Subject: linux-next: build failure after merge of the tip tree

From: Stephen Rothwell <[email-masked]>
Date: Wed, 22 Oct 2025 11:46:44 +1100

Hi all,

After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
failed like this:

error[E0594]: cannot assign to data in dereference of `lock::Guard<'_, T, MutexBackend>`
  --> rust/kernel/debugfs/traits.rs:64:9
   |
64 |         *self.lock() = val;
   |         ^^^^^^^^^^^^ cannot assign
   |
   = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `lock::Guard<'_, T, MutexBackend>`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0594`.

Caused by commit

  da123f0ee40f ("rust: lock: guard: Add T: Unpin bound to DerefMut")

I have used the tip tree from next-20251021 for today.

-- 
Cheers,
Stephen Rothwell