• Ralph Campbell's avatar
    mm/hmm: fix bad subpage pointer in try_to_unmap_one · b65f418c
    Ralph Campbell authored
    commit 1de13ee5 upstream.
    
    When migrating an anonymous private page to a ZONE_DEVICE private page,
    the source page->mapping and page->index fields are copied to the
    destination ZONE_DEVICE struct page and the page_mapcount() is
    increased.  This is so rmap_walk() can be used to unmap and migrate the
    page back to system memory.
    
    However, try_to_unmap_one() computes the subpage pointer from a swap pte
    which computes an invalid page pointer and a kernel panic results such
    as:
    
      BUG: unable to handle page fault for address: ffffea1fffffffc8
    
    Currently, only single pages can be migrated to device private memory so
    no subpage computation is needed and it can be set to "page".
    
    [rcampbell@nvidia.com: add comment]
      Link: http://lkml.kernel.org/r/20190724232700.23327-4-rcampbell@nvidia.com
    Link: http://lkml.kernel.org/r/20190719192955.30462-4-rcampbell@nvidia.com
    Fixes: a5430dda ("mm/migrate: support un-addressable ZONE_DEVICE page in migration")
    Signed-off-by: default avatarRalph Campbell <rcampbell@nvidia.com>
    Cc: "Jérôme Glisse" <jglisse@redhat.com>
    Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
    Cc: Mike Kravetz <mike.kravetz@oracle.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Jason Gunthorpe <jgg@mellanox.com>
    Cc: John Hubbard <jhubbard@nvidia.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Ira Weiny <ira.weiny@intel.com>
    Cc: Jan Kara <jack@suse.cz>
    Cc: Lai Jiangshan <jiangshanlai@gmail.com>
    Cc: Logan Gunthorpe <logang@deltatee.com>
    Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Cc: Matthew Wilcox <willy@infradead.org>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: Randy Dunlap <rdunlap@infradead.org>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    b65f418c
rmap.c 54.1 KB