| From f231fe4235e22e18d847e05cbe705deaca56580a Mon Sep 17 00:00:00 2001 |
| From: David Hildenbrand <david@redhat.com> |
| Date: Fri, 18 Oct 2019 20:20:05 -0700 |
| Subject: hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic() |
| |
| From: David Hildenbrand <david@redhat.com> |
| |
| commit f231fe4235e22e18d847e05cbe705deaca56580a upstream. |
| |
| Uninitialized memmaps contain garbage and in the worst case trigger |
| kernel BUGs, especially with CONFIG_PAGE_POISONING. They should not get |
| touched. |
| |
| Let's make sure that we only consider online memory (managed by the |
| buddy) that has initialized memmaps. ZONE_DEVICE is not applicable. |
| |
| page_zone() will call page_to_nid(), which will trigger |
| VM_BUG_ON_PGFLAGS(PagePoisoned(page), page) with CONFIG_PAGE_POISONING |
| and CONFIG_DEBUG_VM_PGFLAGS when called on uninitialized memmaps. This |
| can be the case when an offline memory block (e.g., never onlined) is |
| spanned by a zone. |
| |
| Note: As explained by Michal in [1], alloc_contig_range() will verify |
| the range. So it boils down to the wrong access in this function. |
| |
| [1] http://lkml.kernel.org/r/20180423000943.GO17484@dhcp22.suse.cz |
| |
| Link: http://lkml.kernel.org/r/20191015120717.4858-1-david@redhat.com |
| Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319] |
| Signed-off-by: David Hildenbrand <david@redhat.com> |
| Reported-by: Michal Hocko <mhocko@kernel.org> |
| Acked-by: Michal Hocko <mhocko@suse.com> |
| Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> |
| Cc: Anshuman Khandual <anshuman.khandual@arm.com> |
| Cc: <stable@vger.kernel.org> [4.13+] |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/hugetlb.c | 5 ++--- |
| 1 file changed, 2 insertions(+), 3 deletions(-) |
| |
| --- a/mm/hugetlb.c |
| +++ b/mm/hugetlb.c |
| @@ -1081,11 +1081,10 @@ static bool pfn_range_valid_gigantic(str |
| struct page *page; |
| |
| for (i = start_pfn; i < end_pfn; i++) { |
| - if (!pfn_valid(i)) |
| + page = pfn_to_online_page(i); |
| + if (!page) |
| return false; |
| |
| - page = pfn_to_page(i); |
| - |
| if (page_zone(page) != z) |
| return false; |
| |