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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 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 X-Stat-Signature: uewpfnnogeefbugapwj441mrofuzsagi X-Rspamd-Queue-Id: 524E516000B X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1779248526-383413 X-HE-Meta: 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 An9XQK09 5ZEl0ENCRePrMaFGAwl+yRGqSaSzBE9vMNINqLCtwryYnZHC6IZOgoweYFLMWDUGEJbl98yDeJNrafQHWd5DU9g+qKPK7U3b63EMeiR8YukKc5o5GTbiZp7ZvSQKE+6519oPI8u2sGkp0YxRflAm6fXwJf1q2RwH3PmIcu10sLfLtgushKU1NuNQ1QMnvaTzzm2Y6LBONrncN0tbZlBu5VAEi4LtDwXUJAqIsjdGG1cVNV1TYg86RW5K2yVoN7ZFEp08v86lrh0vNdbf2ErOXuSo4edgfiK9GRChlQVSO2oZTx1MYgh0qSjN9tfENdoUtsAG4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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