The patch titled Subject: mm/memory-failure: teach kill_accessing_process to accept hugetlb tail page pfn has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-memory-failure-teach-kill_accessing_process-to-accept-hugetlb-tail-page-pfn.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Jane Chu jane.chu@oracle.com Subject: mm/memory-failure: teach kill_accessing_process to accept hugetlb tail page pfn Date: Mon, 22 Dec 2025 18:21:12 -0700

When a hugetlb folio is being poisoned again, try_memory_failure_hugetlb() passed head pfn to kill_accessing_process(), that is not right. The precise pfn of the poisoned page should be used in order to determine the precise vaddr as the SIGBUS payload.

This issue has already been taken care of in the normal path, that is, hwpoison_user_mappings(), see [1][2]. Furthermore, for [3] to work correctly in the hugetlb repoisoning case, it's essential to inform VM the precise poisoned page, not the head page.

Link: https://lkml.kernel.org/r/20251223012113.370674-2-jane.chu@oracle.com Link: https://lkml.kernel.org/r/20231218135837.3310403-1-willy@infradead.org [1] Link: https://lkml.kernel.org/r/20250224211445.2663312-1-jane.chu@oracle.com [2] Link: https://lore.kernel.org/lkml/20251116013223.1557158-1-jiaqiyan@google.com/ [3] Signed-off-by: Jane Chu jane.chu@oracle.com Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com Cc: "David Hildenbrand (Red Hat)" david@kernel.org Cc: David Rientjes rientjes@google.com Cc: Jiaqi Yan jiaqiyan@google.com Cc: Lorenzo Stoakes lorenzo.stoakes@oracle.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Miaohe Lin linmiaohe@huawei.com Cc: Michal Hocko mhocko@suse.com Cc: Mike Rapoport rppt@kernel.org Cc: Muchun Song muchun.song@linux.dev Cc: Oscar Salvador osalvador@suse.de Cc: Suren Baghdasaryan surenb@google.com Cc: William Roche william.roche@oracle.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory-failure.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-teach-kill_accessing_process-to-accept-hugetlb-tail-page-pfn +++ a/mm/memory-failure.c @@ -692,6 +692,8 @@ static int check_hwpoisoned_entry(pte_t unsigned long poisoned_pfn, struct to_kill *tk) { unsigned long pfn = 0; + unsigned long hwpoison_vaddr; + unsigned long mask;

if (pte_present(pte)) { pfn = pte_pfn(pte); @@ -702,10 +704,12 @@ static int check_hwpoisoned_entry(pte_t pfn = softleaf_to_pfn(entry); }

- if (!pfn || pfn != poisoned_pfn) + mask = ~((1UL << (shift - PAGE_SHIFT)) - 1); + if (!pfn || ((pfn & mask) != (poisoned_pfn & mask))) return 0;

- set_to_kill(tk, addr, shift); + hwpoison_vaddr = addr + ((poisoned_pfn - pfn) << PAGE_SHIFT); + set_to_kill(tk, hwpoison_vaddr, shift); return 1; }

@@ -2038,10 +2042,8 @@ retry: return 0; case MF_HUGETLB_ALREADY_POISONED: case MF_HUGETLB_ACC_EXISTING_POISON: - if (flags & MF_ACTION_REQUIRED) { - folio = page_folio(p); - res = kill_accessing_process(current, folio_pfn(folio), flags); - } + if (flags & MF_ACTION_REQUIRED) + res = kill_accessing_process(current, pfn, flags); if (res == MF_HUGETLB_ALREADY_POISONED) action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED); else _

Patches currently in -mm which might be from jane.chu@oracle.com are

mm-memory-failure-fix-missing-mf_stats-count-in-hugetlb-poison.patch mm-memory-failure-teach-kill_accessing_process-to-accept-hugetlb-tail-page-pfn.patch