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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6992CCD3438 for ; Wed, 12 Nov 2025 18:46:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ADFC18E0007; Wed, 12 Nov 2025 13:46:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AB72A8E0002; Wed, 12 Nov 2025 13:46:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9F3FF8E0007; Wed, 12 Nov 2025 13:46:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 895F28E0002 for ; Wed, 12 Nov 2025 13:46:48 -0500 (EST) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 3FD4089357 for ; Wed, 12 Nov 2025 18:46:48 +0000 (UTC) X-FDA: 84102836496.15.880C9CC Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf22.hostedemail.com (Postfix) with ESMTP id D4714C0016 for ; Wed, 12 Nov 2025 18:46:46 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=R2Mov+CO; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf22.hostedemail.com: domain of djwong@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=djwong@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1762973206; a=rsa-sha256; cv=none; b=j/TCGHjZt6XwOyvQNqTyNUzK9zF2eNWGDeQLNlzE4GnGeqezV7PPkprN88hAiFmT5QBfrn UabbagosOkgLwZf5FsvFKBFVvFMAu8tdll5S2maId/ijoTHVlZDMXX/7w+yPsSs/Zdqail BlPYfpW/yVJOnWAhfy+EkhxPO/SMtPQ= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=R2Mov+CO; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf22.hostedemail.com: domain of djwong@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=djwong@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762973206; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6Re2sICsdgyxCqiBkftjgTq0gYDYTvzcaYSiiKGrCtM=; b=7LCIo0JixEwWhH27CcNYI9VoRycFIZKfzktMsjlT+sqMNTwHNlC/TGY/USkiju2o0lQz17 h46DspUx/Cp1PF3TvjsTS+mvVVJBeUjZMSdEx6ksMbQU/A8TN7Dd2Jf8iKS0MtFX7ojsH5 NOyU/09uqiMqA/qPmQUFr06ubFKhK7w= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 11FFF601B9; Wed, 12 Nov 2025 18:46:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEC00C4CEF1; Wed, 12 Nov 2025 18:46:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762973205; bh=krRamLEqJ+J5dF6rh+U31wEuWVMhuLkU4t9gOAmZ0OE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=R2Mov+COKEabe79YruowLosyU1B9c+7Ssg7UKsnJsukXN3dk8ZHtyiu68onzQhRue IQNECIN2Sq/XHxkgNwkdWbGe0xltqAbgGFMPrXrQ5QXbYg4NLtJK+qfK2uvOxGTeY5 58ngu3VeUAQlSymQMImL1H6oHX+PqNdvPEUbJbXqUG8pQEcAWyLTeUG9FiDURNJQEi JOIYQefErLetJe3gVWKOrgbng6/SibP04GhiLfI/rdhbPWzEwkTve33jjmWUi7yOfJ LH2J4ejQ4uRCLxnxPprxwAN/jmUA/J3HkvtkXaJGuvNT/sMa/f6Q0A5UYZhwH0m/zf PALetnJ93sBjA== Date: Wed, 12 Nov 2025 10:46:45 -0800 From: "Darrick J. Wong" To: Harry Yoo Cc: Andrew Morton , Vlastimil Babka , "Liam R . Howlett" , Tytus Rogalewski , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org Subject: Re: [PATCH V1] mm/slub: fix memory leak in free_to_pcs_bulk() Message-ID: <20251112184645.GP196391@frogsfrogsfrogs> References: <20251111125331.12246-1-harry.yoo@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251111125331.12246-1-harry.yoo@oracle.com> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: D4714C0016 X-Stat-Signature: azbpd68uemw3bnkp7jonc6n5g1k9uatx X-Rspam-User: X-HE-Tag: 1762973206-3995 X-HE-Meta: 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 FXWYiQ2f KuDXF 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: List-Subscribe: List-Unsubscribe: On Tue, Nov 11, 2025 at 09:53:31PM +0900, Harry Yoo wrote: > The commit 989b09b73978 ("slab: skip percpu sheaves for remote object > freeing") introduced the remote_objects array in free_to_pcs_bulk() to > skip sheaves when objects from a remote node are freed. > > However, the array is flushed only when: > 1) the array becomes full (++remote_nr >= PCS_BATCH_MAX), or > 2) slab_free_hook() returns false and size becomes zero. > > When neither of the conditions is met, objects in the array are leaked. > This resulted in a memory leak [1], where 82 GiB of memory was allocated > for the maple_node cache. > > Flush the array after successfully freeing objects to sheaves > in the do_free: path. > > In the meantime, move the snippet if (!size) goto flush_remote; outside > the while loop for readability. Let's say all objects in the array are > from a remote node: then we acquire s->cpu_sheaves->lock and try to free > an object even when size is zero. This doesn't appear to be harmful, > but isn't really readable. I'll put this on my test fleet this evening. Thank you for the quick fix! :) --D > Reported-by: Tytus Rogalewski > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220765 [1] > Closes: https://lore.kernel.org/linux-mm/20251107094809.12e9d705b7bf4815783eb184@linux-foundation.org > Closes: https://lore.kernel.org/all/aRGDTwbt2EIz2CYn@hyeyoo > Fixes: 989b09b73978 ("slab: skip percpu sheaves for remote object freeing") > Signed-off-by: Harry Yoo > --- > mm/slub.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index f1a5373eee7b..a787687a0d59 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -6332,8 +6332,6 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) > > if (unlikely(!slab_free_hook(s, p[i], init, false))) { > p[i] = p[--size]; > - if (!size) > - goto flush_remote; > continue; > } > > @@ -6348,6 +6346,9 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) > i++; > } > > + if (!size) > + goto flush_remote; > + > next_batch: > if (!local_trylock(&s->cpu_sheaves->lock)) > goto fallback; > @@ -6402,6 +6403,9 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) > goto next_batch; > } > > + if (remote_nr) > + goto flush_remote; > + > return; > > no_empty: > -- > 2.43.0 >