On Sun, 29 Nov 2020 at 19:20, Martin DEVERA <devik@xxxxxxxxxx> wrote: > > Hello, > > on STM32MP1 with almost vanilla 5.7.7 in single CPU mode. Pair of > modprobe armmmci ; rmmod armmmci > > causes rmmod and kworker to hang. I should note that no MMC is detected > on the board (SDIO device on MMC bus is not responding). > On another board (where SDIO is responding) rmmod works. > > It seems as another manifestation of https://lkml.org/lkml/2019/8/27/945 > > Thanks. > > INFO: task kworker/0:1:12 blocked for more than 368 seconds. > Not tainted 5.7.7kdb-00003-g10397828596c-dirty #224 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kworker/0:1 D 0 12 2 0x00000000 > Workqueue: events_freezable mmc_rescan > (__schedule) from (schedule+0x5b/0x90) > (schedule) from (schedule_timeout+0x1b/0xa0) > (schedule_timeout) from (__wait_for_common+0x7d/0xdc) > (__wait_for_common) from (mmc_wait_for_req_done+0x1b/0x8c) > (mmc_wait_for_req_done) from (mmc_wait_for_cmd+0x4d/0x68) > (mmc_wait_for_cmd) from (mmc_io_rw_direct_host+0x87/0xc8) > (mmc_io_rw_direct_host) from (sdio_reset+0x3b/0x58) > (sdio_reset) from (mmc_rescan+0x15d/0x1d4) > (mmc_rescan) from (process_one_work+0xdd/0x168) > (process_one_work) from (worker_thread+0x17d/0x1ec) > (worker_thread) from (kthread+0x9b/0xa4) > (kthread) from (ret_from_fork+0x11/0x28) It looks like the worker thread, which runs mmc_rescan() to try to detect the SDIO card is hanging. Exactly why, I don't know. Could be a misconfigured clock, pinctrl or a power domain being suddenly gated... > > INFO: task rmmod:308 blocked for more than 368 seconds. > Not tainted 5.7.7kdb-00003-g10397828596c-dirty #224 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > rmmod D 0 308 222 0x00000000 > (__schedule) from (schedule+0x5b/0x90) > (schedule) from (schedule_timeout+0x1b/0xa0) > (schedule_timeout) from (__wait_for_common+0x7d/0xdc) > (__wait_for_common) from (__flush_work+0xb3/0x110) > (__flush_work) from (__cancel_work_timer+0x97/0xf0) > (__cancel_work_timer) from (mmc_stop_host+0x29/0x88) > (mmc_stop_host) from (mmc_remove_host+0x9/0x22) > (mmc_remove_host) from (mmci_remove+0x19/0x92 [armmmci]) > (mmci_remove [armmmci]) from (amba_remove+0x13/0x42) > (amba_remove) from (device_release_driver_internal+0x89/0xe4) > (device_release_driver_internal) from (driver_detach+0x57/0x60) > (driver_detach) from (bus_remove_driver+0x53/0x84) > (bus_remove_driver) from (mmci_driver_exit+0x9/0x11dc [armmmci]) > (mmci_driver_exit [armmmci]) from (sys_delete_module+0x115/0x154) > (sys_delete_module) from (ret_fast_syscall+0x1/0x5a) > When unbinding the mmc host, mmc_stop_host() needs to make sure that mmc_rescan() becomes disabled. This is to prevent a card from being detected/removed at same time as when the host is being removed. In any case, when we call... cancel_delayed_work_sync(&host->detect); ...it seems like we end up waiting for the currently running mmc_rescan() work to be completed. Kind regards Uffe
