mm: fix initialization of struct page for holes in memory layout
There could be struct pages that are not backed by actual physical memory. This can happen when the actual memory bank is not a multiple of SECTION_SIZE or when an architecture does not register memory holes reserved by the firmware as memblock.memory. Such pages are currently initialized using init_unavailable_mem() function that iterates through PFNs in holes in memblock.memory and if there is a struct page corresponding to a PFN, the fields if this page are set to default values and the page is marked as Reserved. init_unavailable_mem() does not take into account zone and node the page belongs to and sets both zone and node links in struct page to zero. On a system that has firmware reserved holes in a zone above ZONE_DMA, for instance in a configuration below: # grep -A1 E820 /proc/iomem 7a17b000-7a216fff : Unknown E820 type 7a217000-7bffffff : System RAM unset zone link in struct page will trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link in struct page) in the same pageblock. Update init_unavailable_mem() to use zone constraints defined by an architecture to properly setup the zone link and use node ID of the adjacent range in memblock.memory to set the node link. Link: https://lkml.kernel.org/r/20210111194017.22696-3-rppt@kernel.org Fixes: 73a6e474 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") Signed-off-by:Mike Rapoport <rppt@linux.ibm.com> Reported-by:
Andrea Arcangeli <aarcange@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: David Hildenbrand <david@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Qian Cai <cai@lca.pw> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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