5.4-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu (Google) mhiramat@kernel.org
commit 539d80575b810c7a5987c7ac8915e3bc99c03695 upstream.
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) mhiramat@kernel.org Tested-by: Sergey Senozhatsky senozhatsky@chromium.org Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/174908565814.4056588.769599127120955383.stgit@mhir... Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/mmc/host/mtk-sd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/mmc/host/mtk-sd.c +++ b/drivers/mmc/host/mtk-sd.c @@ -681,9 +681,10 @@ static void msdc_prepare_data(struct msd struct mmc_data *data = mrq->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; } }