Re: [PATCH v5 1/4] mm/memory-failure: report MF_MSG_KERNEL for reserved pages

[Lance Yang]

On Fri, Apr 24, 2026 at 05:23:59AM -0700, Breno Leitao wrote:
>When get_hwpoison_page() returns a negative value, distinguish
>reserved pages from other failure cases by reporting MF_MSG_KERNEL
>instead of MF_MSG_GET_HWPOISON. Reserved pages belong to the kernel
>and should be classified accordingly for proper handling.
>
>Acked-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
>---
> mm/memory-failure.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
>diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>index ee42d43613097..7b67e43dafbd1 100644
>--- a/mm/memory-failure.c
>+++ b/mm/memory-failure.c
>@@ -2432,7 +2432,16 @@ int memory_failure(unsigned long pfn, int flags)
> 		}
> 		goto unlock_mutex;
> 	} else if (res < 0) {
>-		res = action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED);
>+		/*
>+		 * PageReserved is stable here: reserved pages have
>+		 * PG_reserved set at boot or by drivers and are never
>+		 * freed through the page allocator.
>+		 */

Not necessarily. PG_reserved is not a permanent lifetime property for
every page that has carried it.

page-flags.h says early reserved pages may later have PG_reserved
cleared and then be given to the page allocator :)

At least some drivers also clear PG_reserved when releasing pages they
marked reserved.

Would it be clearer to say that pages with PG_reserved set are not
currently managed by the page allocator, rather than saying reserved
pages are never freed through the page allocator?

Otherwise, LGTM.

Reviewed-by: Lance Yang <lance.yang@xxxxxxxxx>