Messages in this thread | | | From | John Ogness <> | Subject | Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking | Date | Sat, 30 Apr 2022 18:06:01 +0206 |
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On 2022-04-29, Marek Szyprowski <m.szyprowski@samsung.com> wrote: > The same issue happens if I boot with init=/bin/bash
Very interesting. Since you are seeing all the output up until you try doing something, I guess receiving UART data is triggering the issue.
> I found something really interesting. When lockup happens, I'm still > able to log via ssh and trigger any magic sysrq action via > /proc/sysrq-trigger.
If you boot the system and directly login via ssh (without sending any data via serial), can you trigger printk output on the UART? For example, with:
echo hello > /dev/kmsg
(You might need to increase your loglevel to see it.)
> It turned out that the UART console is somehow blocked, but it > receives and buffers all the input. For example after issuing "echo > >/proc/sysrq-trigger" from the ssh console, the UART console has been > updated and I see the magic sysrq banner and then all the commands I > blindly typed in the UART console! However this doesn't unblock the > console.
sysrq falls back to direct printing. This would imply that the kthread printer is somehow unable to print.
> Here is the output of 't' magic sys request: > > https://pastebin.com/fjbRuy4f
It looks like the call trace for the printing kthread (pr/ttyAML0) is corrupt.
Could you post your kernel config?
John
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