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 3997F437107 for ; Tue, 29 Sep 2026 06:44:07 +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=1790664249; cv=none; b=MHZqxx8qVq6b8hqzifng+PD2EeHBcMWSqJjUKBDvelnawAhqDNJZhomN/OfjXQwxjfc3k4OUpn8mqDvD32ZOue1MWl2TNr/4cbqRwYduC64VxBzco0KoB7cCosFVrWgTUJs09a8t3OIUTPYLHAUBJgXvX5pQTC7oMGKEecLzh3M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790664249; c=relaxed/simple; bh=ZHAdUWpXk+vpzWIx641Qnqc0llVETm/ICt9yx35Igbg=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=BpSpVUWOAuh1FkA395fMbgn35zSSfycbunr5YNg6VsxWwQ06HpZ7Nsuidv0t+t/nZxykQaYWV+E80QetbdG7WN4VptIkB1t6Z1wsIp4YOiMaVScrMgSAWsvtSDmCnCdwTyHdIAeWUEgscrd29ob90FtI1dKtFlma3+6ty6WoYxI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dxA43MUq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dxA43MUq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A9B61F000FF; Tue, 29 Sep 2026 06:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790664247; bh=6eqUW6B0umHOLhTKKIAHCJ2vDTRaE7xcK1B+tjs7F54=; h=Subject:To:Cc:From:Date; b=dxA43MUqhD8jguZDLCRtAhtjWVqvYV37iYKl+Amfu0NFUPiv08IHF5x4TNCSEHr4K xUCu0LSA3wsEMJClBqQs0t3aCXpk8HqFVezTL4u9cXSnZVUVkFJsSYiXbTJBf3uOTg WiLtq1fs7/0bLnTp5l77N99VptU8Ajbdxol8ytzs= Subject: FAILED: patch "[PATCH] fs/ntfs3: use d_instantiate_new() in ntfs_create_inode() and" failed to apply to 6.6-stable tree To: brauner@kernel.org,jack@suse.cz Cc: From: Date: Tue, 29 Sep 2026 08:44:04 +0200 Message-ID: <2026092904-porthole-attire-bdfd@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 1abd643f3783ea8f8e273c18697ff0413aa92dc7 # git commit -s git send-email --to '' --in-reply-to '2026092904-porthole-attire-bdfd@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1abd643f3783ea8f8e273c18697ff0413aa92dc7 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 9 Sep 2026 11:03:18 +0200 Subject: [PATCH] fs/ntfs3: use d_instantiate_new() in ntfs_create_inode() and murder syzbot's "WARNING in do_new_mount" saga ntfs_create_inode() creates a new inode via ntfs_new_inode(). It hashes it with insert_inode_locked() and so it's marked as I_NEW until unlock_new_inode(). ntfs 3 calls d_instantiate() in between though... Since the dentry was already hashed by the lookup before the create any path walk finds it without touching the parent's i_rwsem and so can lock the inode. If the inode is a directory unlock_new_inode() calls lockdep_annotate_inode_mutex_key() and marks i_rwsem with the i_mutex_dir_key class. That resets the count and the owner of a lock somebody else may already hold by now... syzbot has been spamming us with the same godforsaken bug "WARNING in do_new_mount" since 2023. I can't take it anymore so I went looking. Afaict, syzbot's executor chdirs into a freshly mounted ntfs3 image, creates a directory and then mounts some pseudofs on it. Everytime the mkdir() takes longer than syzbot waits mount() runs concurrently: mkdir("./sys") mount(NULL, "./sys", "sysfs") ntfs_create_inode() d_instantiate() user_path_at() finds the dentry do_lock_mount() inode_lock(inode) namespace_lock() unlock_new_inode() lockdep_annotate_inode_mutex_key() init_rwsem(&inode->i_rwsem) unlock_mount() inode_unlock(inode) The mount side then releases a lock that according to the rwsem nobody holds: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && ...): count = 0x0, magic = 0xffff888043a854e8, owner = 0x0, curr 0xffff888000244880, list empty WARNING: CPU: 0 PID: 5346 at kernel/locking/rwsem.c:1368 __up_write Call Trace: inode_unlock include/linux/fs.h:877 [inline] unlock_mount fs/namespace.c:2892 [inline] do_new_mount_fc fs/namespace.c:3828 [inline] do_new_mount+0x777/0xa40 fs/namespace.c:3887 On PREEMPT_RT the same thing shows up as DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current) WARNING: kernel/locking/rtmutex_common.h:193 at rt_mutex_slowunlock The up_write() underflows the reset count. A following inode_lock() on that directory then never returns. A path walk into the new directory racing with the mkdir() corrupts the lock the same way via inode_lock_shared() in lookup_slow(). Switch to d_instantiate_new() and drop the trailing unlock_new_inode(). All error paths bail out before that point with I_NEW still set and keep using discard_new_inode(). May we never see this fscking bug report again. Link: https://patch.msgid.link/20260909-work-ntfs3-d_instantiate_new-v1-1-2db697162ce8@kernel.org Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block") Reviewed-by: Jan Kara Cc: stable@vger.kernel.org # v5.15+ Reported-by: syzbot+2a13ad6914e6fcec716c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/6a9beced.a5e650b3.26d8a.000b.GAE@google.com Signed-off-by: Christian Brauner (Amutable) diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c index 56b4f6469a28..4ac26c80bd34 100644 --- a/fs/ntfs3/inode.c +++ b/fs/ntfs3/inode.c @@ -1866,10 +1866,10 @@ int ntfs_create_inode(struct mnt_idmap *idmap, struct inode *dir, goto out6; /* - * Call 'd_instantiate' after inode->i_op is set + * Call 'd_instantiate_new' after inode->i_op is set * but before finish_open. */ - d_instantiate(dentry, inode); + d_instantiate_new(dentry, inode); /* Set original time. inode times (i_ctime) may be changed in ntfs_init_acl. */ inode_set_atime_to_ts(inode, ni->i_crtime); @@ -1917,9 +1917,6 @@ int ntfs_create_inode(struct mnt_idmap *idmap, struct inode *dir, if (!fnd) ni_unlock(dir_ni); - if (!err) - unlock_new_inode(inode); - return err; }