From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.247 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793266317; b=1XoXf/YAqCwBvjmjZCm6Vtb8gZEbbMOd/5Dxs52TEnkv/kpVoC0f8KEo+ga19ydFv8tB wSueN+36RHIW08xgbKXsBfHD3vDMEgPudu1O+X7j/GfXMzDGl71orivV+j0aAs0OcLCKc SAm5s5j8lTj/X8N9wNh4fC/jrYPZleXMJrAXJgLCDzIw7mymgn8g4jlydDFzxnCBmwQxm ocbsfODsAksDcgpMVO/PVF1Oa2Rv4w4Bq7HcfVEBGhMleuBc7GFTbq9aAlsE4oAiFcyAv Cr08TutyuYV+BYwEXstVD6NXsKclzQ+eFZnpoqP1T8T5RGMFlt4oiOMWlyZM0BG+vxQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793266317; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=okptCD3UTwIXdaRJonCEkQqFEfGDTbXbfiDDvu4kuWg=; b=1oNzo8GxmjMjNwCQIEXfkh5/iXnQNxAIvvsDONg1wQHhohcReFlOId0wcXyfFP1QjCqs yKelPP9QFWmcj0nbMLnTbQoIpoDMKLrZVJn6nyJLEzWsuqltwDvdP317e0dZXuVU9eliT BxtWhfR2ktMt5TNxXqAN65dTUrNGkeddmm5L6tCGrOdL78szOi4sEcqSb8TbRugiiP8RP I5+q0GNZ2ldrV4wC/9Oy2fz3VEef/ZCEHdh9wLXWGgAQaAlXPWc8mueazxHXKkLP5mirg qB/aZFFlw28we1vPxIDDI3R9nCgmvK3QGQVdwVq+dquB2mdOLFIPvOLxBw7qu6XJ8zA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b="pN1/33dJ"; arc=none smtp.remote-ip=91.218.175.247 Received: from mta0.migadu.com (out-247.mta0.migadu.com [91.218.175.247]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00337606A327 for ; Thu, 29 Oct 2026 09:31:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 00337606A327 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=pN1/33dJ X-Envelope-To: linux-fsdevel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=RV02fKHXp15N1sora8/JC7gfty5QHQabj6vGISh62x8=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793266315; v=1; x=1793871115; b=pN1/33dJVwRqFONKhLklqHMutpUamuhZu2AZye1lIQaTJs8hbPF6bTcf+cXJU55EZ7qfRbEN VqLnxOcNfSnhjKZfdIqtIYcR6Mu/HJrSU/0xS3cnfMzfLhPjO4jcmpN8tgFxuhUzDAuWgKb+pWN +Ay+0iVCC/HouO+wrJe02qgM= X-Envelope-To: linux-fsdevel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id fbff33db7aa8f017; Thu, 29 Oct 2026 09:31:54 +0000 X-Mizu-Trace-ID: fbff33db7aa8f017 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Thu, 29 Oct 2026 17:31:50 +0800 X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fs: fix ramfs_fs_info leak when rootfs is unmounted To: Karl Mehltretter Cc: Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, John Paul Adrian Glaubitz References: <20261009055546.85279-1-kmehltretter@gmail.com> Content-Language: en-US From: Zenghui Yu In-Reply-To: <20261009055546.85279-1-kmehltretter@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/9/26 1:55 PM, Karl Mehltretter wrote: > When rootfs is a ramfs, for example with root= on the command line, its > superblock carries a struct ramfs_fs_info from ramfs_init_fs_context(). > ramfs_kill_sb() frees it, but rootfs_fs_type uses kill_anon_super(). > > Before commit 576ee5dfd459 ("fs: add immutable rootfs") rootfs could not > be unmounted. Since then prepare_namespace() pivots into the real root > and unmounts rootfs. When the superblock is destroyed, the structure is > leaked. kmemleak on an SH7785LCR board: > > unreferenced object 0x8100a720 (size 32): > comm "swapper/0", pid 0, jiffies 4294892299 > backtrace (crc c8bfd23b): > ... > ramfs_init_fs_context+0x16/0x48 > rootfs_init_fs_context+0x16/0x2c > alloc_fs_context+0x98/0x114 > fs_context_for_mount+0x16/0x24 > ... > > Call ramfs_kill_sb() when rootfs is a ramfs. tmpfs frees its own data > in put_super and keeps kill_anon_super(). > > Fixes: 576ee5dfd459 ("fs: add immutable rootfs") > Reported-by: John Paul Adrian Glaubitz > Assisted-by: LLM > Signed-off-by: Karl Mehltretter Tested-by: Zenghui Yu (Huawei) Thanks, Zenghui