Hello Abhishek, Thanks for your investigation. >I was finally able to root cause the issue that I was facing in the >kdump compressed output >generated by makedumpfile. > >While debugging "write_kdump_pages_and_bitmap_cyclic"; I came to know that >somehow "info->max_mapnr" was modified/ reduced. > >Seeing further, I could see that the "get_mem_map" function at the end >[if (!is_xen_memory())] >is attempting to change "info->max_mapnr" value based on "mem=" option. >-- in particular commit ebe2fa3a5c1e2bfac3778c0fbeca4287a934cc58. >And in my kernel command line, "mem=2G" was present, as I intended to >take dump of 2G RAM, >resulting into reduced "info->max_mapnr". Basically, this adjusting info->max_mapnr must be harmless since it just intends to ignore unused memory regions. Did you find out why adjusting info->max_mapnr causes the problem ? >So, I commented out this portion and confirmed that "info->max_mapnr" >remains same >throughout. And I was able to get kdump compressed vmcore process-able >by crash utility. This sounds like there are some valid data beyond the adjusted info->max_mapnr, is that true ? Thanks, Atsushi Kumagai >Just to summarize: >Following was the problem statement: crash was giving "seek error" >while makedumpfile generated kdump-compressed vmcore was getting analyzed. >Details: >> The output generated by makedumpfile gets processed by crash utility >> if I use following command: >> makedumpfile -E /proc/vmcore vmcore >> >> But, the output generated by following command (which I used while >> reporting the issue) gives the "seek error" while being processed by >> crash. >> makedumpfile /proc/vmcore vmcore >> >> (As a result?), output from following command gives "seek error" as >> well while being processed by crash: >> makedumpfile -c /proc/vmcore vmcore > >Following is my setup details: >>>> Kernel config: >>>> ARM64_VA_BITS_48 [=y] >>>> ARM64_PAGE_SHIFT [=12] >>>> RANDOMIZE_BASE [=n] >>>> ARM64_4K_PAGES [=y] > >> kernel: 4.12- rc5 >> yocto based rootfs: Pyro[2.3] which has kexec 2.0.14 and makedumpfile 1.6.1. >> crash: 7.1.9++ [Head: 4d517ad28acd845fe6e91360e645cf0446a4757b] > > >Thanks, >Abhishek
