The patch titled
Subject: hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic()
has been added to the -mm tree. Its filename is
hugetlbfs-dont-access-uninitialized-memmaps-in-pfn_range_valid_gigantic.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/hugetlbfs-dont-access-uninitialized-memmaps-in-pfn_range_valid_gigantic.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/hugetlbfs-dont-access-uninitialized-memmaps-in-pfn_range_valid_gigantic.patch
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic()
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@xxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20191015120717.4858-1-david@xxxxxxxxxx
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319]
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reported-by: Michal Hocko <mhocko@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.13+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/mm/hugetlb.c~hugetlbfs-dont-access-uninitialized-memmaps-in-pfn_range_valid_gigantic
+++ a/mm/hugetlb.c
@@ -1084,11 +1084,10 @@ 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;
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
drivers-base-memoryc-dont-access-uninitialized-memmaps-in-soft_offline_page_store.patch
mm-dont-access-uninitialized-memmaps-in-fs-proc-pagec.patch
mm-memory-failurec-dont-access-uninitialized-memmaps-in-memory_failure.patch
mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_pgdat_span.patch
hugetlbfs-dont-access-uninitialized-memmaps-in-pfn_range_valid_gigantic.patch
mm-memory_hotplug-export-generic_online_page.patch
hv_balloon-use-generic_online_page.patch
mm-memory_hotplug-remove-__online_page_free-and-__online_page_increment_counters.patch
mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_zone_span.patch
mm-memory_hotplug-shrink-zones-when-offlining-memory.patch
mm-memory_hotplug-poison-memmap-in-remove_pfn_range_from_zone.patch
mm-memory_hotplug-we-always-have-a-zone-in-find_smallestbiggest_section_pfn.patch
mm-memory_hotplug-dont-check-for-all-holes-in-shrink_zone_span.patch
mm-memory_hotplug-drop-local-variables-in-shrink_zone_span.patch
mm-memory_hotplug-cleanup-__remove_pages.patch
