[PATCH 6.12] mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range()

[PATCH 6.12] mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range()

[Alexandra Diupina]

From: Jinjiang Tu <tujinjiang@huawei.com>

commit 397f6d14f9c370e4910e6885294c340f39dedbf5 upstream.

In do_migrate_range(), the hwpoisoned folio may be large folio, which
can't be handled by unmap_poisoned_folio().

I can reproduce this issue in qemu after adding delay in memory_failure()

BUG: kernel NULL pointer dereference, address: 0000000000000000
Workqueue: kacpi_hotplug acpi_hotplug_work_fn
RIP: 0010:try_to_unmap_one+0x16a/0xfc0
  <TASK>
  rmap_walk_anon+0xda/0x1f0
  try_to_unmap+0x78/0x80
  ? __pfx_try_to_unmap_one+0x10/0x10
  ? __pfx_folio_not_mapped+0x10/0x10
  ? __pfx_folio_lock_anon_vma_read+0x10/0x10
  unmap_poisoned_folio+0x60/0x140
  do_migrate_range+0x4d1/0x600
  ? slab_memory_callback+0x6a/0x190
  ? notifier_call_chain+0x56/0xb0
  offline_pages+0x3e6/0x460
  memory_subsys_offline+0x130/0x1f0
  device_offline+0xba/0x110
  acpi_bus_offline+0xb7/0x130
  acpi_scan_hot_remove+0x77/0x290
  acpi_device_hotplug+0x1e0/0x240
  acpi_hotplug_work_fn+0x1a/0x30
  process_one_work+0x186/0x340

Besides, do_migrate_range() may be called between memory_failure set
hwpoison flag and isolate the folio from lru, so remove WARN_ON(). In other
places, unmap_poisoned_folio() is called when the folio is isolated, obey
it in do_migrate_range() too.

[david@redhat.com: don't abort offlining, fixed typo, add comment]
Link: https://lkml.kernel.org/r/3c214dff-9649-4015-840f-10de0e03ebe4@redhat.com
Fixes: b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Raghav <kernel@pankajraghav.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
---
 mm/memory_hotplug.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0a42e9a8caba..16d788547b9b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1802,8 +1802,14 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 			goto put_folio;
 
 		if (folio_contain_hwpoisoned_page(folio)) {
-			if (WARN_ON(folio_test_lru(folio)))
-				folio_isolate_lru(folio);
+			/*
+			 * unmap_poisoned_folio() cannot handle large folios
+			 * in all cases yet.
+			 */
+			if (folio_test_large(folio) && !folio_test_hugetlb(folio))
+				goto put_folio;
+			if (folio_test_lru(folio) && !folio_isolate_lru(folio))
+				goto put_folio;
 			if (folio_mapped(folio)) {
 				folio_lock(folio);
 				unmap_poisoned_folio(folio, pfn, false);
-- 
2.30.2

Re: [PATCH 6.12] mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range()

[Sasha Levin]

On Thu, Apr 30, 2026 at 02:37:31PM +0300, Alexandra Diupina wrote:
> From: Jinjiang Tu <tujinjiang@huawei.com>
>
> commit 397f6d14f9c370e4910e6885294c340f39dedbf5 upstream.
>
> In do_migrate_range(), the hwpoisoned folio may be large folio, which
> can't be handled by unmap_poisoned_folio().

Thanks, queued for 6.12.y.

--
Thanks,
Sasha