>> + /*
>> + * try_grab_page() should always succeed here, because we hold
>> + * the ptl lock and have verified pte_present().
>> + */
>> + if (WARN_ON_ONCE(!try_grab_page(page, flags))) {
>> + page = NULL;
>> + goto out;
>> + }
>> + } else {
>
> Should add FOLL_MIGRATION validation before waiting a migration entry.
We really only need FOLL_MIGRATION for KSM. As hugetlb pages cannot be
KSM pages, we don't need this.
Actually, I do have patches in the works that rip out FOLL_MIGRATION
completely by adjusting KSM code.
So let's try to not add dead code (although it would make sense for
feature completeness as is -- but then, FOLL_MIGRATION really needs to go).
--
Thanks,
David / dhildenb
