On 2025/4/29 02:12, Nico Pache wrote:
There are cases where, if an attempted collapse fails, all subsequent orders are guaranteed to also fail. Avoid these collapse attempts by bailing out early. Signed-off-by: Nico Pache <[email protected]> --- mm/khugepaged.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 86d1153ce9e8..5e6732cccb86 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1365,6 +1365,23 @@ static int khugepaged_scan_bitmap(struct mm_struct *mm, unsigned long address, collapsed += (1 << order); continue; } + /* + * Some ret values indicate all lower order will also + * fail, dont trying to collapse smaller orders + */ + if (ret == SCAN_EXCEED_NONE_PTE || + ret == SCAN_EXCEED_SWAP_PTE || + ret == SCAN_EXCEED_SHARED_PTE || + ret == SCAN_PTE_NON_PRESENT || + ret == SCAN_PTE_UFFD_WP || + ret == SCAN_ALLOC_HUGE_PAGE_FAIL || + ret == SCAN_CGROUP_CHARGE_FAIL || + ret == SCAN_COPY_MC || + ret == SCAN_PAGE_LOCK || + ret == SCAN_PAGE_COUNT) + goto next; + else + break;
Better to merge this patch into patch 6, which can be helped to understand your logic.
