On Thu, Nov 28, 2024 at 07:12:11PM +0800, Huang, Ying wrote: > Hi, Gregory, > > Gregory Price <gourry@xxxxxxxxxx> writes: > > > To migrate unmapped pagecache folios, migrate_misplaced_folio and > > migrate_misplaced_folio_prepare must handle folios without VMAs. > > IMHO, it's better to use migrate_misplaced_folio() instead of > migrate_misplaced_folio for readability in patch title and description. > > > migrate_misplaced_folio_prepare checks VMA for exec bits, so allow > > a NULL VMA when it does not have a mapping. > > > > migrate_misplaced_folio must call migrate_pages with MIGRATE_SYNC > > when in the pagecache path because it is a synchronous context. > > I don't find the corresponding implementation for this. And, I don't > think it's a good idea to change from MIGRATE_ASYNC to MIGRATE_SYNC. > This may cause too long page access latency for page placement > optimization. The downside may offset the benefit. > > And, it appears that we can delete the "vma" parameter of > migrate_misplaced_folio() because it's not used now. This is a trivial > code cleanup. > This patch apparently got a bit away from me and was heavily reduced from its initial form. This commit message is just wrong now. I will update this and the 2nd commit and probably submit them separately. ~Gregory
