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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D76CFC433F5 for ; Wed, 25 May 2022 10:09:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4634E8D0003; Wed, 25 May 2022 06:09:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 412948D0002; Wed, 25 May 2022 06:09:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3234F8D0003; Wed, 25 May 2022 06:09:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 227538D0002 for ; Wed, 25 May 2022 06:09:22 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id E118F2112A for ; Wed, 25 May 2022 10:09:21 +0000 (UTC) X-FDA: 79503842922.21.B07AF2C Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf13.hostedemail.com (Postfix) with ESMTP id 897F320026 for ; Wed, 25 May 2022 10:08:53 +0000 (UTC) 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 BFD651F905; Wed, 25 May 2022 10:09:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1653473359; 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=Yo7FzjtiZvDRd+DFH4BFUlGj/8Afe054Q8uURtbD0/M=; b=yU1ERtijKkn5EuG/gZIGlqcfJroUdwuBP/DWW24Q8bFamTS94hSBnyf2otDMBLWttde2p1 sikqfxNe9h/t5OU0uA3UXUkY+/gfGLipuXHizn9i2MpapG92QawYl8T1ATFrUoe08Q74i1 g68K3irHsjIr4UEDL89hzQtFupVtWvE= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1653473359; 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=Yo7FzjtiZvDRd+DFH4BFUlGj/8Afe054Q8uURtbD0/M=; b=9UlVVBrNvELvqaYdmefU30TxErcxGeb/i0zJI+CI5pqSa0GNnANIJE37ZMNNFFfAvWamqK lLPCFJ12a1J33lDQ== 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 9DD3413487; Wed, 25 May 2022 10:09:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id q0z1JU8AjmJgZwAAMHmgww (envelope-from ); Wed, 25 May 2022 10:09:19 +0000 Message-ID: <970bbb88-3fc7-d2b9-6bb5-9c315888a889@suse.cz> Date: Wed, 25 May 2022 12:09:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v2] mm: slab: optimize memcg_slab_free_hook() Content-Language: en-US To: Muchun Song Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, smuchun@gmail.com References: <20220429123044.37885-1-songmuchun@bytedance.com> <86fdbde5-a010-9473-2f5d-807c86620509@suse.cz> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=yU1ERtij; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=9UlVVBrN; dmarc=none; spf=pass (imf13.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 897F320026 X-Stat-Signature: r1xmxxjca5ci9mbr5w93m7tpfpncq7cn X-HE-Tag: 1653473333-348746 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 5/25/22 11:15, Muchun Song wrote: > On Wed, May 25, 2022 at 09:34:58AM +0200, Vlastimil Babka wrote: >> On 5/25/22 04:18, Muchun Song wrote: >> > On Tue, May 24, 2022 at 07:05:31PM +0200, Vlastimil Babka wrote: >> >> On 4/29/22 14:30, Muchun Song wrote: >> >> > Most callers of memcg_slab_free_hook() already know the slab, which could >> >> > be passed to memcg_slab_free_hook() directly to reduce the overhead of an >> >> > another call of virt_to_slab(). For bulk freeing of objects, the call of >> >> > slab_objcgs() in the loop in memcg_slab_free_hook() is redundant as well. >> >> > Rework memcg_slab_free_hook() and build_detached_freelist() to reduce >> >> > those unnecessary overhead and make memcg_slab_free_hook() can handle bulk >> >> > freeing in slab_free(). >> >> > >> >> > Move the calling site of memcg_slab_free_hook() from do_slab_free() to >> >> > slab_free() for slub to make the code clearer since the logic is weird >> >> > (e.g. the caller need to judge whether it needs to call >> >> > memcg_slab_free_hook()). It is easy to make mistakes like missing calling >> >> > of memcg_slab_free_hook() like fixes of: >> >> > >> >> > commit d1b2cf6cb84a ("mm: memcg/slab: uncharge during kmem_cache_free_bulk()") >> >> > commit ae085d7f9365 ("mm: kfence: fix missing objcg housekeeping for SLAB") >> >> >> >> Hm is this commit also fixing such bug? in mm/slab.c __cache_free(): >> >> > > Sorry, I think I have misread it and misled you here. I mean commit My bad, I should have said "this patch" referring to yours, not "this commit" which could refer to ae085d7f9365. > ae085d7f9365 ("mm: kfence: fix missing objcg housekeeping for SLAB") > is a bug fix, this commit does not fix any issue since __cache_free() > will be called from qlink_free() and __cache_free() will call > memcg_slab_free_hook(), so there is no issues. This commit is totally > an improvements for memcg_slab_free_hook(). Ah, I see, indeed. The un-quarantining in kasan went through memcg_slab_free_hook() before your patch. But yeah it's better to do it earlier as the freed object's user is who charged it to the memcg, and is no longer using it - no reason to keep it accounted while in kasan's quarantine.