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

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Date: Tue, 13 Feb 2024 14:21:31 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: Lokesh Gidra <lokeshgidra@...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

* Suren Baghdasaryan <surenb@...gle.com> [240213 13:57]:
..

> >
> > Yes, I don't think we should be locking the mm in lock_vma(), as it
> > makes things hard to follow.
> >
> > 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.
> 
> 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.

The issue I have is the vma in the name - we're not doing anything to
the vma when we mmap_lock.

> Anyway, I don't see this as a blocker, just nice to have.

Yes, that's how I see it as well.