Re: [PATCH v3] block: assign caller-specific lockdep class to disk->open_mutex

[Miguel Ojeda]

On Fri, Jun 5, 2026 at 2:04 PM Mark Brown <broonie@xxxxxxxxxx> wrote:
>
> Oh, bah - something turned off RUST in allmodconfig again so we lost
> coverage in -next, sorry about that.  I'll need to work something out to
> make sure I notice that happening and can do something about it.  It's
> kind of worrying that this keeps happening TBH, otherwise rust conflicts
> are likely to result in broken builds.  The dependencies feel really
> fraigle here.
>
> Had the rust builds been enabled for allmodconfig as I had expected the
> tree would have been kept out of -next as a result of this.

No worries at all, and thanks a lot for testing it, as usual. I am
happy to be there as a backup to catch extra things.

I Cc'd you since I was wondering if your new `LLVM=1` build should
have caught it (I thought the GCC one wouldn't, since my understanding
is that we lost that last week due to the KASAN+RUST patch).

And, yeah, it is fragile... It is quite a complicated set of Kconfig
relationships, so years ago I also ended up in the same situation and
early on decided to add an explicit grep for `CONFIG_RUST=y` and
certain other bits that I wanted to ensure are in place after the
config phase.

Especially the toolchain side, i.e. the fact that `CONFIG_RUST` gets
automatically disabled if the Rust toolchain is not found, is
particularly subtle. We are considering finally changing that to fail
the build:

  https://lore.kernel.org/rust-for-linux/20260521-evolve-to-crab-v2-1-c18e0e98fc54@xxxxxxxxxxxxxx/

For you and those building with Rust enabled it would be great to
notice when it gets disabled by mistake, but I am not sure if most
maintainers (i.e. those without a Rust toolchain but using
`all*config` routinely) will appreciate it (or rather, tolerate it...
:).

It may be too soon -- I considered announcing it in linux-next and
adding the patch early next cycle to see what happens, but I will
probably take the safer route and ask in LPC first, unless you think
it is a good idea. Any feedback/suggestions appreciated!

Cheers,
Miguel