From: Alexander Duyck alexander.h.duyck@linux.intel.com
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@linux.intel.com Signed-off-by: David S. Miller davem@davemloft.net Cc: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/page_alloc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4325,11 +4325,11 @@ 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; }
@@ -4345,10 +4345,10 @@ 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; }