From 44af0b45d58d7b6f09ebb9081aa89b8bdc33a630 Mon Sep 17 00:00:00 2001 From: Alistair Popple Date: Fri, 11 Nov 2022 11:51:35 +1100 Subject: [PATCH] mm/migrate_device: return number of migrating pages in args->cpages migrate_vma->cpages originally contained a count of the number of pages migrating including non-present pages which can be populated directly on the target. Commit 241f68859656 ("mm/migrate_device.c: refactor migrate_vma and migrate_device_coherent_page()") inadvertantly changed this to contain just the number of pages that were unmapped. Usage of migrate_vma->cpages isn't documented, but most drivers use it to see if all the requested addresses can be migrated so restore the original behaviour. Link: https://lkml.kernel.org/r/20221111005135.1344004-1-apopple@nvidia.com Fixes: 241f68859656 ("mm/migrate_device.c: refactor migrate_vma and migrate_deivce_coherent_page()") Signed-off-by: Alistair Popple Reported-by: Ralph Campbell Reviewed-by: Ralph Campbell Cc: John Hubbard Cc: Alex Sierra Cc: Ben Skeggs Cc: Felix Kuehling Cc: Lyude Paul Cc: Jason Gunthorpe Cc: Michael Ellerman Signed-off-by: Andrew Morton --- mm/migrate_device.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 6fa682eef7a0..721b2365dbca 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -357,7 +357,8 @@ static bool migrate_vma_check_page(struct page *page, struct page *fault_page) } /* - * Unmaps pages for migration. Returns number of unmapped pages. + * Unmaps pages for migration. Returns number of source pfns marked as + * migrating. */ static unsigned long migrate_device_unmap(unsigned long *src_pfns, unsigned long npages, @@ -373,8 +374,11 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns, struct page *page = migrate_pfn_to_page(src_pfns[i]); struct folio *folio; - if (!page) + if (!page) { + if (src_pfns[i] & MIGRATE_PFN_MIGRATE) + unmapped++; continue; + } /* ZONE_DEVICE pages are not on LRU */ if (!is_zone_device_page(page)) {