On 2025/1/16 14:16, Wupeng Ma wrote:
> From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
>
> 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.
>
> Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
> ---
> mm/memory_hotplug.c | 14 ++++----------
> 1 file changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 2815bd4ea483..3fb75ee185c6 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1786,6 +1786,9 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
> page = pfn_to_page(pfn);
> folio = page_folio(page);
>
> + if (!folio_try_get(folio))
> + continue;
> +
> /*
> * No reference or lock is held on the folio, so it might
> * be modified concurrently (e.g. split). As such,
> @@ -1795,12 +1798,6 @@ 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_test_hwpoison(folio) ||
> (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) {
> if (WARN_ON(folio_test_lru(folio)))
> @@ -1811,12 +1808,9 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
> folio_unlock(folio);
> }
>
> - continue;
> + goto put_folio;
> }
>
> - if (!folio_try_get(folio))
> - continue;
> -
> if (unlikely(page_folio(page) != folio))
> goto put_folio;
Will it be necessary to move this check above folio_test_hwpoison trunk too?
Thanks.
.
