From: Dan Williams <dan.j.williams@xxxxxxxxx> Subject: mm: fail get_vaddr_frames() for filesystem-dax mappings Until there is a solution to the dma-to-dax vs truncate problem it is not safe to allow V4L2, Exynos, and other frame vector users to create long standing / irrevocable memory registrations against filesytem-dax vmas. [dan.j.williams@xxxxxxxxx: add comment for vma_is_fsdax() check in get_vaddr_frames(), per Jan] Link: http://lkml.kernel.org/r/151197874035.26211.4061781453123083667.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/151068939985.7446.15684639617389154187.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Cc: Inki Dae <inki.dae@xxxxxxxxxxx> Cc: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx> Cc: Joonyoung Shim <jy0922.shim@xxxxxxxxxxx> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Doug Ledford <dledford@xxxxxxxxxx> Cc: Hal Rosenstock <hal.rosenstock@xxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> Cc: Sean Hefty <sean.hefty@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/frame_vector.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff -puN mm/frame_vector.c~mm-fail-get_vaddr_frames-for-filesystem-dax-mappings mm/frame_vector.c --- a/mm/frame_vector.c~mm-fail-get_vaddr_frames-for-filesystem-dax-mappings +++ a/mm/frame_vector.c @@ -53,6 +53,18 @@ int get_vaddr_frames(unsigned long start ret = -EFAULT; goto out; } + + /* + * While get_vaddr_frames() could be used for transient (kernel + * controlled lifetime) pinning of memory pages all current + * users establish long term (userspace controlled lifetime) + * page pinning. Treat get_vaddr_frames() like + * get_user_pages_longterm() and disallow it for filesystem-dax + * mappings. + */ + if (vma_is_fsdax(vma)) + return -EOPNOTSUPP; + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { vec->got_ref = true; vec->is_pfns = false; _