On Wed, 12 Mar 2014 06:01:47 +0000
Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp> wrote:
> >(2014/02/28 21:41), Michael Holzheu wrote:
> >> Hello Atsushi,
[snip]
> >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.
>
> On second thought, Michael's log looks strange.
>
> >> 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.
>
> This message was shown during translating the virtual address of mem_map
> to the physical address:
>
> __exclude_unnecessary_pages():
>
> if (!readmem(VADDR, mem_map,
> page_cache + (index_pg * SIZE(page)),
> SIZE(page) * pfn_mm)) {
> ERRMSG("Can't read the buffer of struct page.\n");
> return FALSE;
> }
>
> However, this should succeed even if mem= was specified because the
> corresponding page table must exist in the memory image since it was
> used by kernel actually. The address translation logic may have an issue.
To be honest I don't really understand what happens when the error occurs.
My test is a 1 TiB dump of a Linux system that has set mem=1G.
With makedumpfile 1.5.3 I see the following stack backtrace:
(gdb) bt
#0 vtop_s390x (vaddr=2251803034918936) at ./arch/s390x.c:236
#1 0x000000008001de44 in vaddr_to_paddr_s390x (vaddr=2251803034918936)
at ./arch/s390x.c:300
#2 0x000000008001fb50 in readmem (type_addr=0, addr=2251803034918936,
bufptr=0x3ffffff6cf0, size=32768) at makedumpfile.c:349
#3 0x0000000080034cf2 in __exclude_unnecessary_pages (
mem_map=2251803034918936, pfn_start=16777216, pfn_end=16842752)
at makedumpfile.c:4189
#4 0x0000000080035716 in exclude_unnecessary_pages_cyclic ()
at makedumpfile.c:4349
#5 0x00000000800358e4 in update_cyclic_region (pfn=0) at makedumpfile.c:4380
#6 0x00000000800384e0 in get_num_dumpable_cyclic () at makedumpfile.c:5060
#7 0x0000000080036850 in create_dump_bitmap () at makedumpfile.c:4585
#8 0x00000000800429c8 in create_dumpfile () at makedumpfile.c:7533
#9 0x00000000800490fc in main (argc=5, argv=0x3fffffff3d8)
at makedumpfile.c:8651
Looks like makdumpfile wants to read a virtual address 2251803034918936
(hex 0x80000C0002018) which can't be resolved by the three level kernel
page table (max is 4 TiB here).
In the __exclude_unnecessary_pages() function the variables have the
following values:
(gdb) print pfn_end
$1 = 16842752
(gdb) print pfn
$2 = 16777216
(gdb) print pfn_start
$3 = 16777216
(gdb) print mem_map
$4 = 2251803034918936
I would appreciate any hints!
Michael
