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Message-ID: <151942355435.21775.3892492011172127062.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Fri, 23 Feb 2018 14:05:54 -0800
From: Dan Williams <dan.j.williams@...el.com>
To: gregkh@...uxfoundation.org
Cc: Jan Kara <jack@...e.cz>, Joonyoung Shim <jy0922.shim@...sung.com>,
linux-kernel@...r.kernel.org,
Seung-Woo Kim <sw0312.kim@...sung.com>,
Doug Ledford <dledford@...hat.com>, stable@...r.kernel.org,
Christoph Hellwig <hch@....de>,
Inki Dae <inki.dae@...sung.com>,
Jeff Moyer <jmoyer@...hat.com>,
Jason Gunthorpe <jgg@...lanox.com>,
Mel Gorman <mgorman@...e.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Sean Hefty <sean.hefty@...el.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Hal Rosenstock <hal.rosenstock@...il.com>,
Vlastimil Babka <vbabka@...e.cz>
Subject: [4.9-stable PATCH 06/11] v4l2: disable filesystem-dax mapping
support
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@dwillia2-desk3.amr.corp.intel.com
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Reported-by: Jan Kara <jack@...e.cz>
Reviewed-by: Jan Kara <jack@...e.cz>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: Christoph Hellwig <hch@....de>
Cc: Doug Ledford <dledford@...hat.com>
Cc: Hal Rosenstock <hal.rosenstock@...il.com>
Cc: Inki Dae <inki.dae@...sung.com>
Cc: Jason Gunthorpe <jgg@...lanox.com>
Cc: Jeff Moyer <jmoyer@...hat.com>
Cc: Joonyoung Shim <jy0922.shim@...sung.com>
Cc: Kyungmin Park <kyungmin.park@...sung.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc: Sean Hefty <sean.hefty@...el.com>
Cc: Seung-Woo Kim <sw0312.kim@...sung.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
---
drivers/media/v4l2-core/videobuf-dma-sg.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index 1db0af6c7f94..b6189a4958c5 100644
--- 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(struct videobuf_dmabuf *dma,
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;
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