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mm: memory-hotplug: check folio ref count first in do_migrate_range

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commit 773b9a6aa6d38894b95088e3ed6f8a701d9f50fd upstream.

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 <mawupeng1@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Miaohe 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ma Wupeng
2025-02-17 09:43:28 +08:00
committed by Greg Kroah-Hartman
parent 576a2f4c43
commit 2e66d69941
1 changed files with 7 additions and 13 deletions
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20
mm/memory_hotplug.c
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@@ -1795,12 +1795,12 @@ 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)))
@@ -1811,14 +1811,8 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
folio_unlock(folio);
}
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)) {