armmmci rmmod causes hung tasks

[Ulf Hansson]

On Mon, 30 Nov 2020 at 18:20, Martin DEVERA <devik at eaxlabs.cz> wrote:
>
> On 11/30/20 4:08 PM, Ulf Hansson wrote:
> > On Sun, 29 Nov 2020 at 19:20, Martin DEVERA <devik at eaxlabs.cz> 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...
>
> I turned some logging on (see below), IIUC pl18x is starting CMD52 with arg
> SDIO_CCCR_ABORT read and it got IRQ later along with response. Then sending
> again SDIO_CCCR_ABORT write but no IRQ comes back.
>
> [  135.810802] mmc0: mmc_rescan_try_freq: trying to init card at 400000 Hz
> [  135.810832] mmc0: starting CMD52 arg 00000c00 flags 00000195
> [  135.810862] mmci-pl18x 48004000.sdmmc: op 34 arg 00000c00 flags 00000195
> [  135.811155] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000040
> [  135.811178] mmc0: req done (CMD52): 0: 00000000 00000000 00000000
> 00000000
> [  135.811202] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000000
> [  135.816487] mmc0: starting CMD52 arg 80000c08 flags 00000195
> [  135.816506] mmci-pl18x 48004000.sdmmc: op 34 arg 80000c08 flags 00000195
> [  172.150614] random: crng init done
> [  172.150642] random: 6 urandom warning(s) missed due to ratelimiting
> [  173.290565] INFO: task kworker/0:0:5 blocked for more than 20 seconds.
>
> Here is the same system, only with different (working) SDIO device on
> the same bus:
>
> [  495.654596] mmc0: mmc_rescan_try_freq: trying to init card at 400000 Hz
> [  495.654628] mmc0: starting CMD52 arg 00000c00 flags 00000195
> [  495.654658] mmci-pl18x 48004000.sdmmc: op 34 arg 00000c00 flags 00000195
> [  495.654996] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000004
> [  495.655017] mmc0: req done (CMD52): -110: 00000000 00000000 00000000
> 00000000
> [  495.655042] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000000
> [  495.660201] mmc0: starting CMD52 arg 80000c08 flags 00000195
> [  495.660222] mmci-pl18x 48004000.sdmmc: op 34 arg 80000c08 flags 00000195
> [  495.660549] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000004
> [  495.660567] mmc0: req done (CMD52): -110: 00000000 00000000 00000000
> 00000000
> [  495.660591] mmci-pl18x 48004000.sdmmc: irq0 (data+cmd) 00000000
>
> Should it be expected, that invalid (probably non-responding) device on
> the SDIO bus
> causes it to be locked up forever ?
> Or is it bug in pl18x driver not handling the error correctly ?

Honestly, it's hard to tell without further debugging. It looks like a
bug in pl18x driver, but perhaps also on the SDIO device side.

Kind regards
Uffe