commit b7f0554a56f21fb3e636a627450a9add030889be upstream. 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.willi...@intel.com: add comment for vma_is_fsdax() check in get_vaddr_frames(), per Jan] Link: http://lkml.kernel.org/r/151197874035.26211.4061781453123083667.st...@dwillia2-desk3.amr.corp.intel.com Link: http://lkml.kernel.org/r/151068939985.7446.15684639617389154187.st...@dwillia2-desk3.amr.corp.intel.com Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") Signed-off-by: Dan Williams <dan.j.willi...@intel.com> Reviewed-by: Jan Kara <j...@suse.cz> Cc: Inki Dae <inki....@samsung.com> Cc: Seung-Woo Kim <sw0312....@samsung.com> Cc: Joonyoung Shim <jy0922.s...@samsung.com> Cc: Kyungmin Park <kyungmin.p...@samsung.com> Cc: Mauro Carvalho Chehab <mche...@kernel.org> Cc: Mel Gorman <mgor...@suse.de> Cc: Vlastimil Babka <vba...@suse.cz> Cc: Christoph Hellwig <h...@lst.de> Cc: Doug Ledford <dledf...@redhat.com> Cc: Hal Rosenstock <hal.rosenst...@gmail.com> Cc: Jason Gunthorpe <j...@mellanox.com> Cc: Jeff Moyer <jmo...@redhat.com> Cc: Ross Zwisler <ross.zwis...@linux.intel.com> Cc: Sean Hefty <sean.he...@intel.com> Cc: <sta...@vger.kernel.org> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> --- mm/frame_vector.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/frame_vector.c b/mm/frame_vector.c index db77dcb38afd..375a103d7a56 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -52,6 +52,18 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, 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;
