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authorJeremy Fitzhardinge <jeremy@xensource.com>2007-10-16 11:51:30 -0700
committerJeremy Fitzhardinge <jeremy@goop.org>2007-10-16 11:51:30 -0700
commit74260714c56de4f967fcb2f17a8656bc574b75be (patch)
treef02bcd991285a20a543fae69f916577c8447b8f4 /mm/Kconfig
parent9f79991d4186089e228274196413572cc000143b (diff)
downloadconfigs-74260714c56de4f967fcb2f17a8656bc574b75be.tar.gz
xen: lock pte pages while pinning/unpinning
When a pagetable is created, it is made globally visible in the rmap prio tree before it is pinned via arch_dup_mmap(), and remains in the rmap tree while it is unpinned with arch_exit_mmap(). This means that other CPUs may race with the pinning/unpinning process, and see a pte between when it gets marked RO and actually pinned, causing any pte updates to fail with write-protect faults. As a result, all pte pages must be properly locked, and only unlocked once the pinning/unpinning process has finished. In order to avoid taking spinlocks for the whole pagetable - which may overflow the PREEMPT_BITS portion of preempt counter - it locks and pins each pte page individually, and then finally pins the whole pagetable. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickens <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>
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig1
1 files changed, 0 insertions, 1 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index a7609cbcb00..e24d348083c 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -137,7 +137,6 @@ config SPLIT_PTLOCK_CPUS
int
default "4096" if ARM && !CPU_CACHE_VIPT
default "4096" if PARISC && !PA20
- default "4096" if XEN
default "4"
#