[Crash-utility] x86 remap allocator in kernel 3.0

[Dave Anderson]

----- Original Message -----
> On 01/11/2012 06:53 AM, Petr Tesarik wrote:
> > Dne Út 10. ledna 2012 19:23:24 Petr Tesarik napsal(a):
> >> Dne Út 10. ledna 2012 19:14:32 Petr Tesarik napsal(a):
> ... [ cut ] ...
> >> crash>  vtop f2800080
> >> VIRTUAL   PHYSICAL
> >> f2800080  1fde00080
> >>
> >> PAGE DIRECTORY: c08ed000
> >>    PGD: c08ed018 =>  8ea001
> >>    PMD:   8eaca0 =>  80000001fde001e3
> >>   PAGE: 1fde00000  (2MB)
> >>
> >>        PTE         PHYSICAL   FLAGS
> >> 80000001fde001e3  1fde00000
> >>  (PRESENT|RW|ACCESSED|DIRTY|PSE|GLOBAL|NX)
> >>
> >>    PAGE     PHYSICAL   MAPPING    INDEX CNT FLAGS
> >
> > BTW the data from struct page is really missing here. I traced this down to an
> > integer overflow in dump_memory_nodes():
> ... [ cut ] ...
> > David (Mair), could you address this, as already discussed in private mails,
> > please?
> 
> The attached patch fixes this for me.

Hmmm, not so much for me...

When I test the patch on RHEL5, RHEL6 and Fedora x86 kernels, the
command always fails like this:

crash> kmem -n
NODE    SIZE    PGLIST_DATA   BOOTMEM_DATA   NODE_ZONES 
  0    262075     c0a3a680      c0aa5ce8      c0a3a680  
                                              c0a3b1c0
                                              c0a3bd00
                                              c0a3c840
MEM_MAP      START_PADDR    START_MAPNR
Segmentation fault
$
 
I haven't look into it, and this is probably not related:

cc -c -g -DX86 -m32 -D_FILE_OFFSET_BITS=64 -DGDB_7_3_1  memory.c -Wall -O2 -Wstrict-prototypes -Wmissing-prototypes -fstack-protector 
memory.c: In function 'dump_memory_nodes':
memory.c:13410: warning: cast to pointer from integer of different size
memory.c:13199: warning: 'node_start_paddr' may be used uninitialized in this function

But from under gdb:

crash> kmem -n
[Detaching after fork from child process 16870.]

Program received signal SIGSEGV, Segmentation fault.
0x0809cd94 in mkstring (s=0xffe8a8bc "  c0a3a680  ", size=16, flags=133, opt=0x1000 <Address 0x1000 out of bounds>)
    at tools.c:1620
1620                    sprintf(s, "%llx", *((ulonglong *)opt));
(gdb) bt
#0  0x0809cd94 in mkstring (s=0xffe8a8bc "  c0a3a680  ", size=16, flags=133, opt=0x1000 <Address 0x1000 out of bounds>)
    at tools.c:1620
#1  0x080b1ad7 in dump_memory_nodes (initialize=0) at memory.c:13406
#2  0x080d46cc in cmd_kmem () at memory.c:4221
#3  0x080941b8 in exec_command () at main.c:751
#4  0x08093fe6 in main_loop () at main.c:699
#5  0x081db622 in current_interp_command_loop ()
#6  0x081dbf01 in captured_command_loop ()
#7  0x081db0a4 in catch_errors ()
#8  0x081dce07 in captured_main ()
#9  0x081db0a4 in catch_errors ()
#10 0x081dce49 in gdb_main ()
#11 0x081dce99 in gdb_main_entry ()
#12 0x08116668 in gdb_main_loop (argc=2, argv=0xffe8d494) at gdb_interface.c:75
#13 0x08093ce0 in main (argc=3, argv=0xffe8d494) at main.c:603
(gdb) p opt
$1 = 0x1000 <Address 0x1000 out of bounds>
(gdb) 

I thought it might be just an x86 issue, but it also fails
the same way on RHEL5, RHEL6 and Fedora x86_64 kernels.

Dave