From: David Hildenbrand Date: Sat, 19 Oct 2019 03:20:05 +0000 (-0700) Subject: hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic() X-Git-Tag: v4.19.81~26 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=91eec7692b94cc249af34c7de6d153a372f001b1;p=platform%2Fkernel%2Flinux-rpi.git hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic() 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 Reported-by: Michal Hocko Acked-by: Michal Hocko Reviewed-by: Mike Kravetz Cc: Anshuman Khandual Cc: [4.13+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 57053af..6f4ce95 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1073,11 +1073,10 @@ static bool pfn_range_valid_gigantic(struct zone *z, 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;