The patch titled
fix can_share_swap_page() when !CONFIG_SWAP
has been removed from the -mm tree. Its filename is
fix-can_share_swap_page-when-config_swap.patch
This patch was probably dropped from -mm because
it has now been merged into a subsystem tree or
into Linus's tree, or because it was folded into
its parent patch in the -mm tree.
From: Hua Zhong <hzhong@xxxxxxxxx>
can_share_swap_page() is used to check if the page has the last reference.
This avoids allocating a new page for COW if it's the last page.
However, if CONFIG_SWAP is not set, can_share_swap_page() is defined as 0,
thus always causes a copy for the last COW page. The below simple patch
fixes it.
Signed-off-by: Hua Zhong <hzhong@xxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/swap.h | 2 +-
1 files changed, 1 insertion(+), 1 deletion(-)
diff -puN include/linux/swap.h~fix-can_share_swap_page-when-config_swap include/linux/swap.h
--- devel/include/linux/swap.h~fix-can_share_swap_page-when-config_swap 2006-05-15 09:43:27.000000000 -0700
+++ devel-akpm/include/linux/swap.h 2006-05-15 09:43:27.000000000 -0700
@@ -296,7 +296,7 @@ static inline void disable_swap_token(vo
#define read_swap_cache_async(swp,vma,addr) NULL
#define lookup_swap_cache(swp) NULL
#define valid_swaphandles(swp, off) 0
-#define can_share_swap_page(p) 0
+#define can_share_swap_page(p) (page_mapcount(p) == 1)
#define move_to_swap_cache(p, swp) 1
#define move_from_swap_cache(p, i, m) 1
#define __delete_from_swap_cache(p) /*NOTHING*/
_
Patches currently in -mm which might be from hzhong@xxxxxxxxx are
origin.patch
likely-cleanup-remove-unlikely-in-sys_mprotect.patch
rename-swapper-to-idle.patch
remove-unlikely-in-might_sleep_if.patch
ide-error-handling-fixes.patch
profile-likely-unlikely-macros.patch
profile-likely-unlikely-macros-tidy.patch
profile-likely-unlikely-macros-fix.patch
profile-likely-unlikely-macros-fix-2.patch
fix-gcc-3x-w-likely-profiling.patch
-
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