mm: memory_hotplug: check hwpoisoned page firstly in do_migrate_range()

Commit b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to
be offlined") don't handle the hugetlb pages, the endless loop still occur
if offline a hwpoison hugetlb page, luckly, after the commit e591ef7d96d6
("mm, hwpoison,hugetlb,memory_hotplug: hotremove memory section with
hwpoisoned hugepage"), the HPageMigratable of hugetlb page will be
cleared, and the hwpoison hugetlb page will be skipped in
scan_movable_pages(), so the endless loop issue is fixed.

However if the HPageMigratable() check passed(without reference and lock),
the hugetlb page may be hwpoisoned, it won't cause issue since the
hwpoisoned page will be handled correctly in the next movable pages scan
loop, and it will be isolated in do_migrate_range() but fails to migrate.
In order to avoid the unnecessary isolation and unify all hwpoisoned page
handling, let's unconditionally check hwpoison firstly, and if it is a
hwpoisoned hugetlb page, try to unmap it as the catch all safety net like
normal page does.

Link: https://lkml.kernel.org/r/20240827114728.3212578-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3f8a109d51293b33bb23259aff582c024c76208a..6bdac4cddd9f7040c9ea1d79a8aa836f6e19123e 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1793,26 +1793,26 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
                 * folio_nr_pages() may read garbage.  This is fine as the outer
                 * loop will revisit the split folio later.
                 */
-               if (folio_test_large(folio)) {
+               if (folio_test_large(folio))
                        pfn = folio_pfn(folio) + folio_nr_pages(folio) - 1;
-                       if (folio_test_hugetlb(folio)) {
-                               isolate_hugetlb(folio, &source);
-                               continue;
-                       }
-               }
 
                /*
                 * HWPoison pages have elevated reference counts so the migration would
                 * fail on them. It also doesn't make any sense to migrate them in the
                 * first place. Still try to unmap such a page in case it is still mapped
-                * (e.g. current hwpoison implementation doesn't unmap KSM pages but keep
-                * the unmap as the catch all safety net).
+                * (keep the unmap as the catch all safety net).
                 */
-               if (PageHWPoison(page)) {
+               if (folio_test_hwpoison(folio) ||
+                   (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) {
                        if (WARN_ON(folio_test_lru(folio)))
                                folio_isolate_lru(folio);
                        if (folio_mapped(folio))
-                               try_to_unmap(folio, TTU_IGNORE_MLOCK);
+                               unmap_poisoned_folio(folio, TTU_IGNORE_MLOCK);
+                       continue;
+               }
+
+               if (folio_test_hugetlb(folio)) {
+                       isolate_hugetlb(folio, &source);
                        continue;
                }