From: Hui Zhu <zhuhui@xxxxxxxxxx> To test the patch [1], I use KGTP and a script [2] to show NR_FREE_CMA_PAGES and gross of cma_nr_free. The values are always not same. I check the code of pages alloc and free and found that race conditions on getting migratetype in buffered_rmqueue. Then I add move the code of getting migratetype inside the zone->lock protection part. Because this issue will affect system even if the Linux kernel does't have [1]. So I post this patch separately. This patchset is based on fc7f0dd381720ea5ee5818645f7d0e9dece41cb0. [1] https://lkml.org/lkml/2015/1/18/28 [2] https://github.com/teawater/kgtp/blob/dev/add-ons/cma_free.py Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx> --- mm/page_alloc.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7633c50..f3d6922 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1694,11 +1694,12 @@ again: } spin_lock_irqsave(&zone->lock, flags); page = __rmqueue(zone, order, migratetype); + if (page) + migratetype = get_pageblock_migratetype(page); + else + goto failed_unlock; spin_unlock(&zone->lock); - if (!page) - goto failed; - __mod_zone_freepage_state(zone, -(1 << order), - get_freepage_migratetype(page)); + __mod_zone_freepage_state(zone, -(1 << order), migratetype); } __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order)); @@ -1715,6 +1716,8 @@ again: goto again; return page; +failed_unlock: + spin_unlock(&zone->lock); failed: local_irq_restore(flags); return NULL; -- 1.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>