From: Mel Gorman Date: Mon, 7 Oct 2013 10:29:14 +0000 (+0100) Subject: mm: numa: Trap pmd hinting faults only if we would otherwise trap PTE faults X-Git-Tag: upstream/snapshot3+hdmi~4037^2~54 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=25cbbef1924299249756bc4030fcb2436c019813;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git mm: numa: Trap pmd hinting faults only if we would otherwise trap PTE faults Base page PMD faulting is meant to batch handle NUMA hinting faults from PTEs. However, even is no PTE faults would ever be handled within a range the kernel still traps PMD hinting faults. This patch avoids the overhead. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Srikar Dronamraju Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1381141781-10992-37-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar --- diff --git a/mm/mprotect.c b/mm/mprotect.c index f0b087d..5aae390 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -146,6 +146,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pmd = pmd_offset(pud, addr); do { + unsigned long this_pages; + next = pmd_addr_end(addr, end); if (pmd_trans_huge(*pmd)) { if (next - addr != HPAGE_PMD_SIZE) @@ -165,8 +167,9 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, } if (pmd_none_or_clear_bad(pmd)) continue; - pages += change_pte_range(vma, pmd, addr, next, newprot, + this_pages = change_pte_range(vma, pmd, addr, next, newprot, dirty_accountable, prot_numa, &all_same_nidpid); + pages += this_pages; /* * If we are changing protections for NUMA hinting faults then @@ -174,7 +177,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, * node. This allows a regular PMD to be handled as one fault * and effectively batches the taking of the PTL */ - if (prot_numa && all_same_nidpid) + if (prot_numa && this_pages && all_same_nidpid) change_pmd_protnuma(vma->vm_mm, addr, pmd); } while (pmd++, addr = next, addr != end);