The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b503087445ce7e45fabdee87ca9e460d5b5b5168 Mon Sep 17 00:00:00 2001

From: Peter Collingbourne pcc@google.com Date: Thu, 14 Jan 2021 12:14:05 -0800 Subject: [PATCH] mmc: core: don't initialize block size from ext_csd if not present

If extended CSD was not available, the eMMC driver would incorrectly set the block size to 0, as the data_sector_size field of ext_csd was never initialized. This issue was exposed by commit 817046ecddbc ("block: Align max_hw_sectors to logical blocksize") which caused max_sectors and max_hw_sectors to be set to 0 after setting the block size to 0, resulting in a kernel panic in bio_split when attempting to read from the device. Fix it by only reading the block size from ext_csd if it is available.

Fixes: a5075eb94837 ("mmc: block: Allow disabling 512B sector size emulation") Signed-off-by: Peter Collingbourne pcc@google.com Reviewed-by: Damien Le Moal damien.lemoal@wdc.com Link: https://linux-review.googlesource.com/id/If244d178da4d86b52034459438fec295b0... Acked-by: Adrian Hunter adrian.hunter@intel.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210114201405.2934886-1-pcc@google.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c index de7cb0369c30..002426e3cf76 100644 --- a/drivers/mmc/core/queue.c +++ b/drivers/mmc/core/queue.c @@ -384,8 +384,10 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card) "merging was advertised but not possible"); blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));

- if (mmc_card_mmc(card)) + if (mmc_card_mmc(card) && card->ext_csd.data_sector_size) { block_size = card->ext_csd.data_sector_size; + WARN_ON(block_size != 512 && block_size != 4096); + }

blk_queue_logical_block_size(mq->queue, block_size); /*