Messages in this thread Patch in this message | | | Date | Mon, 16 Dec 2013 18:15:13 -0500 | From | Rik van Riel <> | Subject | [PATCH 19/18] mm,numa: write pte_numa pte back to the page tables |
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On Tue, 10 Dec 2013 15:51:23 +0000 Mel Gorman <mgorman@suse.de> wrote:
> The TLB must be flushed if the PTE is updated but change_pte_range is clearing > the PTE while marking PTEs pte_numa without necessarily flushing the TLB if it > reinserts the same entry. Without the flush, it's conceivable that two processors > have different TLBs for the same virtual address and at the very least it would > generate spurious faults. This patch only unmaps the pages in change_pte_range for > a full protection change.
Turns out the patch optimized out not one, but both pte writes. Oops.
We'll need this one too, Andrew :)
---8<---
Subject: mm,numa: write pte_numa pte back to the page tables
The patch "mm: numa: Do not clear PTE for pte_numa update" cleverly optimizes out an extraneous PTE write when changing the protection of pages to pte_numa.
It also optimizes out actually writing the new pte_numa entry back to the page tables. Oops.
Signed-off-by: Rik van Riel <riel@redhat.com> Reported-by: Chegu Vinod <chegu_vinod@hp.com> --- mm/mprotect.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c index edc4e22..4114acf 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -67,6 +67,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, if (page && !PageKsm(page)) { if (!pte_numa(oldpte)) { ptent = pte_mknuma(ptent); + set_pte_at(mm, addr, pte, ptent); updated = true; } }
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