On 8/25/2022 3:10 PM, David Hildenbrand wrote:
+ /*
+ * 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).
Make sense. Thanks for your explanation.
