From: Andrew Morton <akpm@linux-foundation.org>
To: Peter Xu <peterx@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Mika Penttilä" <mpenttil@redhat.com>,
"Axel Rasmussen" <axelrasmussen@google.com>,
"Nadav Amit" <nadav.amit@gmail.com>,
"David Hildenbrand" <david@redhat.com>,
linux-stable <stable@vger.kernel.org>
Subject: Re: [PATCH v2 2/6] mm/hugetlb: Fix uffd-wp bit lost when unsharing happens
Date: Mon, 17 Apr 2023 16:48:22 -0700 [thread overview]
Message-ID: <20230417164822.d1f5d162115c53aab4c85e85@linux-foundation.org> (raw)
In-Reply-To: <20230417195317.898696-3-peterx@redhat.com>
On Mon, 17 Apr 2023 15:53:13 -0400 Peter Xu <peterx@redhat.com> wrote:
> When we try to unshare a pinned page for a private hugetlb, uffd-wp bit can
> get lost during unsharing. Fix it by carrying it over.
>
> This should be very rare, only if an unsharing happened on a private
> hugetlb page with uffd-wp protected (e.g. in a child which shares the same
> page with parent with UFFD_FEATURE_EVENT_FORK enabled).
What are the user-visible consequences of the bug?
> Cc: linux-stable <stable@vger.kernel.org>
When proposing a backport, it's better to present the patch as a
standalone thing, against current -linus. I'll then queue it in
mm-hotfixes and shall send it upstream during this -rc cycle.
As presented, this patch won't go upstream until after 6.3 is released,
and as it comes later in time, more backporting effort might be needed.
I can rework things if this fix is reasonably urgent (the "user-visible
consequences" info is the guide). If not urgent, we can leave things
as they are.
next prev parent reply other threads:[~2023-04-17 23:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-17 19:53 [PATCH v2 0/6] mm/hugetlb: More fixes around uffd-wp vs fork() / RO pins Peter Xu
2023-04-17 19:53 ` [PATCH v2 1/6] mm/hugetlb: Fix uffd-wp during fork() Peter Xu
2023-04-17 19:53 ` [PATCH v2 2/6] mm/hugetlb: Fix uffd-wp bit lost when unsharing happens Peter Xu
2023-04-17 23:48 ` Andrew Morton [this message]
2023-04-18 15:14 ` Peter Xu
2023-04-17 19:53 ` [PATCH v2 3/6] selftests/mm: Add a few options for uffd-unit-test Peter Xu
2023-04-18 16:08 ` David Hildenbrand
2023-04-17 19:53 ` [PATCH v2 4/6] selftests/mm: Extend and rename uffd pagemap test Peter Xu
2023-04-17 19:53 ` [PATCH v2 5/6] selftests/mm: Rename COW_EXTRA_LIBS to IOURING_EXTRA_LIBS Peter Xu
2023-04-17 19:53 ` [PATCH v2 6/6] selftests/mm: Add tests for RO pinning vs fork() Peter Xu
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