min_order_for_split() returns -EBUSY when the folio is truncated and cannot be split. In commit 77008e1b2ef7 ("mm/huge_memory: do not change split_huge_page*() target order silently"), memory_failure() does not handle it and pass -EBUSY to try_to_split_thp_page() directly. try_to_split_thp_page() returns -EINVAL since -EBUSY becomes 0xfffffff0 as new_order is unsigned int in __folio_split() and this large new_order is rejected as an invalid input. The code does not cause a bug. soft_offline_in_use_page() also uses min_order_for_split() but it always passes 0 as new_order for split. Handle it properly by checking min_order_for_split() return value and not calling try_to_split_thp_page() if the value is negative. Add a comment in soft_offline_in_use_page() to clarify the possible negative new_order value. Signed-off-by: Zi Yan --- mm/memory-failure.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 7f908ad795ad..86582f030159 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2437,8 +2437,11 @@ int memory_failure(unsigned long pfn, int flags) * or unhandlable page. The refcount is bumped iff the * page is a valid handlable page. */ - folio_set_has_hwpoisoned(folio); - err = try_to_split_thp_page(p, new_order, /* release= */ false); + if (new_order >= 0) { + folio_set_has_hwpoisoned(folio); + err = try_to_split_thp_page(p, new_order, /* release= */ false); + } else + err = new_order; /* * If splitting a folio to order-0 fails, kill the process. * Split the folio regardless to minimize unusable pages. @@ -2779,6 +2782,7 @@ static int soft_offline_in_use_page(struct page *page) /* * If new_order (target split order) is not 0, do not split the * folio at all to retain the still accessible large folio. + * new_order can be -EBUSY, meaning the folio cannot be split. * NOTE: if minimizing the number of soft offline pages is * preferred, split it to non-zero new_order like it is done in * memory_failure(). -- 2.51.0