EXT: RE: crash: read error on type: "memory section root table"

[Agrain Patrick]

-----Message d'origine-----
De : HAGIO KAZUHITO(萩尾　一仁) <k-hagio-ab at nec.com> 
Envoyé : mercredi 6 avril 2022 09:48
À : Agrain Patrick <patrick.agrain at al-enterprise.com>
Cc : Discussion list for crash utility usage, maintenance and development <crash-utility at redhat.com>; kexec at lists.infradead.org
Objet : RE: EXT: RE: crash: read error on type: "memory section root table"

-----Original Message-----
> Hello,
> 
> Suggested trace above gives following information after a crash -d 8 command:
> <...>
> kernel NR_CPUS: 2
> <readmem: ffffffffa4925820, KVADDR, "high_memory", 8, (FOE), 
> 56017b542648>
> <read_diskdump: addr: ffffffffa4925820 paddr: 12925820 cnt: 8>
> read_diskdump: paddr/pfn: 12925820/12925 -> cache physical page: 
> 12925000
> GETBUF(328 -> 0)
> FREEBUF(0)
> GETBUF(328 -> 0)
> FREEBUF(0)
> PAGESIZE=4096
> mem_section_size = 16384
> NR_SECTION_ROOTS = 2048
> NR_MEM_SECTIONS = 524288
> SECTIONS_PER_ROOT = 256
> SECTION_ROOT_MASK = 0xff
> PAGES_PER_SECTION = 32768
> <readmem: ffffffffa4926db0, KVADDR, "mem_section", 8, (FOE), 
> 7ffd1b6bb000>
> <read_diskdump: addr: ffffffffa4926db0 paddr: 12926db0 cnt: 8>
> read_diskdump: paddr/pfn: 12926db0/12926 -> cache physical page: 
> 12926000
> <readmem: ffff904c7f7fc000, KVADDR, "memory section root table", 
> 16384, (FOE), 56017da26fd0>
> <read_diskdump: addr: ffff904c7f7fc000 paddr: 3f7fc000 cnt: 4096>
> read_diskdump: paddr/pfn: 3f7fc000/3f7fc -> cache physical page: 
> 3f7fc000
> crash: PAG3 - errno=2 r=0 pd.size=49
> read_diskdump: READ_ERROR: cannot cache page: 3f7fc000
> crash: read error: kernel virtual address: ffff904c7f7fc000  type: "memory section root table"

hmm, r=0 means end of file, can you check again whether pd.offset exceeds the dumpfile size?  If so, somehow the dumpfile is shorter than expected.

Indeed, the offset points outside the dumpfile:
Get:
crash: PAG3 - errno=2 r=0 pd.size=52 pd.offset=168956485
with a dumpfile
164820 -rw-r--r--.  1 root root  168775680  6 avril 17:23 crashdump--20220406-1713

And another one:
Get:
crash: PAG3 - errno=2 r=0 pd.size=49 pd.offset=215640649
with a dumpfile
209984 -rw-r--r--.  1 root root  215023616  1 avril 10:58 crashdump-585.000-20220401-1054

I think a RHEL-based kexec-tools does "sync" after makedumpfile, but can you check?

Actually, we are executing the makedumpfile in a script designated as init file for the second kernel. Therefore, we do not perform the sync as per core_collector.

Thanks,
Kazu

Best regards,
Patrick