(2014/02/28 21:41), Michael Holzheu wrote: > Hello Atsushi, > > On s390 we have the following little problem: > > We use hypervisor or stand-alone dump tools to create Linux system > dumps. These tools do not know the kernel parameter line and dump the > full physical memory. > > We use makedumpfile to filter those dumps. > > If a Linux system has specified the "mem=" parameter, the dump tools > still dump the whole phypsical memory. > > Unfortunately in "get_max_mapnr()" makedumpfile uses the ELF header to > get the maxmimum page frame number. Since this is not the correct value > in our case makedumpfile fails to filter the dump. > > We get the following error on s390 with makedumpfile version 1.5.3: > > makedumpfile -c -d 31 vmcore dump.kdump > cyclic buffer size has been changed: 22156083 => 22156032 > Excluding unnecessary pages : [ 21 %] vtop_s390x: Address too big for the number of page table levels. > readmem: Can't convert a virtual address(8000180104670) to physical address. > readmem: type_addr: 0, addr:8000180104670, size:32768 > __exclude_unnecessary_pages: Can't read the buffer of struct page. > Excluding unnecessary pages : [ 23 %] vtop_s390x: Address too big for the number of page table levels. readmem: Can't convert a > virtual address(8000180104670) to physical address. readmem: type_addr: > 0, addr:8000180104670, size:327681.5.5 __exclude_unnecessary_pages: > Can't read the buffer of struct page. > > Since version 1.5.4 makedumpfile seems to loop in __exclude_unnecessary_pages(). > > We thought about several ways to fix this problem but have not found a > good solution up to now. > > Do you have an idea how we could fix that? > > Best Regards, > Michael > At least on x86, makedumpfile appears to work well for dumps generated by sadump and virsh dump. In particular, virsh dump --memory-only generates dump in ELF, whose PT_LOAD entries are generated from RAM list managed by qemu, not managed by kernel. Looking into source code a little, max_mapnr is used only for calculating a size of two bitmaps. I guess there's any s390-specific issue. -- Thanks. HATAYAMA, Daisuke
