Revert "[PATCH] mm: micro optimise zone_watermark_ok"

This reverts commit e80ee884ae0e3794ef2b65a18a767d502ad712ee.

Pawel Sikora had a boot-time oops due to it - because the sign change
invalidates the following comparisons, since 'free_pages' can be
negative.

The micro-optimization just isn't worth it.

Bisected-by: Pawel Sikora <pluto@agmk.net>
Acked-by: Andrew Morton <akpm@osdl.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fc5b544..2c606cc 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -989,8 +989,7 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
                      int classzone_idx, int alloc_flags)
 {
        /* free_pages my go negative - that's OK */
-       unsigned long min = mark;
-       long free_pages = z->free_pages - (1 << order) + 1;
+       long min = mark, free_pages = z->free_pages - (1 << order) + 1;
        int o;
 
        if (alloc_flags & ALLOC_HIGH)