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

From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, David Hildenbrand <david@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Peter Xu <peterx@redhat.com>, Peter Feiner <pfeiner@google.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH v1 0/2] mm/hugetlb: fix write-fault handling for shared mappings
Date: Fri,  5 Aug 2022 13:03:27 +0200	[thread overview]
Message-ID: <20220805110329.80540-1-david@redhat.com> (raw)

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@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.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