4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dan Williams <[email protected]> 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. [[email protected]: 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 <[email protected]> Reviewed-by: Jan Kara <[email protected]> Cc: Inki Dae <[email protected]> Cc: Seung-Woo Kim <[email protected]> Cc: Joonyoung Shim <[email protected]> Cc: Kyungmin Park <[email protected]> Cc: Mauro Carvalho Chehab <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Doug Ledford <[email protected]> Cc: Hal Rosenstock <[email protected]> Cc: Jason Gunthorpe <[email protected]> Cc: Jeff Moyer <[email protected]> Cc: Ross Zwisler <[email protected]> Cc: Sean Hefty <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/frame_vector.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/mm/frame_vector.c +++ b/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;
