From: Zi Yan <ziy@xxxxxxxxxx> Subject: mm: migrate: use thp_order instead of HPAGE_PMD_ORDER for new page allocation. Fix a VM_BUG_ON_FOLIO(folio_nr_pages(old) != nr_pages) crash. With folios support, it is possible to have other than HPAGE_PMD_ORDER THPs, in the form of folios, in the system. Use thp_order() to correctly determine the source page order during migration. Link: https://lkml.kernel.org/r/20220404165325.1883267-1-zi.yan@xxxxxxxx Link: https://lore.kernel.org/linux-mm/20220404132908.GA785673@u2004/ Fixes: d68eccad3706 ("mm/filemap: Allow large folios to be added to the page cache") Reported-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxxxx> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 2 +- mm/migrate.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/mm/mempolicy.c~mm-migrate-use-thp_order-instead-of-hpage_pmd_order-for-new-page-allocation +++ a/mm/mempolicy.c @@ -1209,7 +1209,7 @@ static struct page *new_page(struct page struct page *thp; thp = alloc_hugepage_vma(GFP_TRANSHUGE, vma, address, - HPAGE_PMD_ORDER); + thp_order(page)); if (!thp) return NULL; prep_transhuge_page(thp); --- a/mm/migrate.c~mm-migrate-use-thp_order-instead-of-hpage_pmd_order-for-new-page-allocation +++ a/mm/migrate.c @@ -1547,7 +1547,7 @@ struct page *alloc_migration_target(stru */ gfp_mask &= ~__GFP_RECLAIM; gfp_mask |= GFP_TRANSHUGE; - order = HPAGE_PMD_ORDER; + order = thp_order(page); } zidx = zone_idx(page_zone(page)); if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE) _
