On Wed, 27 Sep 2023 14:39:21 -0700 Suren Baghdasaryan surenb@google.com wrote:
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.
With this change I think my temporary fix at https://lore.kernel.org/all/20230918211608.3580629-1-surenb@google.com/ can be removed because we either scan all vmas (which means we locked them all) or we break early and do not call mbind_range() at all (in which case we don't need vmas to be locked).
Thanks, I dropped "mm: lock VMAs skipped by a failed queue_pages_range()"