This is a note to let you know that I've just added the patch titled
v4l2: disable filesystem-dax mapping support
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: v4l2-disable-filesystem-dax-mapping-support.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Feb 26 20:55:53 CET 2018
From: Dan Williams dan.j.williams@intel.com Date: Fri, 23 Feb 2018 14:05:54 -0800 Subject: v4l2: disable filesystem-dax mapping support To: gregkh@linuxfoundation.org Cc: Jan Kara jack@suse.cz, Joonyoung Shim jy0922.shim@samsung.com, linux-kernel@vger.kernel.org, Seung-Woo Kim sw0312.kim@samsung.com, Doug Ledford dledford@redhat.com, stable@vger.kernel.org, Christoph Hellwig hch@lst.de, Inki Dae inki.dae@samsung.com, Jeff Moyer jmoyer@redhat.com, Jason Gunthorpe jgg@mellanox.com, Mel Gorman mgorman@suse.de, Andrew Morton akpm@linux-foundation.org, Ross Zwisler ross.zwisler@linux.intel.com, Kyungmin Park kyungmin.park@samsung.com, Sean Hefty sean.hefty@intel.com, Mauro Carvalho Chehab mchehab@kernel.org, Linus Torvalds torvalds@linux-foundation.org, Hal Rosenstock hal.rosenstock@gmail.com, Vlastimil Babka vbabka@suse.cz Message-ID: 151942355435.21775.3892492011172127062.stgit@dwillia2-desk3.amr.corp.intel.com
From: Dan Williams dan.j.williams@intel.com
commit b70131de648c2b997d22f4653934438013f407a1 upstream.
V4L2 memory registrations are incompatible with filesystem-dax that needs the ability to revoke dma access to a mapping at will, or otherwise allow the kernel to wait for completion of DMA. The filesystem-dax implementation breaks the traditional solution of truncate of active file backed mappings since there is no page-cache page we can orphan to sustain ongoing DMA.
If v4l2 wants to support long lived DMA mappings it needs to arrange to hold a file lease or use some other mechanism so that the kernel can coordinate revoking DMA access when the filesystem needs to truncate mappings.
Link: http://lkml.kernel.org/r/151068940499.7446.12846708245365671207.stgit@dwilli... Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") Signed-off-by: Dan Williams dan.j.williams@intel.com Reported-by: Jan Kara jack@suse.cz Reviewed-by: Jan Kara jack@suse.cz Cc: Mauro Carvalho Chehab mchehab@kernel.org Cc: Christoph Hellwig hch@lst.de Cc: Doug Ledford dledford@redhat.com Cc: Hal Rosenstock hal.rosenstock@gmail.com Cc: Inki Dae inki.dae@samsung.com Cc: Jason Gunthorpe jgg@mellanox.com Cc: Jeff Moyer jmoyer@redhat.com Cc: Joonyoung Shim jy0922.shim@samsung.com Cc: Kyungmin Park kyungmin.park@samsung.com Cc: Mel Gorman mgorman@suse.de Cc: Ross Zwisler ross.zwisler@linux.intel.com Cc: Sean Hefty sean.hefty@intel.com Cc: Seung-Woo Kim sw0312.kim@samsung.com Cc: Vlastimil Babka vbabka@suse.cz Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/v4l2-core/videobuf-dma-sg.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c +++ b/drivers/media/v4l2-core/videobuf-dma-sg.c @@ -185,12 +185,13 @@ static int videobuf_dma_init_user_locked dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n", data, size, dma->nr_pages);
- err = get_user_pages(data & PAGE_MASK, dma->nr_pages, + err = get_user_pages_longterm(data & PAGE_MASK, dma->nr_pages, flags, dma->pages, NULL);
if (err != dma->nr_pages) { dma->nr_pages = (err >= 0) ? err : 0; - dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages); + dprintk(1, "get_user_pages_longterm: err=%d [%d]\n", err, + dma->nr_pages); return err < 0 ? err : -EINVAL; } return 0;
Patches currently in stable-queue which might be from dan.j.williams@intel.com are
queue-4.9/mm-fix-devm_memremap_pages-collision-handling.patch queue-4.9/ib-core-disable-memory-registration-of-filesystem-dax-vmas.patch queue-4.9/mm-avoid-spurious-bad-pmd-warning-messages.patch queue-4.9/mm-introduce-get_user_pages_longterm.patch queue-4.9/mm-fail-get_vaddr_frames-for-filesystem-dax-mappings.patch queue-4.9/fs-dax.c-fix-inefficiency-in-dax_writeback_mapping_range.patch queue-4.9/device-dax-implement-split-to-catch-invalid-munmap-attempts.patch queue-4.9/v4l2-disable-filesystem-dax-mapping-support.patch queue-4.9/libnvdimm-dax-fix-1gb-aligned-namespaces-vs-physical-misalignment.patch queue-4.9/x86-entry-64-clear-extra-registers-beyond-syscall-arguments-to-reduce-speculation-attack-surface.patch queue-4.9/libnvdimm-fix-integer-overflow-static-analysis-warning.patch