From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 ECC3031282F for ; Wed, 20 May 2026 03:42:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779248531; cv=none; b=kJLCLEbVtYDLJRYKzVKmNG/vw7nH8ch5/+kY/d6HiGExN5SA31wMqxNCEc5ScJ52K9j+ytDCrEdcMrKEb+H6ez1yJrSG2FD73beOxVdzA+ahAaO9Z+WIPXhoZAJo01v3hqbSPv6D5RchfyLEe5hdymE00gbDdLfx1edrtAOCS78= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779248531; c=relaxed/simple; bh=4xdePMbQmpvx72uRNnK4cwF2mXE3me0GmTh0pOK51JM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=K62XCDkUVLwGR31buejSe8nqLnwsw9lqcJTHF7DVLiJfier0iqFL+kTB4C67Ek9kB5ynT/DwHPv1Cume+J2Y1gZGgbwaLeB2xwmw3TPbeWrJfXf3Xl6y8sohXVf00WH4aJkVcIpEShNXElBUKBlMuGbHZoB1Feev2SU1q2+nx80= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VA2F7P9O; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VA2F7P9O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E38A1F000E9; Wed, 20 May 2026 03:42:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779248525; bh=UfFs7ljUUn5ctVcdiPiZ8Wx+0rgfOs9EiT85UFleKDs=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=VA2F7P9OYS10pVfJgs1MmK9a5HqkOjZF71WQL4NBlojEfveLSJkDTovu5Et01/NsV BWNsJGLhFNg/ULzg6ZCaR6y+slGOVMcBt0nC0Tr9YEuqSHOaVEb63GA761nwwrY4aI hUrgCD8yGzQHiCalrMs7yppZDCY0ewqG+ll+97s0qnU1pOrGrO+K9UXJUtEAVzz1W0 6p7IqjJUOhNiHosp+AXEyze914unbxRpxNJ3+UrqGUNwZuFSzg+wSm0Dn+lxT13mwb 3+ixGO6DAhqV2t1uR2QHXKF0DOWUNRH3KOaadR9K+b4WVvjaix76E7Xou3en50mHOF vMeo6crJXrvlQ== Message-ID: <8a80496b-1568-4a0b-a878-836c27d19ad5@kernel.org> Date: Wed, 20 May 2026 12:42:02 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/slab: fix probable issue of dentries registration under /sys/kernel/slab To: Vladimir Zapolskiy , Vlastimil Babka , Andrew Morton , Christoph Lameter , Hao Li Cc: David Rientjes , Roman Gushchin , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260520011019.1707010-1-vladimir.zapolskiy@linaro.org> Content-Language: en-US From: Harry Yoo In-Reply-To: <20260520011019.1707010-1-vladimir.zapolskiy@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/20/26 10:10 AM, Vladimir Zapolskiy wrote: > L2TP/IP and L2TP/IPv6 protocol names contain a slash symbol, however these > names are blindly used as symlinks to slab cache objects registered under > /sys/kernel/slab. This kind of symlink creation is successful, but its > dentry is obviously broken, as well it breaks the access to the list of > /sys/kernel/slab dentries. Oops. I just loaded l2tp_ip module and it indeed broke it. $ ls ls: reading directory '.': Input/output error :0000136/ kmalloc-rnd-01-16/ kmalloc-rnd-15-32/ :0000192/ kmalloc-rnd-02-512/ memdup_user-32/ :0000560/ kmalloc-rnd-06-192/ memdup_user-4k/ :0000768/ kmalloc-rnd-06-512/ pde_opener@ :a-0000168/ kmalloc-rnd-07-4k/ pidfs_xattr_cache@ :A-0000184/ kmalloc-rnd-11-8/ RAWv6/ audit_buffer@ kmalloc-rnd-11-96/ rpc_inode_cache/ configfs_dir_cache@ kmalloc-rnd-12-4k/ task_delay_info@ ecryptfs_global_auth_tok_cache@ kmalloc-rnd-13-128/ TCPv6/ fscache_cookie_jar@ kmalloc-rnd-14-96/ io_kiocb/ kmalloc-rnd-15-2k/ > Likely L2TP protocol renames cannot be done, since the defined protocol > names are exposed over /proc/net/protocols for years, but the symlink > names can be renamed, because they are yet to be properly created, and > this should be eventually done by this change. > > The problem manifests itself, if CONFIG_L2TP_IP build symbol is selected. > > Fixes: 81819f0fc8285 ("SLUB core") > Signed-off-by: Vladimir Zapolskiy > --- There is also a debugfs feature that would cause a similar issue. Can we replace '/' in the cache name, without renaming the protocol name? -- Cheers, Harry / Hyeonggon