[PATCHv5 01/11] mm: avoid increase sizeof(struct page) due to split page table lock

Kirill A. Shutemov
2013-10-07T13:56:34Z

CONFIG_GENERIC_LOCKBREAK increases sizeof(spinlock_t) to 8 bytes.
It leads to increase sizeof(struct page) by 4 bytes on 32-bit system if
split page table lock is in use, since page->ptl shares space in union
with longs and pointers.

Let's disable split page table lock on 32-bit systems with
GENERIC_LOCKBREAK enabled.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/Kconfig | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index 026771a9b0..6f5be0dac9 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -212,6 +212,7 @@ config SPLIT_PTLOCK_CPUS
default "999999" if ARM && !CPU_CACHE_VIPT
default "999999" if PARISC && !PA20
default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC
+ default "999999" if !64BIT && GENERIC_LOCKBREAK
default "4"

#
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1.8.4.rc3