From: David Hildenbrand <david@redhat.com>
To: Peter Xu <peterx@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
Nadav Amit <nadav.amit@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
James Houghton <jthoughton@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 0/3] mm/uffd: Fix missing markers on hugetlb
Date: Thu, 5 Jan 2023 09:16:43 +0100 [thread overview]
Message-ID: <b6b428a9-f411-a813-0f9f-11b7b57f64c1@redhat.com> (raw)
In-Reply-To: <20230104225207.1066932-1-peterx@redhat.com>
On 04.01.23 23:52, Peter Xu wrote:
> When James was developing the vma split fix for hugetlb pmd sharing, he
> found that hugetlb uffd-wp is broken with the test case he developed [1]:
>
> https://lore.kernel.org/r/CADrL8HWSym93=yNpTUdWebOEzUOTR2ffbfUk04XdK6O+PNJNoA@mail.gmail.com
>
> Missing hugetlb pgtable pages caused uffd-wp to lose message when vma split
> happens to be across a shared huge pmd range in the test.
>
> The issue is pgtable pre-allocation on hugetlb path was overlooked. That
> was fixed in patch 1.
Nice timing, I stumbled over that while adjusting background snapshot
code in QEMU and wondered why we are not allocating page tables in that
case -- and wanted to ask you why :)
--
Thanks,
David / dhildenb
prev parent reply other threads:[~2023-01-05 8:16 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-04 22:52 Peter Xu
2023-01-04 22:52 ` [PATCH 1/3] mm/hugetlb: Pre-allocate pgtable pages for uffd wr-protects Peter Xu
2023-01-05 1:50 ` James Houghton
2023-01-05 8:39 ` David Hildenbrand
2023-01-05 18:37 ` Mike Kravetz
2023-01-04 22:52 ` [PATCH 2/3] mm/mprotect: Use long for page accountings and retval Peter Xu
2023-01-05 1:51 ` James Houghton
2023-01-05 8:44 ` David Hildenbrand
2023-01-05 19:22 ` Peter Xu
2023-01-09 8:04 ` David Hildenbrand
2023-01-05 18:48 ` Mike Kravetz
2023-01-04 22:52 ` [PATCH 3/3] mm/uffd: Detect pgtable allocation failures Peter Xu
2023-01-05 1:52 ` James Houghton
2023-01-05 3:10 ` Nadav Amit
2023-01-05 8:59 ` David Hildenbrand
2023-01-05 18:01 ` Nadav Amit
2023-01-05 19:51 ` Peter Xu
2023-01-18 21:51 ` Nadav Amit
2023-01-09 8:36 ` David Hildenbrand
2023-01-05 8:47 ` David Hildenbrand
2023-01-05 8:16 ` David Hildenbrand [this message]
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