On 1/15/20 1:30 PM, Yang Shi wrote: > On 1/15/20 1:07 PM, Mike Kravetz wrote: >> What should we do? >> ================== >> 1) Nothing more than optimizations by Li Xinhai. Behavior that could be >> seen as conflicting with man page has existed since v3.12 and I am >> not aware of any complaints. >> 2) In addition to optimizations by Li Xinhai, modify code to truly ignore >> MPOL_MF_STRICT for huge page mappings. This would be fairly easy to do >> after a failure of migrate_pages(). We could simply traverse the list >> of pages that were not migrated looking for any non-hugetlb page. > > I don't think we can do this easily since migrate_pages() would put the migration failed hugetlb pages back to hugepage_activelist so there should not any hugetlb page reside on the pagelist regardless of failure if I read the code correctly. > You are correct. I made an assumption without actually looking at the code. :( > Other than that traversing page list to look for a certain type page doesn't sound scalable to me. > >> 3) Remove the statement "MPOL_MF_STRICT is ignored on huge page mappings." >> and modify code accordingly. >> >> My suggestion would be for 1 or 2. Thoughts? > > By rethinking the history (thanks again for digging into it), it sounds #3 should be more reasonable. It sounds like the behavior was changed since hugetlb migration was added but the man page was not updated to reflect the change. > Let's hope Naoya comments. My only concern with #3 is that we will be changing behavior. I do not think many people (if any) depend on existing behavior. However, you can never be sure. -- Mike Kravetz
