path: root/mm
diff options
authorJeremy Fitzhardinge <jeremy@goop.org>2007-10-05 17:19:35 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-06 09:31:30 -0700
commit67dd5a25f4efbfccf973159429cb20acdc5b0e0e (patch)
tree9965b12c0d614b7cf82dd8483cfc1671f925af4e /mm
parent9f34073b4e54ad58541e0e2b4a87f4f6c1460e21 (diff)
xen: disable split pte locks for now
When pinning and unpinning pagetables, we must protect them against being used by other CPUs, lest they see the pagetable in an intermediate read-only-but-not-pinned state. When using split pte locks, doing this properly would require taking all the pte locks for the pagetable while pinning, but this may overflow the PREEMPT_BITS part of the preempt counter if the process has mapped more than about 512M of memory. However, failing to take the pte locks causes write-protect faults when the pageout code is trying to clear the Access bit on a pte which is part of a freshy created and still being pinned process after fork. This is a short-term fix until the problem is solved properly. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andi Kleen <ak@suse.de> Cc: Keir Fraser <keir@xensource.com> Cc: Jan Beulich <jbeulich@novell.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index e24d348083c..a7609cbcb00 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -137,6 +137,7 @@ config SPLIT_PTLOCK_CPUS
default "4096" if ARM && !CPU_CACHE_VIPT
default "4096" if PARISC && !PA20
+ default "4096" if XEN
default "4"