4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Kappner <agk@xxxxxxxxxxx> commit d0a0852b9f81cf5f793bf2eae7336ed40a1a1815 upstream. Upon module load, mmc_block allocates a bus with bus_registeri() in mmc_blk_init(). This reference never gets freed during module unload, which leads to subsequent re-insertions of the module fails and a WARN() splat is triggered. Fix the bug by dropping the reference for the bus in mmc_blk_exit(). Signed-off-by: Alexander Kappner <agk@xxxxxxxxxxx> Fixes: 97548575bef3 ("mmc: block: Convert RPMB to a character device") Cc: <stable@xxxxxxxxxxxxxxx> Reviewed-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/mmc/core/block.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -3087,6 +3087,7 @@ static void __exit mmc_blk_exit(void) mmc_unregister_driver(&mmc_driver); unregister_blkdev(MMC_BLOCK_MAJOR, "mmc"); unregister_chrdev_region(mmc_rpmb_devt, MAX_DEVICES); + bus_unregister(&mmc_rpmb_bus_type); } module_init(mmc_blk_init);