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09:22:28AM +0530, Dev Jain wrote: > > > On 25/06/25 6:58 pm, Lorenzo Stoakes wrote: > > > > On Wed, Jun 25, 2025 at 11:28:06AM +0530, Dev Jain wrote: > > > > > Suppose a folio is under migration, and khugepaged is also trying to > > > > > collapse it. collapse_pte_mapped_thp() will retrieve the folio from the > > > > > page cache via filemap_lock_folio(), thus taking a reference on the folio > > > > > and sleeping on the folio lock, since the lock is held by the migration > > > > > path. Migration will then fail in > > > > > __folio_migrate_mapping -> folio_ref_freeze. Reduce the probability of > > > > > such a race happening (leading to migration failure) by bailing out > > > > > if we detect a PMD is marked with a migration entry. > > > > > > > > > > This fixes the migration-shared-anon-thp testcase failure on Apple M3. > > > > Hm is this related to the series at all? Seems somewhat unrelated? > > > Not related. > > > > > > > Is there a Fixes, Closes, etc.? Do we need something in stable? > > > We don't need anything. This is an "expected race" in the sense that > > > both migration and khugepaged collapse are best effort algorithms. > > > I am just seeing a test failure on my system because my system hits > > > the race more often. So this patch reduces the window for the race. > > Does it rely on previous patches? If not probably best to send this one > > separately :) > > To prevent rebasing headaches for others (if any) I thought to send all together. > I'll send it separately if still that is the preference. > > Oh actually would it be a pain to rebase given the previous 2 patches? Maybe leave it then. And I can actually finally review it... :)