On Wed, 20 Sep 2023 15:32:42 -0700 Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx> wrote: > When calling mbind() with MPOL_MF_{MOVE|MOVEALL} | MPOL_MF_STRICT, > kernel should attempt to migrate all existing pages, and return -EIO if > there is misplaced or unmovable page. Then commit 6f4576e3687b > ("mempolicy: apply page table walker on queue_pages_range()") messed up > the return value and didn't break VMA scan early ianymore when MPOL_MF_STRICT > alone. The return value problem was fixed by commit a7f40cfe3b7a > ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified"), > but it broke the VMA walk early if unmovable page is met, it may cause some > pages are not migrated as expected. So I'm thinking that a7f40cfe3b7a is the suitable Fixes: target? > The code should conceptually do: > > if (MPOL_MF_MOVE|MOVEALL) > scan all vmas > try to migrate the existing pages > return success > else if (MPOL_MF_MOVE* | MPOL_MF_STRICT) > scan all vmas > try to migrate the existing pages > return -EIO if unmovable or migration failed > else /* MPOL_MF_STRICT alone */ > break early if meets unmovable and don't call mbind_range() at all > else /* none of those flags */ > check the ranges in test_walk, EFAULT without mbind_range() if discontig. > > Fixed the behavior. >