On 1/14/20 6:09 AM, Li Xinhai wrote:
> Add cc to
> Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> , who has been worked on this part
>
> On 2020-01-14 at 17:16 Li Xinhai wrote:
>> Checking MPOL_MF_STRICT is ignored for HUGETLB vma according to mbind man
>> page:
>>
>> Notes
>> MPOL_MF_STRICT is ignored on huge page mappings.
>>
>> If MPOL_MF_STRICT is specified alone without any MOVE flag, we should
>> indicate, from test_walk, that walking this vma should be skipped even if
>> there are misplaced pages.
>>
>> Signed-off-by: Li Xinhai <lixinhai.lxh@xxxxxxxxx>
>> Cc: Michal Hocko <mhocko@xxxxxxxx>
>> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
I do not necessarily disagree with the change. However, this has made me
question a couple things:
1) Why does the man page say MPOL_MF_STRICT is ignored on huge page mappings?
- Is that leftover from the the days when huge page migration was not
supported?
- Is it just because huge page migration is more likely to fail than
base page migration.
2) Does the mbind code function properly when unable to migrate a huge page
MPOL_MF_STRICT is set? A quick look at the code looks like it returns
EIO.
I will look into these questions. However, if someone already knows the
answer that would be appreciated.
--
Mike Kravetz
