On Fri, May 22, 2026 at 09:00:06AM -0600, Nico Pache wrote:
[...]
>@@ -1587,10 +1749,11 @@ static enum scan_result collapse_scan_pmd(struct
>mm_struct *mm,
> if (result == SCAN_SUCCEED) {
> /* collapse_huge_page expects the lock to be dropped before
> calling */
> mmap_read_unlock(mm);
>- result = collapse_huge_page(mm, start_addr, referenced,
>- unmapped, cc, HPAGE_PMD_ORDER);
>- /* collapse_huge_page will return with the mmap_lock released */
>+ nr_collapsed = mthp_collapse(mm, vma, start_addr, referenced,
>+ unmapped, cc, enabled_orders);
>+ /* mmap_lock was released above, set lock_dropped */
> *lock_dropped = true;
>+ result = nr_collapsed ? SCAN_SUCCEED : SCAN_FAIL;
Hmm ... don't we lose the allocation-failure result here?
Previously collapse_scan_pmd() propagated SCAN_ALLOC_HUGE_PAGE_FAIL from
collapse_huge_page(), so khugepaged would call khugepaged_alloc_sleep()
in khugepaged_do_scan().
Now if allocation fails and nr_collapsed stays 0, we just return
SCAN_FAIL. So we won't back off via khugepaged_alloc_sleep() anymore?
Cheers, Lance
