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| Started by | Liang Chen <liangchen.linux@gmail.com> |
|---|---|
| First post | 2016-01-07 05:00 +0100 |
| Last post | 2016-01-15 14:00 +0100 |
| Articles | 3 — 2 participants |
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[PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY Liang Chen <liangchen.linux@gmail.com> - 2016-01-07 05:00 +0100
Re: [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-01-13 09:20 +0100
Re: [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY Liang Chen <liangchen.linux@gmail.com> - 2016-01-15 14:00 +0100
| From | Liang Chen <liangchen.linux@gmail.com> |
|---|---|
| Date | 2016-01-07 05:00 +0100 |
| Subject | [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY |
| Message-ID | <qO9TX-2mQ-1@gated-at.bofh.it> |
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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| From | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
|---|---|
| Date | 2016-01-13 09:20 +0100 |
| Subject | Re: [PATCH V2] mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY |
| Message-ID | <qQoOT-5ih-25@gated-at.bofh.it> |
| In reply to | #1303267 |
Hello Liang,
On Thu, Jan 07, 2016 at 11:52:38AM +0800, Liang Chen wrote:
> 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;
> }
task_numa_work() does more vma checks before entering change_prot_numa() like
vma_policy_mof(), is_vm_hugetlb_page(), and (vma->vm_flags & VM_MIXEDMAP).
So is it better to use the same check set to limit the target vmas to auto-numa
enabled ones?
Thanks,
Naoya Horiguchi
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| From | Liang Chen <liangchen.linux@gmail.com> |
|---|---|
| Date | 2016-01-15 14:00 +0100 |
| Message-ID | <qRc8W-6ca-7@gated-at.bofh.it> |
| In reply to | #1308155 |
Hi Naoya,
Yeah. Thanks for the remindingļ¼
vma_policy_mof doesn't need to be checked because with MPOL_MF_LAZY
do_mbind always sets the MPOL_F_MOF flag.
VM_HUGETLB and VM_MIXEDMAP vma should be excluded to avoid compound
pages being marked for migration and unexpected COWs when handling
hugetlb fault.
I will send a patch to add these check soon.
Thanks,
Liang
On Wed, Jan 13, 2016 at 4:16 PM, Naoya Horiguchi
<n-horiguchi@ah.jp.nec.com> wrote:
> Hello Liang,
>
> On Thu, Jan 07, 2016 at 11:52:38AM +0800, Liang Chen wrote:
>> 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;
>> }
>
> task_numa_work() does more vma checks before entering change_prot_numa() like
> vma_policy_mof(), is_vm_hugetlb_page(), and (vma->vm_flags & VM_MIXEDMAP).
> So is it better to use the same check set to limit the target vmas to auto-numa
> enabled ones?
>
> Thanks,
> Naoya Horiguchi
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