Messages in this thread Patch in this message | | | From | Liang Chen <> | Subject | [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY | Date | Thu, 7 Jan 2016 11:52:38 +0800 |
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MPOL_MF_LAZY is not visible from userspace since 'commit a720094ded8c ("mm: mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now")' , but it should still skip non-migratable VMAs such as VM_IO, VM_PFNMAP, and VM_HUGETLB VMAs, and avoid useless overhead of minor faults.
Signed-off-by: Liang Chen <liangchen.linux@gmail.com> Signed-off-by: Gavin Guo <gavin.guo@canonical.com> --- Changes since v2: - Add more description into the changelog
We have been evaluating the enablement of MPOL_MF_LAZY again, and found this issue. And we decided to push this patch upstream no matter if we finally determine to propose re-enablement of MPOL_MF_LAZY or not. Since it can be a potential problem even if MPOL_MF_LAZY is not enabled this time. --- mm/mempolicy.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 87a1779..436ff411 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -610,7 +610,8 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end, if (flags & MPOL_MF_LAZY) { /* Similar to task_numa_work, skip inaccessible VMAs */ - if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) + if (vma_migratable(vma) && + vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) change_prot_numa(vma, start, endvma); return 1; } -- 1.9.1
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