linux-kernel - Re: [PATCH v4 3/3] userfaultfd: use per-vma locks in userfaultfd operations

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Date: Mon, 12 Feb 2024 17:53:12 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Lokesh Gidra <lokeshgidra@...gle.com>
Cc: akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        selinux@...r.kernel.org, surenb@...gle.com, 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 v4 3/3] userfaultfd: use per-vma locks in userfaultfd
 operations

* Lokesh Gidra <lokeshgidra@...gle.com> [240212 17:31]:
> I have also introduced a handler for finding dst_vma and preparing its
> anon_vma, which is used in lock_vma() and find_vmas_mm_locked().
> 
> Sounds good?
> 
> > I've also thought of how you can name the abstraction in the functions:
> > use a 'prepare() and complete()' to find/lock and unlock what you need.
> > Might be worth exploring?  If we fail to 'prepare()' then we don't need
> > to 'complete()', which means there won't be mismatched locking hanging
> > around.  Maybe it's too late to change to this sort of thing, but I
> > thought I'd mention it.
> >
> Nice suggestion! But after (fortunately) finding the function names
> that are self-explanatory, dropping them seems like going in the wrong
> direction. Please let me know if you think this is a missing piece. I
> am open to incorporating this.

This plan sounds good, thanks!

Regards,
Liam