Hi Tao,

On 10/7/2025 1:11 AM, Tao Liu wrote:
> On Tue, Sep 30, 2025 at 8:18 PM lijiang <[email protected]> wrote:
>>
>> On Tue, Sep 30, 2025 at 3:01 PM Mikhail Zaslonko <[email protected]> 
>> wrote:
>>>
>>> Hello,
>>>
>>> On 9/30/2025 4:53 AM, lijiang wrote:
>>>> On Tue, Sep 30, 2025 at 2:18 AM Mikhail Zaslonko <[email protected]>
>>>> wrote:
>>>>
>>>>> Hi Lianbo,
>>>>>
>>>>> It seems we have a problem printing disassembly blocks in the log after
>>>>> this patch (at least on s390).
>>>>> See number of empty lines printed below.
>>>>>
>>>>
>>>> Can you try it with the following two patches?
>>>> [1]
>>>> https://www.mail-archive.com/[email protected]/msg01621.html
>>> This patch is present on crash master, doesnt affect the issue.
>>>> [2]
>>>> https://www.mail-archive.com/[email protected]/msg01636.html
>>>>
>>> This one helps indeed! At least I do not se the blanks lines in my scenario.
>>> BUT, if I use 'log -R' the blank lines are back again!
>>
>>
>> Thanks for the information, Mikhail.
>> Let me see how to debug this(although I can not reproduce it on s390x).
> 
> I didn't reproduce the issue on my s390x machine either, maybe sharing
> the vmcore to us can help.

I'm not sure I'm allowed to send this data outside.

I think the problem takes place for the logs printed with pr_cont() by the
kernel (e.g. show_code() of arch/s390/kernel/dis.c for printing disassembly as
in my sample).

> 
> Thanks,
> Tao Liu
> 
>>
>> Thanks
>> Lianbo
>>
>>>
>>>
>>>>
>>>>> Before the patch:
>>>>>   [   21.408784] Krnl GPRS: 000002aa3780c000 0000000000238c00
>>>>> 0000000015800000 0000000000001000
>>>>>   [   21.408787]            0000000008e30000 00000000b0001000
>>>>> 0000000000000000 0000000000000a55
>>>>>   [   21.408790]            0000000004c52300 000002aa3780c000
>>>>> 00000000084281d0 0000038000bfbd28
>>>>>   [   21.408794]            00000000075e9500 0000000004c52300
>>>>> 0000038000bfbbf0 0000038000bfbb90
>>>>>   [   21.408860] Krnl Code: 000000000e0acf48: c05fb0001000        llilf
>>>>>  %r5,2952794112
>>>>>                             000000000e0acf4e: ec4100b30659        risbgn
>>>>> %r4,%r1,0,179,6
>>>>>                            #000000000e0acf54: 0e24                mvcl
>>>>> %r2,%r4
>>>>>                            >000000000e0acf56: a7280000            lhi
>>>>>  %r2,0
>>>>>                             000000000e0acf5a: eb6ff0a80004        lmg
>>>>>  %r6,%r15,168(%r15)
>>>>>                             000000000e0acf60: b9140022            lgfr
>>>>> %r2,%r2
>>>>>                             000000000e0acf64: 07fe                bcr
>>>>>  15,%r14
>>>>>                             000000000e0acf66: 47000700            bc
>>>>> 0,1792
>>>>>   [   21.408883] Call Trace:
>>>>>
>>>>> After the patch:
>>>>>   [   21.408784] Krnl GPRS: 000002aa3780c000 0000000000238c00
>>>>> 0000000015800000 0000000000001000
>>>>>   [   21.408787]            0000000008e30000 00000000b0001000
>>>>> 0000000000000000 0000000000000a55
>>>>>   [   21.408790]            0000000004c52300 000002aa3780c000
>>>>> 00000000084281d0 0000038000bfbd28
>>>>>   [   21.408794]            00000000075e9500 0000000004c52300
>>>>> 0000038000bfbbf0 0000038000bfbb90
>>>>>   [   21.408860]
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>                  Krnl Code: 000000000e0acf48: c05fb0001000        llilf
>>>>>  %r5,2952794112
>>>>>   [   21.408883] Call Trace:
>>>>>
>>>>> I think your approach of storing printable characters in the buffer with
>>>>> the intention to modify it
>>>>> afterwards (see [1] below) instead of writing it character wise does not
>>>>> work when the input data
>>>>> contains several lines. Those '\n' are written one by one, what leads to
>>>>> the result shown above.
>>>>> You should probably buffer and 'demangle' each line separately.
>>>>>
>>>>
>>>> Looks like different issues.  Can you share your vmcore and vmlinux with
>>>> me? I did not reproduce it.
>>>
>>>
>>>>
>>>> Thanks
>>>> Lianbo
>>>>
>>>>>
>>>>>
>>>>
>>>
> 
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