Hi all, When I setup two zones (NORMAL and DMA) in my system, I got the following wired result from /proc/buddyinfo. ----------------------------------------------------------------------------------------- root:~> cat /proc/buddyinfo Node 0, zone DMA 2 1 2 1 1 0 0 1 1 2 2 0 0 0 Node 0, zone Normal 1 1 1 1 1 1 0 0 4294967295 0 4294967295 2 0 0 -----------------------------------------------------------------------------------------
As you see, two area->nr_free went -1. After dig into the code, I found the problem is in the fun __free_one_page() when the kernel boot up call free_all_bootmem(). If two zones setup, it's possible NORMAL zone merged a block whose order =8 at the first time(this time zone[NORMA]->free_area[8].nr_free = 0) and found its buddy in the DMA zone. So the two blocks will be merged and area->nr_free went to -1. My proposed patch is as follows: Signed-off-by: Aubrey Li <[EMAIL PROTECTED]> --------------------------------------------------------------------------------------------------- --- page_alloc.c.orig 2006-12-19 10:45:25.000000000 +0800 +++ page_alloc.c 2006-12-19 10:44:48.000000000 +0800 @@ -407,7 +407,8 @@ static inline void __free_one_page(struc list_del(&buddy->lru); area = zone->free_area + order; - area->nr_free--; + if (area->nr_free > 0) + area->nr_free--; rmv_page_order(buddy); combined_idx = __find_combined_index(page_idx, order); page = page + (combined_idx - page_idx); ---------------------------------------------------------------------------------------------------- Any comments? Thanks, -Aubrey - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/