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A second registration returns >> -EBUSY, and only the active migrator can stop itself. The static_call >> dispatch is under SRCU so synchronize_srcu() in stop path guarantees >> no in-flight copy before the module reference is dropped. >> > ... snip ... > >> @@ -1820,11 +1833,18 @@ static int migrate_pages_batch(struct list_head *from, >> >> +#ifdef CONFIG_MIGRATION_COPY_OFFLOAD >> + /* Check if the offload driver wants to batch for this reason */ >> + if (static_branch_unlikely(&migrate_offload_enabled)) >> + do_batch = static_call(migrate_should_batch)(reason); >> +#endif >> + > > should the migrate_should_batch call also be done under srcu? > > In theory it's an incredibly small window, but there is a race window. Yes, right. thanks for pointing this out. Best regards, Shivank