]> www.infradead.org Git - users/jedix/linux-maple.git/commit
mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage
authorNaoya Horiguchi <naoya.horiguchi@nec.com>
Thu, 14 Jul 2022 04:24:19 +0000 (13:24 +0900)
committerLiam R. Howlett <Liam.Howlett@oracle.com>
Wed, 3 Aug 2022 18:17:12 +0000 (14:17 -0400)
commit67404fd89cfad51b2bac4ae6641d960e7b915690
treea89a121a00991703311ce4cee3710e467aa54844
parent7582b19d3ff018f051c76e4fbf96c808d7fb5336
mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage

Currently if memory_failure() (modified to remove blocking code with
subsequent patch) is called on a page in some 1GB hugepage, memory error
handling fails and the raw error page gets into leaked state.  The impact
is small in production systems (just leaked single 4kB page), but this
limits the testability because unpoison doesn't work for it.  We can no
longer create 1GB hugepage on the 1GB physical address range with such
leaked pages, that's not useful when testing on small systems.

When a hwpoison page in a 1GB hugepage is handled, it's caught by the
PageHWPoison check in free_pages_prepare() because the 1GB hugepage is
broken down into raw error pages before coming to this point:

        if (unlikely(PageHWPoison(page)) && !order) {
                ...
                return false;
        }

Then, the page is not sent to buddy and the page refcount is left 0.

Originally this check is supposed to work when the error page is freed
from page_handle_poison() (that is called from soft-offline), but now we
are opening another path to call it, so the callers of
__page_handle_poison() need to handle the case by considering the return
value 0 as success.  Then page refcount for hwpoison is properly
incremented so unpoison works.

Link: https://lkml.kernel.org/r/20220714042420.1847125-8-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/memory-failure.c