linux-kernel - [PATCH v1 0/2] mm/hugetlb: fix write-fault handling for shared mappings

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Message-Id: <20220805110329.80540-1-david@redhat.com>
Date:   Fri,  5 Aug 2022 13:03:27 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Peter Xu <peterx@...hat.com>,
        Peter Feiner <pfeiner@...gle.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH v1 0/2] mm/hugetlb: fix write-fault handling for shared mappings

I observed that hugetlb does not support/expect write-faults in shared
mappings that would have to map the R/O-mapped page writable -- and I
found one case where we could currently get such faults and would
erroneously map an anon page into a shared mapping, by triggering
clear_refs to clear soft-dirty tracking at the wrong point in time on a
process.

I propose to backport the fix to stable trees, as the fix for write-notify
should be straight forward.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Muchun Song <songmuchun@...edance.com>
Cc: Peter Xu <peterx@...hat.com>
Cc: Peter Feiner <pfeiner@...gle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

David Hildenbrand (2):
  mm/hugetlb: fix hugetlb not supporting write-notify
  mm/hugetlb: support write-faults in shared mappings

 mm/hugetlb.c | 21 ++++++++++++++-------
 mm/mmap.c    |  7 +++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

-- 
2.35.3