linux-kernel - Re: [syzbot] [bcachefs?] possible deadlock in bch2

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Message-ID: <20250804032312.GX222315@ZenIV>
Date: Mon, 4 Aug 2025 04:23:12 +0100
From: Al Viro <viro@...iv.linux.org.uk>
To: Alan Huang <mmpgouride@...il.com>
Cc: syzbot <syzbot+7836a68852a10ec3d790@...kaller.appspotmail.com>,
	kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org,
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
	miklos@...redi.hu, amir73il@...il.com,
	linux-unionfs@...r.kernel.org
Subject: Re: [syzbot] [bcachefs?] possible deadlock in bch2_symlink

On Mon, Aug 04, 2025 at 11:02:54AM +0800, Alan Huang wrote:
> +cc overlayfs

Sigh...

1) ovl_copy_up_workdir() should lock wdir with I_MUTEX_PARENT, same
as filename_create().

2) what the hell is bch2_symlink() need to lock the new inode for?
page_symlink() doesn't need that; are there any bcachefs-specific reasons
to bother with that?