tree 99fbeeeb8881725fe7f8eeb7455f365cf9c6fc60
parent eef5de94700031e4968ff8f5030a54c3b52207d3
author Kirill A. Shutemov <kirill.shutemov@linux.intel.com> 1481258796 +0800
committer Teemu Hukkanen <teemu@fairphone.com> 1485724823 +0100

FPII-2702:mm: avoid setting up anonymous pages into file mapping

Reading page fault handler code I've noticed that under right
circumstances kernel would map anonymous pages into file mappings: if
the VMA doesn't have vm_ops->fault() and the VMA wasn't fully populated
on ->mmap(), kernel would handle page fault to not populated pte with
do_anonymous_page().

Let's change page fault handler to use do_anonymous_page() only on
anonymous VMA (->vm_ops == NULL) and make sure that the VMA is not
shared.

For file mappings without vm_ops->fault() or shred VMA without vm_ops,
page fault on pte_none() entry would lead to SIGBUS.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change-Id: Ie8aa23d9ced1811eeaf84b2528c4358d84cc4a6f