From: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
commit 8644772637deb121f7ac2df690cbf83fa63d3b70 upstream.
This patch replaces the size + 1 value introduced with the recent fix for 1
byte allocs with a constant value.
The idea here is to reduce code overhead as the previous logic would have
to read size into a register, then increment it, and write it back to
whatever field was being used. By using a constant we can avoid those
memory reads and arithmetic operations in favor of just encoding the
maximum value into the operation itself.
Fixes: 2c2ade81741c ("mm: page_alloc: fix ref bias in page_frag_alloc() for 1-byte allocs")
Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3955,11 +3955,11 @@ refill:
/* Even if we own the page, we do not use atomic_set().
* This would break get_page_unless_zero() users.
*/
- page_ref_add(page, size);
+ page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);
/* reset page count bias and offset to start of new frag */
nc->pfmemalloc = page_is_pfmemalloc(page);
- nc->pagecnt_bias = size + 1;
+ nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
nc->offset = size;
}
@@ -3975,10 +3975,10 @@ refill:
size = nc->size;
#endif
/* OK, page count is 0, we can safely set it */
- set_page_count(page, size + 1);
+ set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);
/* reset page count bias and offset to start of new frag */
- nc->pagecnt_bias = size + 1;
+ nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
offset = size - fragsz;
}
