linux-kernel - Re: [PATCH] mm/userfaultfd: selftests: Fix memory corruption with thp enabled

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Date:   Mon, 27 Sep 2021 13:39:15 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Axel Rasmussen <axelrasmussen@...gle.com>
Cc:     Linux MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Nadav Amit <nadav.amit@...il.com>, Li Wang <liwan@...hat.com>
Subject: Re: [PATCH] mm/userfaultfd: selftests: Fix memory corruption with
 thp enabled

On Mon, Sep 27, 2021 at 10:34:06AM -0700, Axel Rasmussen wrote:
> One possibility would be to MADV_NOHUGEPAGE the regions, which at
> least would fix the immediate flakiness. Then we could spend some time
> adding a test case which specifically targets THP interactions? (I do
> think we want test coverage of that in the end, but with the current
> tests it's kind of "accidental".)

If we can't reproduce it with khugepaged yet, I'd think we can also consider
keep torturing thp with this patch and at the meantime look for a clean
approach?

Now it's only the event test failing, if we apply NOHUGEPAGE we give up thp for
all.

-- 
Peter Xu