Messages in this thread | | | Subject | Re: [PATCH v1] hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic() | From | Mike Kravetz <> | Date | Tue, 15 Oct 2019 11:34:11 -0700 |
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On 10/15/19 5:07 AM, David Hildenbrand wrote: > 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 > > Reported-by: Michal Hocko <mhocko@kernel.org> > Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visible after d0dc12e86b319 > Cc: stable@vger.kernel.org # v4.13+ > Cc: Anshuman Khandual <anshuman.khandual@arm.com> > Cc: Mike Kravetz <mike.kravetz@oracle.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Michal Hocko <mhocko@kernel.org> > Signed-off-by: David Hildenbrand <david@redhat.com>
Thanks David,
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
-- Mike Kravetz
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