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 7D306261B97; Mon, 18 Aug 2025 13:49:02 +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=1755524942; cv=none; b=YOuFdd3Fqbd1xASoNDRbJDErmSpqhQiaY/a2XZoMZcAIT8PavpFQZZx8W6IpnWcPIlJ7V1lkYYkAOZ8FqLmMAcoie5CTCzud/OwAv8jWxfEQdrzluLWBjrGKYWCmoomXPlamNRw5+wLX2G8UG1lCBl/P4jxOaZA11ajvt4pZH4Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524942; c=relaxed/simple; bh=KcuREEYYg9cGjxj3lw8GstM6psQyxJXs8tXUO15Dqz0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GQhwxbZQ5BPJMNk2/FyxTdO4ufinIp0sUQ5vbEqdzX9MdSLKpp4lOIOl6O+e+k2iR1fZxKxvL+lA1V6rVON953b4T+Y0+0ZlMK/0hnRV9gEAD/YKw+lqEEmmzP3Vefo5VVPCfwW8j2BcRGJbuvF7oDG1cpf2NyE6mhkXhPDqbn4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=K/8hCBPB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="K/8hCBPB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A6E8C4CEF1; Mon, 18 Aug 2025 13:49:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755524942; bh=KcuREEYYg9cGjxj3lw8GstM6psQyxJXs8tXUO15Dqz0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K/8hCBPBe4n8HteW3gWdlY6Vkfzhx5y2vwRcSERtvUHAi50FAR7qeJ8jjF79kc49V zKye2I0BsgFFyODP0qsNij0x4OhFfwhKsnUzMlZ8Fa2BdQoTlEKmc1DorRlvbXpCAh E1Dt6m+FZNSHYOzlhUAIv/NARDAzeoKUlp8aBphk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+169de184e9defe7fe709@syzkaller.appspotmail.com, Al Viro , Sasha Levin Subject: [PATCH 6.16 111/570] better lockdep annotations for simple_recursive_removal() Date: Mon, 18 Aug 2025 14:41:38 +0200 Message-ID: <20250818124510.081282823@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124505.781598737@linuxfoundation.org> References: <20250818124505.781598737@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro [ Upstream commit 2a8061ee5e41034eb14170ec4517b5583dbeff9f ] We want a class that nests outside of I_MUTEX_NORMAL (for the sake of callbacks that might want to lock the victim) and inside I_MUTEX_PARENT (so that a variant of that could be used with parent of the victim held locked by the caller). In reality, simple_recursive_removal() * never holds two locks at once * holds the lock on parent of dentry passed to callback * is used only on the trees with fixed topology, so the depths are not changing. So the locking order is actually fine. AFAICS, the best solution is to assign I_MUTEX_CHILD to the locks grabbed by that thing. Reported-by: syzbot+169de184e9defe7fe709@syzkaller.appspotmail.com Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/libfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 6f487fc6be34..972b95cc7433 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -613,7 +613,7 @@ void simple_recursive_removal(struct dentry *dentry, struct dentry *victim = NULL, *child; struct inode *inode = this->d_inode; - inode_lock(inode); + inode_lock_nested(inode, I_MUTEX_CHILD); if (d_is_dir(this)) inode->i_flags |= S_DEAD; while ((child = find_next_child(this, victim)) == NULL) { @@ -625,7 +625,7 @@ void simple_recursive_removal(struct dentry *dentry, victim = this; this = this->d_parent; inode = this->d_inode; - inode_lock(inode); + inode_lock_nested(inode, I_MUTEX_CHILD); if (simple_positive(victim)) { d_invalidate(victim); // avoid lost mounts if (d_is_dir(victim)) -- 2.39.5