Commit 773b9a6a authored by Ma Wupeng's avatar Ma Wupeng Committed by Andrew Morton
Browse files

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: default avatarMa Wupeng <mawupeng1@huawei.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b81679b1

mm/memory_hotplug.c

+7 −13
Original line number Diff line number Diff line
@@ -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)) {