Re: [syzbot] [efi?] [fs?] possible deadlock in efivarfs_actor

[Al Viro]

On Mon, Mar 10, 2025 at 07:21:53PM +0100, Ard Biesheuvel wrote:

> The repro log also has
> 
> program crashed: BUG: unable to handle kernel paging request in
> efivarfs_pm_notify
> 
> preceding the other log output regarding the locks, so the deadlock
> might be a symptom of another problem.

This:
        struct path path = { .mnt = NULL, .dentry = sfi->sb->s_root, };

_What_ .mnt = NULL?  That's already a bug.  There is no such thing
as mountless open file; how would the kernel know not to shut the
damn thing down right under you?