| Message ID | 151068939985.7446.15684639617389154187.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue 14-11-17 11:56:39, Dan Williams wrote: > 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. > > 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: linux-media@vger.kernel.org > Cc: Jan Kara <jack@suse.cz> > Cc: Mel Gorman <mgorman@suse.de> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: <stable@vger.kernel.org> > Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") > Signed-off-by: Dan Williams <dan.j.williams@intel.com> Makes sense. I'd just note that in principle get_vaddr_frames() is no more long-term than get_user_pages(). It is just so that all the users of get_vaddr_frames() currently want a long-term reference. Maybe could you add here also a comment that the vma_is_fsdax() check is there because all users of this function want a long term page reference? With that you can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > mm/frame_vector.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > index 72ebec18629c..d2fdbeaadc8b 100644 > --- a/mm/frame_vector.c > +++ b/mm/frame_vector.c > @@ -52,6 +52,10 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > ret = -EFAULT; > goto out; > } > + > + if (vma_is_fsdax(vma)) > + return -EOPNOTSUPP; > + > if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { > vec->got_ref = true; > vec->is_pfns = false; >
On Mon, Nov 27, 2017 at 8:15 AM, Jan Kara <jack@suse.cz> wrote: > On Tue 14-11-17 11:56:39, Dan Williams wrote: >> 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. >> >> 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: linux-media@vger.kernel.org >> Cc: Jan Kara <jack@suse.cz> >> Cc: Mel Gorman <mgorman@suse.de> >> Cc: Vlastimil Babka <vbabka@suse.cz> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: <stable@vger.kernel.org> >> Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") >> Signed-off-by: Dan Williams <dan.j.williams@intel.com> > > Makes sense. I'd just note that in principle get_vaddr_frames() is no more > long-term than get_user_pages(). It is just so that all the users of > get_vaddr_frames() currently want a long-term reference. Maybe could you > add here also a comment that the vma_is_fsdax() check is there because all > users of this function want a long term page reference? With that you can > add: Ok, will do. > Reviewed-by: Jan Kara <jack@suse.cz> Thanks.
diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 72ebec18629c..d2fdbeaadc8b 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -52,6 +52,10 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, ret = -EFAULT; goto out; } + + if (vma_is_fsdax(vma)) + return -EOPNOTSUPP; + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { vec->got_ref = true; vec->is_pfns = false;
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. 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: linux-media@vger.kernel.org Cc: Jan Kara <jack@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <stable@vger.kernel.org> Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- mm/frame_vector.c | 4 ++++ 1 file changed, 4 insertions(+)