From 773b9a6aa6d38894b95088e3ed6f8a701d9f50fd Mon Sep 17 00:00:00 2001 From: Ma Wupeng Date: Mon, 17 Feb 2025 09:43:28 +0800 Subject: [PATCH] mm: memory-hotplug: check folio ref count first in do_migrate_range If a folio has an increased reference count, folio_try_get() will acquire it, perform necessary operations, and then release it. In the case of a poisoned folio without an elevated reference count (which is unlikely for memory-failure), folio_try_get() will simply bypass it. Therefore, relocate the folio_try_get() function, responsible for checking and acquiring this reference count at first. Link: https://lkml.kernel.org/r/20250217014329.3610326-3-mawupeng1@huawei.com Signed-off-by: Ma Wupeng Acked-by: David Hildenbrand Acked-by: Miaohe Lin Cc: Michal Hocko Cc: Naoya Horiguchi Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton --- mm/memory_hotplug.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index e7e47838fd49..a6abd8d4a09c 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1822,12 +1822,12 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) if (folio_test_large(folio)) pfn = folio_pfn(folio) + folio_nr_pages(folio) - 1; - /* - * HWPoison pages have elevated reference counts so the migration would - * fail on them. It also doesn't make any sense to migrate them in the - * first place. Still try to unmap such a page in case it is still mapped - * (keep the unmap as the catch all safety net). - */ + if (!folio_try_get(folio)) + continue; + + if (unlikely(page_folio(page) != folio)) + goto put_folio; + if (folio_test_hwpoison(folio) || (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) { if (WARN_ON(folio_test_lru(folio))) @@ -1835,14 +1835,8 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) if (folio_mapped(folio)) unmap_poisoned_folio(folio, pfn, false); - continue; - } - - if (!folio_try_get(folio)) - continue; - - if (unlikely(page_folio(page) != folio)) goto put_folio; + } if (!isolate_folio_to_list(folio, &source)) { if (__ratelimit(&migrate_rs)) {