On 06/28/2012 08:55 AM, Andrea Arcangeli wrote:
gup_fast will skip over non present ptes (pte_numa requires the pte to be non present). So no explicit check is needed for pte_numa in the pte case. gup_fast will also automatically skip over THP when the trans huge pmd is non present (pmd_numa requires the pmd to be non present). But for the special pmd mode scan of knuma_scand (/sys/kernel/mm/autonuma/knuma_scand/pmd == 1), the pmd may be of numa type (so non present too), the pte may be present. gup_pte_range wouldn't notice the pmd is of numa type. So to avoid losing a NUMA hinting page fault with gup_fast we need an explicit check for pmd_numa() here to be sure it will fault through gup -> handle_mm_fault. Signed-off-by: Andrea Arcangeli<aarcange@xxxxxxxxxx>
Assuming pmd_numa will get the documentation I asked for a few patches back, this patch is fine, since people will just be able to look at a nice comment above pmd_numa and see what is going on. Acked-by: Rik van Riel <riel@xxxxxxxxxx> -- All rights reversed -- 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>