[PATCH] Suppress split ptlock on arches which may use one page for multiple page tables

Suppress split ptlock on arches which may use one page for multiple page
tables.  Reconsider what better to do (particularly on ppc64) later on.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/Kconfig

@@ -126,9 +126,11 @@ comment "Memory hotplug is currently incompatible with Software Suspend"
 # Default to 4 for wider testing, though 8 might be more appropriate.
 # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
 # PA-RISC's debug spinlock_t is too large for the 32-bit struct page.
+# ARM26 and SPARC32 and PPC64 may use one page for multiple page tables.
 #
 config SPLIT_PTLOCK_CPUS
 	int
 	default "4096" if ARM && !CPU_CACHE_VIPT
 	default "4096" if PARISC && DEBUG_SPINLOCK && !64BIT
+	default "4096" if ARM26 || SPARC32 || PPC64
 	default "4"