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 7FACC13FD86; Tue, 26 Aug 2025 12:51:57 +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=1756212717; cv=none; b=IbazcHJulW2K9qItAPLbDzgSlSxQlm5CicOFnvH4FQhDntln5HJmAZ5kH5+qOGCdTTPVYoegmCtAQTSubeaKBNIVFa1YOjhu1xqNsxOO0RJvdeoGZZ37WXI8vjapDiLrbABwzAUN+jkskrjCGxnozLvbRKBgCpabw6yRYzU+A2s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756212717; c=relaxed/simple; bh=LpZM6NHQwTkst2t78qOjdJVi/op7pGjRzdqQH9KQ4U8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bhWEggaGy8xsWyagjAVX5CLXO7yA43M89p3ml3u+mbeQNrs/ebr2w6L6qY5uSdSORFUBueyT7jRXQMPlqk/zimGs30qiggeqzbLKalEHUXZpaDdwn9QC16B6dXoLsSlMEZzeWSrVykVlsaQr96EaZzneGggOhJ4q6CVFAN57+Uk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bcfp6+rl; 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="bcfp6+rl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03CA8C4CEF4; Tue, 26 Aug 2025 12:51:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756212717; bh=LpZM6NHQwTkst2t78qOjdJVi/op7pGjRzdqQH9KQ4U8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bcfp6+rlHdYD7uf6BSxTVO+Z+K6R4wc0+rRcbaf5bfF4t/3707oQjMFORgr6t6OLV 7OWopFhF3Uce14mJo2hml77R6j1cpu3HsXl7Z8bTW+A0JauwwNsBsEd6bdRDI8ZokG 7g40IpUBgtwUIdEIXNMEy1TSmBL06fixm6IlAIRc= 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 6.6 075/587] better lockdep annotations for simple_recursive_removal() Date: Tue, 26 Aug 2025 13:03:44 +0200 Message-ID: <20250826110954.841628673@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110952.942403671@linuxfoundation.org> References: <20250826110952.942403671@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 6.6-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 f5566964aa7d..b913ab238cc1 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -610,7 +610,7 @@ 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) { @@ -622,7 +622,7 @@ 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