linux-kernel - Re: [PATCH v5 3/3] userfaultfd: use per-vma locks in userfaultfd operations

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Date: Tue, 13 Feb 2024 14:27:44 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Lokesh Gidra <lokeshgidra@...gle.com>
Cc: Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, selinux@...r.kernel.org,
        kernel-team@...roid.com, aarcange@...hat.com, peterx@...hat.com,
        david@...hat.com, axelrasmussen@...gle.com, bgeffon@...gle.com,
        willy@...radead.org, jannh@...gle.com, kaleshsingh@...gle.com,
        ngeoffray@...gle.com, timmurray@...gle.com, rppt@...nel.org
Subject: Re: [PATCH v5 3/3] userfaultfd: use per-vma locks in userfaultfd
 operations

* Lokesh Gidra <lokeshgidra@...gle.com> [240213 14:18]:
..

> > > We could use something like uffd_prepare(), uffd_complete() but I
> > > thought of those names rather late in the cycle, but I've already caused
> > > many iterations of this patch set and that clean up didn't seem as vital
> > > as simplicity and clarity of the locking code.
> 
> I anyway have to send another version to fix the error handling that
> you reported earlier. I can take care of this in that version.
> 
> mfill_atomic...() functions (annoyingly) have to sometimes unlock and
> relock. Using prepare/complete in that context seems incompatible.
> 
> >
> > Maybe lock_vma_for_uffd()/unlock_vma_for_uffd()? Whatever name is
> > better I'm fine with it but all these #ifdef's sprinkled around don't
> > contribute to the readability.
> 
> I'll wait for an agreement on this because I too don't like using so
> many ifdef's either.
> 
> Since these functions are supposed to have prototype depending on
> mfill/move, how about the following names:
> 
> uffd_lock_mfill_vma()/uffd_unlock_mfill_vma()
> uffd_lock_move_vmas()/uffd_unlock_move_vmas()
> 
> Of course, I'm open to other suggestions as well.
> 

I'm happy with those if you remove the vma/vmas from the name.