linux-kernel - Re: [PATCH v4 5/5] selftests/mm: add UFFDIO

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Date:   Mon, 30 Oct 2023 16:35:27 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
        brauner@...nel.org, shuah@...nel.org, aarcange@...hat.com,
        lokeshgidra@...gle.com, david@...hat.com, hughd@...gle.com,
        mhocko@...e.com, axelrasmussen@...gle.com, rppt@...nel.org,
        willy@...radead.org, Liam.Howlett@...cle.com, jannh@...gle.com,
        zhangpeng362@...wei.com, bgeffon@...gle.com,
        kaleshsingh@...gle.com, ngeoffray@...gle.com, jdduke@...gle.com,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH v4 5/5] selftests/mm: add UFFDIO_MOVE ioctl test

On Mon, Oct 30, 2023 at 01:22:02PM -0700, Suren Baghdasaryan wrote:
> > > +static int adjust_page_size(void)
> > > +{
> > > +     page_size = default_huge_page_size();
> >
> > This is hacky too, currently page_size is the real page_size backing the
> > memory.
> >
> > To make thp test simple, maybe just add one more test to MOVE a large chunk
> > to replace the thp test, which may contain a few thps?  It also doesn't
> > need to be fault based.
> 
> Sorry, I didn't get your suggestion. Could you please clarify? Which
> thp test are you referring to?

The new "move-pmd" test.

I meant maybe it makes sense to have one separate MOVE test for when one
ioctl(MOVE) covers a large range which can cover some thps.  Then that will
trigger thp paths.  Assuming the fault paths are already covered in the
generic "move" test.

Thanks,

-- 
Peter Xu