+ mm-memory_hotplug-fix-hwpoisoned-large-folio-handling-in-do_migrate_range.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-memory_hotplug-fix-hwpoisoned-large-folio-handling-in-do_migrate_range.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory_hotplug-fix-hwpoisoned-large-folio-handling-in-do_migrate_range.patch

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: Jinjiang Tu <tujinjiang@huawei.com>
Subject: mm/memory_hotplug: fix hwpoisoned large folio handling in do_migrate_range()
Date: Fri, 27 Jun 2025 20:57:47 +0800

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>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Raghav <kernel@pankajraghav.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory_hotplug.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/mm/memory_hotplug.c~mm-memory_hotplug-fix-hwpoisoned-large-folio-handling-in-do_migrate_range
+++ a/mm/memory_hotplug.c
@@ -1815,8 +1815,14 @@ static void do_migrate_range(unsigned lo
 			pfn = folio_pfn(folio) + folio_nr_pages(folio) - 1;
 
 		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);
_

Patches currently in -mm which might be from tujinjiang@huawei.com are

mm-memory_hotplug-fix-hwpoisoned-large-folio-handling-in-do_migrate_range.patch