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... and later at http://ozlabs.org/~akpm/mmotm/broken-out/hugetlbfs-dont-access-uninitialized...
Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated there every 3-4 working days
------------------------------------------------------ From: David Hildenbrand david@redhat.com 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@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 Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Mike Kravetz mike.kravetz@oracle.com Cc: stable@vger.kernel.org [4.13+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
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@redhat.com 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