mm/autonuma: don't use set_pte_at when updating protnone ptes
authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Fri, 24 Feb 2017 22:59:13 +0000 (14:59 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 25 Feb 2017 01:46:56 +0000 (17:46 -0800)
commitcee216a696b2004017a5ecb583366093d90b1568
tree4270e8e8e17a7450395e374b3a10391818d08d45
parent3f472cc978ea019c7b09cc03f90b8ed6034efdf8
mm/autonuma: don't use set_pte_at when updating protnone ptes

Architectures like ppc64, use privilege access bit to mark pte non
accessible.  This implies that kernel can do a copy_to_user to an
address marked for numa fault.  This also implies that there can be a
parallel hardware update for the pte.  set_pte_at cannot be used in such
scenarios.  Hence switch the pte update to use ptep_get_and_clear and
set_pte_at combination.

[akpm@linux-foundation.org: remove unwanted ppc change, per Aneesh]
Link: http://lkml.kernel.org/r/1486400776-28114-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory.c