Changeset 7f1290f2f2 tries to fix a issue when calculating zone->present_pages, but it causes a regression to 32bit systems with HIGHMEM. With that changeset, function reset_zone_present_pages() resets all zone->present_pages to zero, and fixup_zone_present_pages() is called to recalculate zone->present_pages when boot allocator frees core memory pages into buddy allocator. Because highmem pages are not freed by bootmem allocator, all highmem zones' present_pages becomes zero.
Actually there's no need to recalculate present_pages for highmem zone because bootmem allocator never allocates pages from them. So fix the regression by skipping highmem in function reset_zone_present_pages() and fixup_zone_present_pages(). Signed-off-by: Jiang Liu <[email protected]> Signed-off-by: Jianguo Wu <[email protected]> Reported-by: Maciej Rutecki <[email protected]> Tested-by: Maciej Rutecki <[email protected]> Cc: Chris Clayton <[email protected]> Cc: Rafael J. Wysocki <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Minchan Kim <[email protected]> Cc: KAMEZAWA Hiroyuki <[email protected]> Cc: Michal Hocko <[email protected]> Cc: [email protected] Cc: [email protected] --- Hi Maciej, Thanks for reporting and bisecting. We have analyzed the regression and worked out a patch for it. Could you please help to verify whether it fix the regression? Thanks! Gerry --- mm/page_alloc.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 5b74de6..2311f15 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6108,7 +6108,8 @@ void reset_zone_present_pages(void) for_each_node_state(nid, N_HIGH_MEMORY) { for (i = 0; i < MAX_NR_ZONES; i++) { z = NODE_DATA(nid)->node_zones + i; - z->present_pages = 0; + if (!is_highmem(z)) + z->present_pages = 0; } } } @@ -6123,10 +6124,11 @@ void fixup_zone_present_pages(int nid, unsigned long start_pfn, for (i = 0; i < MAX_NR_ZONES; i++) { z = NODE_DATA(nid)->node_zones + i; + if (is_highmem(z)) + continue; + zone_start_pfn = z->zone_start_pfn; zone_end_pfn = zone_start_pfn + z->spanned_pages; - - /* if the two regions intersect */ if (!(zone_start_pfn >= end_pfn || zone_end_pfn <= start_pfn)) z->present_pages += min(end_pfn, zone_end_pfn) - max(start_pfn, zone_start_pfn); -- 1.7.1 -- 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/
