Re: [PATCH v3 1/2] Allow cpu backtraces to be written into ringbuffer during panic

From: takakura
Date: Thu Aug 15 2024 - 06:51:40 EST


Hi Petr and John,

On Tue 2024-08-13 13:48, Petr Mladek wrote:
>On Mon 2024-08-12 16:27:03, takakura@xxxxxxxxxxxxx wrote:
>> From: Ryo Takakura <takakura@xxxxxxxxxxxxx>
>>
>> commit 779dbc2e78d7 ("printk: Avoid non-panic CPUs writing
>> to ringbuffer") disabled non-panic CPUs to further write messages to
>> ringbuffer after panicked.
>>
>> Since the commit, non-panicked CPU's are not allowed to write to
>> ring buffer after panicked and CPU backtrace which is triggered
>> after panicked to sample non-panicked CPUs' backtrace no longer
>> serves its function as it has nothing to print.
>>
>> Fix the issue by allowing non-panicked CPUs to write into ringbuffer
>> while CPU backtrace is in flight.
>>
>> Fixes: 779dbc2e78d7 ("printk: Avoid non-panic CPUs writing to ringbuffer")
>> Signed-off-by: Ryo Takakura <takakura@xxxxxxxxxxxxx>
>> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
>
>JFYI, I have pushed this patch into printk/linux.git, branch for-6.11-fixup.
>I am going to create pull request after it spends at least one or two
>days in linux-next.

Thanks!!

>The 2nd patch is more complicated. It depends on another patchset
>integrating con->write_atomic() callback.
>
>Best Regards,
>Petr

Sincerely,
Ryo Takakura