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.

I guess this bug was hard to debug. Thank you so much for working on this!
Modified your patch and pushed.
https://sourceforge.net/p/makedumpfile/code/ci/5519b3eba68544dc484d85e9540d440d93f8c924/

Thanks,
Kazu




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