From patchwork Thu Jun 5 01:07:38 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu \(Google\)" X-Patchwork-Id: 895036 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6A3C18C00; Thu, 5 Jun 2025 01:07:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749085665; cv=none; b=nTH+qajdniDoO3uT5yB31gBtZUm3cxfYwuq5ugZryp8L2AsSJflEV4oedHBT8nMTm3rqJySu0H0nRNuDp8NsGxVofJya+W8TLlnD1fF0HC0fTVnkfzuCdzkyUhOovBvyMQzfppLl5j2fGF/9xYrNCs4vDqi/kLb/A5YB1fmc4Os= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749085665; c=relaxed/simple; bh=+aLpCNC8OzEHRmMRK/QFfVqV5g0o8xykjr6Q8++9rQk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=TdAx1mKBwTSDfkg0YxnM/EGU9XZMjgh3uyn8mTlimQ9tEWXWZGnvWT9aewZAQwdespUnVQu8ywoBqxR8sEvDyWa+ULqY1BZnMhN8gxo3e6dQwYiFWfKwnpSomB3vyUo/HWXHGF9cuhqyef7OQxQ+EsZb/a+wt2OxOQ9AUo0DNKI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=t2IidH41; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="t2IidH41" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9B2CC4CEE4; Thu, 5 Jun 2025 01:07:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749085662; bh=+aLpCNC8OzEHRmMRK/QFfVqV5g0o8xykjr6Q8++9rQk=; h=From:To:Cc:Subject:Date:From; b=t2IidH412MLiXpk9UtsT7bpSel0KM7VtkNCyhlNNKm1mRAFM9RI/5beDesqRExMIP 04M/3zlAjX5s9/k6qC9+zC8BUFIaSban2+JV84UyIrg3hw4z695JLAk2hrVvMydt79 f3OEx5LZ/pt2kd0IfYtHmA7R3mGG4diwciMqWBm8eMD1gySPvZeOQTdZD25zym8tN9 4hOb2Rz4RQqf9U5OiWSNMaryjGqrzkaTx1FL+M+qnhJQR8d5J9Cg5tAEYuHui+lI/i WmmVK/Ef48KwqurGyeuC0QMCR1oFvH2ve/tjdVa3zd6mTusxD+2/oqhLL56aIfVpBD pzid/Xoppprnw== From: "Masami Hiramatsu (Google)" To: Chaotian Jing , Ulf Hansson , Matthias Brugger , AngeloGioacchino Del Regno Cc: mhiramat@kernel.org, Sergey Senozhatsky , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: [PATCH] mtk-sd: Fix a pagefault in dma_unmap_sg() for not prepared data Date: Thu, 5 Jun 2025 10:07:38 +0900 Message-ID: <174908565814.4056588.769599127120955383.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.49.0.1266.g31b7d2e469-goog User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-mmc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Masami Hiramatsu (Google) mtk-msdc driver causes a kernel crash after swiotlb buffer is full. --- mtk-msdc 11240000.mmc: swiotlb buffer is full (sz: 16384 bytes), total 32768 (slots), used 32732 (slots) mtk-msdc 11240000.mmc: msdc_track_cmd_data: cmd=18 arg=0397A6F8; host->error=0x00000004 Unable to handle kernel paging request at virtual address ffffffffc0001fc0 --- When swiotlb buffer is full, the dma_map_sg() returns 0 to msdc_prepare_data(), but it does not check it and sets the MSDC_PREPARE_FLAG. swiotlb_tbl_map_single() /* prints "swiotlb buffer is full" */ <-swiotlb_map() <-dma_direct_map_page() <-dma_direct_map_sg() <-__dma_map_sg_attrs() <-dma_map_sg_attrs() <-dma_map_sg() /* returns 0 (pages mapped) */ <-msdc_prepare_data() Then, the msdc_unprepare_data() checks MSDC_PREPARE_FLAG and calls dma_unmap_sg() with unmapped pages. It causes a page fault. To fix this problem, Do not set MSDC_PREPARE_FLAG if dma_map_sg() fails because this is not prepared. Fixes: 208489032bdd ("mmc: mediatek: Add Mediatek MMC driver") Signed-off-by: Masami Hiramatsu (Google) --- drivers/mmc/host/mtk-sd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c index 345ea91629e0..3594010bc229 100644 --- a/drivers/mmc/host/mtk-sd.c +++ b/drivers/mmc/host/mtk-sd.c @@ -827,9 +827,10 @@ static inline void msdc_dma_setup(struct msdc_host *host, struct msdc_dma *dma, static void msdc_prepare_data(struct msdc_host *host, struct mmc_data *data) { if (!(data->host_cookie & MSDC_PREPARE_FLAG)) { - data->host_cookie |= MSDC_PREPARE_FLAG; data->sg_count = dma_map_sg(host->dev, data->sg, data->sg_len, mmc_get_dma_dir(data)); + if (data->sg_count) + data->host_cookie |= MSDC_PREPARE_FLAG; } }