[PATCH v2 1/4] locking/mutex: implement mutex_trylock_nested

[Peter Zijlstra]

On Tue, Apr 08, 2025 at 09:41:33PM -0400, Maxim Levitsky wrote:
> Allow to specify the lockdep subclass in mutex_trylock
> instead of hardcoding it to 0.

We disable a whole bunch of checks for trylock, simply because they do
not wait, therefore they cannot deadlock.

But I can't remember if they disable all the cases required to make
subclasses completely redundant -- memory suggests they do, but I've not
verified.

Please expand this Changelog to include definite proof that subclasses
make sense with trylock.