Re: [PATCH v7 1/6] mm/memory-failure: drop dead error_states[] entry for reserved pages

[Miaohe Lin <linmiaohe@huawei.com>]

On 2026/5/13 23:39, Breno Leitao wrote:
> The first entry of error_states[],
> 
> 	{ reserved,	reserved,	MF_MSG_KERNEL,	me_kernel },
> 
> is unreachable.  identify_page_state() has two callers, and neither
> one can dispatch a PG_reserved page to me_kernel():
> 
>   * memory_failure() reaches identify_page_state() only after
>     get_hwpoison_page() returned 1.  get_any_page() reaches that
>     return only via __get_hwpoison_page(), which gates the refcount
>     on HWPoisonHandlable().  HWPoisonHandlable() rejects PG_reserved
>     pages, so they fail with -EBUSY/-EIO long before
>     identify_page_state() runs.
> 
>   * try_memory_failure_hugetlb() reaches identify_page_state() on
>     the MF_HUGETLB_IN_USED branch, but the page is necessarily a
>     hugetlb folio there.  The first table entry that matches a
>     hugetlb folio is { head, head, MF_MSG_HUGE, me_huge_page }, so
>     they dispatch to me_huge_page() before the (now-removed)
>     reserved entry would have matched, regardless of whether
>     PG_reserved happens to be set on the head page.
> 
> me_kernel() never executes and the entry exists only to be matched
> against by code that cannot see it.
> 
> Drop the entry, the me_kernel() helper, and the now-unused
> "reserved" macro.  Leave the MF_MSG_KERNEL enum value in place: it
> remains part of the tracepoint and pr_err() string tables, and
> follow-on work to classify unrecoverable kernel pages can reuse it
> without churning the user-visible enum.
> 
> No functional change.

As the code evolves, this entry is no longer needed. Thanks for cleanup.

> 
> Suggested-by: David Hildenbrand <david@kernel.org>
> Signed-off-by: Breno Leitao <leitao@debian.org>

With David's comments addressed, this patch looks good to me:

Acked-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks.
.