Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=67dd5a25f4efbfccf973159429cb20acdc5b0e0e
Commit:     67dd5a25f4efbfccf973159429cb20acdc5b0e0e
Parent:     9f34073b4e54ad58541e0e2b4a87f4f6c1460e21
Author:     Jeremy Fitzhardinge <[EMAIL PROTECTED]>
AuthorDate: Fri Oct 5 17:19:35 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Sat Oct 6 09:31:30 2007 -0700

    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 <[EMAIL PROTECTED]>
    Acked-by: Rik van Riel <[EMAIL PROTECTED]>
    Acked-by: Hugh Dickins <[EMAIL PROTECTED]>
    Cc: David Rientjes <[EMAIL PROTECTED]>
    Cc: Andrew Morton <[EMAIL PROTECTED]>
    Cc: Andi Kleen <[EMAIL PROTECTED]>
    Cc: Keir Fraser <[EMAIL PROTECTED]>
    Cc: Jan Beulich <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 mm/Kconfig |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index e24d348..a7609cb 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -137,6 +137,7 @@ config SPLIT_PTLOCK_CPUS
        int
        default "4096" if ARM && !CPU_CACHE_VIPT
        default "4096" if PARISC && !PA20
+       default "4096" if XEN
        default "4"
 
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