On 12/12/2019 01:44 AM, Kazuhito Hagio wrote:
> Hi Pingfan,
>
>> -----Original Message-----
>>> Reading the code, I think
>>> - the issue might occur not only in refiltering, but also the first filtering
>>> with --split and --work-dir option (forced non-cyclic mode).
>>> - pefer to gather things for --split option into writeout_multiple_dumpfiles()
>>> if we can, for readability.
>> Yes, all of the cases suffer from sharing fd across processes
>>>
>>> So does the following patch work for you and your test?
>>> I could not have reproduced the issue yet.
>> I tried to fetch a machine to test. It pass 50 times test with your
>> patch. While if without this patch, it failed about 1 out of 4 times.
>
> Good. Thank you for testing.
>
>>> BTW, what do you see when the issue occurs? an error or broken dump?
>> The test case is refiltering, "makedumpfile --split -d 31
>> /root/vmcore-p9b-21 dumpfile_{1,2,3} 2>&1"
>> And it can not complete the dump.
>
> Ah, I got it. I probably could reproduce the issue:
> ---
> Excluding unnecessary pages : [100.0 %] \
> readpage_kdump_compressed: pfn(2fc1000) is excluded from vmcore.
> readmem: type_addr: 1, addr:2fc1000000, size:4096
> read_pfn: Can't get the page data.
> ...
> writeout_multiple_dumpfiles: Child process(30993) finished incompletely.(256)
>
> makedumpfile Failed.
> ---
>
> Refiltering was the factor that makedumpfile failed, but I think this bug
> also can break the dumpfile silently by excluding pages wrongly even in
> first filtering.
Yes, you are right.
>
> I guess this bug was hard to debug. Thank you so much for working on this!
Yeah, it took me some time. I had thought it should be a kernel bug
about the file{}.
> Modified your patch and pushed.
> https://sourceforge.net/p/makedumpfile/code/ci/5519b3eba68544dc484d85e9540d440d93f8c924/
>
Thanks,
Pingfan
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