New subject: Patch "mm: fail get_vaddr_frames() for filesystem-dax mappings" has been added to the 4.9-stable tree

23 Feb 2018

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.williams@intel.com: add comment for vma_is_fsdax() check in get_vaddr_frames(), per Jan]
  Link: http://lkml.kernel.org/r/151197874035.26211.4061781453123083667.stgit@dwilli...
Link: http://lkml.kernel.org/r/151068939985.7446.15684639617389154187.stgit@dwilli...
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Dan Williams dan.j.williams@intel.com
Reviewed-by: Jan Kara jack@suse.cz
Cc: Inki Dae inki.dae@samsung.com
Cc: Seung-Woo Kim sw0312.kim@samsung.com
Cc: Joonyoung Shim jy0922.shim@samsung.com
Cc: Kyungmin Park kyungmin.park@samsung.com
Cc: Mauro Carvalho Chehab mchehab@kernel.org
Cc: Mel Gorman mgorman@suse.de
Cc: Vlastimil Babka vbabka@suse.cz
Cc: Christoph Hellwig hch@lst.de
Cc: Doug Ledford dledford@redhat.com
Cc: Hal Rosenstock hal.rosenstock@gmail.com
Cc: Jason Gunthorpe jgg@mellanox.com
Cc: Jeff Moyer jmoyer@redhat.com
Cc: Ross Zwisler ross.zwisler@linux.intel.com
Cc: Sean Hefty sean.hefty@intel.com
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton akpm@linux-foundation.org
Signed-off-by: Linus Torvalds torvalds@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;

    

[4.9-stable PATCH 10/11] mm: fail get_vaddr_frames() for filesystem-dax mappings