From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227dxpUpphnTzQFb7OpaRvpVL3WjVqTUIYkwL+fLf4gdkMVoMM5NHqjjozQ0SqJb8Rf9hiPF ARC-Seal: i=1; a=rsa-sha256; t=1519424100; cv=none; d=google.com; s=arc-20160816; b=CMD+3vQdpv7oecyADNuHBeIIu7vvz6Ucikedz45df2hwnFqlzQqo1VwDdSzFvt70io kkEbfAPEGH07dH9N+a5E5EULzHkK0mUoygbNObAYKq6qPlQ5WLue/m25Vh4ZIDY+DGMJ UcVfiee7O6QBStq0xDTB5GjE5ccef3HNmLxF1P+Ee9qOLkKBdW9/UZjoFnSaLufGmmLN OOrEtN1NPp1Cvkz3Ujpnvj76eEoqnLiM8EI33bGjQayRvpkbXDzuoEnvRqw+1OseAe8O rVp7KgcNHAKDezOyFtB1s68OBqE3g0HXlT1T4dhzJpWSZKUi2T4sDokkCUdwKmg+5Hsd mzXQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:user-agent:references :in-reply-to:message-id:date:cc:to:from:subject :arc-authentication-results; bh=7ecC+RsWIhOHu+HKMG2yvUfLbzBLrS6MLd9U/UCPSLM=; b=jfCMd0L6h7NrmYUU8GNNks9wj+YbDKEQF7WQgfh7RtzYMBT0cUfpeHyznekA8DFJLF btBhxjlKJCdzthFV2BfRHbgLztZeQOKtW5FkggG1vADOhlSBzBncGGNvwvJGwuPb1BLh 9ePPeKV2bXJosiwd26XMRSS8c4N+eauD8RWs6K0xzFYtyPEalIv6Sv372G1ov690dOr6 jyNat4WbXUbBeRBSCR88uH+q+TgaTYVClZzXzQRv8jiAeGS4xCC/TJsYvtNFFWpnESqw sP33uZVGT8SDBcvVU176cLLnP2vkq7+4GF8DujJ/Uj6PtVDt9PB3K9S7fA1mWi+pv8QC c6oA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of dan.j.williams@intel.com designates 134.134.136.20 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of dan.j.williams@intel.com designates 134.134.136.20 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,383,1515484800"; d="scan'208";a="22639784" Subject: [4.9-stable PATCH 06/11] v4l2: disable filesystem-dax mapping support From: Dan Williams To: gregkh@linuxfoundation.org Cc: Jan Kara , Joonyoung Shim , linux-kernel@vger.kernel.org, Seung-Woo Kim , Doug Ledford , stable@vger.kernel.org, Christoph Hellwig , Inki Dae , Jeff Moyer , Jason Gunthorpe , Mel Gorman , Andrew Morton , Ross Zwisler , Kyungmin Park , Sean Hefty , Mauro Carvalho Chehab , Linus Torvalds , Hal Rosenstock , Vlastimil Babka Bcc: dan.j.williams@intel.com Date: Fri, 23 Feb 2018 14:05:54 -0800 Message-ID: <151942355435.21775.3892492011172127062.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <151942352167.21775.16852023419062929165.stgit@dwillia2-desk3.amr.corp.intel.com> References: <151942352167.21775.16852023419062929165.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1593231645761720959?= X-GMAIL-MSGID: =?utf-8?q?1593231645761720959?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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 Reported-by: Jan Kara Reviewed-by: Jan Kara Cc: Mauro Carvalho Chehab Cc: Christoph Hellwig Cc: Doug Ledford Cc: Hal Rosenstock Cc: Inki Dae Cc: Jason Gunthorpe Cc: Jeff Moyer Cc: Joonyoung Shim Cc: Kyungmin Park Cc: Mel Gorman Cc: Ross Zwisler Cc: Sean Hefty Cc: Seung-Woo Kim Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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;