From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5E0C38CFEE; Mon, 2 Mar 2026 08:39:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772440795; cv=none; b=U9uxERHCoLG+lpDTXkKhyIy/SI7N4ax1Ui19NjePiRxfD+9xb+Y0vB/QtQncwBQY6L8OxItajjnVHSDP/RrO1HraHfbsGQ3OaYLYzIsGGoLW1t4ywv2P/kfHEop611EjdIq0grLCdzRiRtUBSlb/q0w+sdbzqv9mzO30fPm2uio= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772440795; c=relaxed/simple; bh=IK6yz5KkVHkPj52iCRrJqonMHigRB4kCqBYdPevwYOQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bSLqorcEJBY4z7rnrmfWR1y9KmCvKmAe77f4RyDIwz4zJWIUDm9obKQuLCeZx78t+n1nLsCee62Mwe4DzQFqW/zl+XLl3mf+IHAEjpQu47pQu6CT7fHcaUuPaTxzJhZdpIpYblFsoFigQ8PuL1juS1WGFlFd1vxG5cY0q8Zpe0o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rR6hqX6k; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rR6hqX6k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCE99C19423; Mon, 2 Mar 2026 08:39:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772440794; bh=IK6yz5KkVHkPj52iCRrJqonMHigRB4kCqBYdPevwYOQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=rR6hqX6k7Jy2Fsq/qNTQTzsicRzKK5XKCMn38lSUnx79QM1kS0YTg+FZdrPkMHhAM xRPvlxsCD6cQ7hnoBGUd8fKi6lPHVSYnu198wRmEaOO7qtN1DTs/uXwmUi3YCIDUCs HvW95YTyPNv5VrWq0kLVxiuE+I2fMO7oWMOuu/Z8PHG5PLDCFmzza5g4Mq6FdMwfwk 5pLAmKlWAb3GNqbbp7VGzgnzcjHDwEoI65qHQk4nXNMC4EzvWhOKLaQEKojCQX++Fo Nmwq8cQ95fgGX+Bpr/QA7y3zMbx0y7W8w9wHiIFn0XBXFaFsSr6yHrEcGQ7Vrx/Iul d2CRZOgiHQyCQ== Message-ID: <20df8dd1-a32c-489d-8345-085d424a2f12@kernel.org> Date: Mon, 2 Mar 2026 09:39:48 +0100 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] [f2fs?] [exfat?] memory leak in __kfree_rcu_sheaf Content-Language: en-US To: Qing Wang , syzbot+cae7809e9dc1459e4e63@syzkaller.appspotmail.com Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, chao@kernel.org, jaegeuk@kernel.org, jannh@google.com, linkinjeon@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, pfalcato@suse.de, sj1557.seo@samsung.com, syzkaller-bugs@googlegroups.com, vbabka@suse.cz, Harry Yoo , Hao Li References: <698a26d3.050a0220.3b3015.007e.GAE@google.com> <20260302034102.3145719-1-wangqing7171@gmail.com> From: "Vlastimil Babka (SUSE)" In-Reply-To: <20260302034102.3145719-1-wangqing7171@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/2/26 04:41, Qing Wang wrote: > #syz test > > diff --git a/mm/slub.c b/mm/slub.c > index cdc1e652ec52..387979b89120 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -6307,15 +6307,21 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj) > goto fail; > > if (!local_trylock(&s->cpu_sheaves->lock)) { > - barn_put_empty_sheaf(barn, empty); > + if (barn && data_race(barn->nr_empty) < MAX_EMPTY_SHEAVES) > + barn_put_empty_sheaf(barn, empty); > + else > + free_empty_sheaf(s, empty); > goto fail; > } > > pcs = this_cpu_ptr(s->cpu_sheaves); > > - if (unlikely(pcs->rcu_free)) > - barn_put_empty_sheaf(barn, empty); > - else > + if (unlikely(pcs->rcu_free)) { > + if (barn && data_race(barn->nr_empty) < MAX_EMPTY_SHEAVES) > + barn_put_empty_sheaf(barn, empty); > + else > + free_empty_sheaf(s, empty); > + } else > pcs->rcu_free = empty; > } I don't think this would fix any leak, and syzbot agrees. It would limit the empty sheaves in barn more strictly, but they are not leaked. Hm I don't see any leak in __kfree_rcu_sheaf() or rcu_free_sheaf(). Wonder if kmemleak lacks visibility into barns or pcs's as roots for searching what objects are considered referenced, or something?