keeping the rest of relevant flags intact, and thus there >>> would be one canonical way to do it - I'm sure there's a number of places >>> with their own variants now? >>> With such helper we'd just add __GFP_THISNODE to the result here as that's >>> specific to this particular opportunistic allocation. >> >> I like the idea, but maybe gfp_no_reclaim() would be clearer? >> > > #define gfp_no_reclaim(gfpflag) (gfpflag & ~__GFP_DIRECT_RECLAIM) I hoped for more feedback on the idea, but it's probably best proposed outside of this slub-specific thread, so we could go for an open-coded solution in slub for now. Also just masking out __GFP_DIRECT_RECLAIM wouldn't be sufficient in any case for the general solution/ > And here, > > pc.flags = gfp_no_reclaim(gfpflags) | __GFP_THISNODE. I'd still suggest as earlier: pc.flags = GFP_NOWAIT | __GFP_NOWARN |__GFP_THISNODE; > Do I get it right？