[Crash-utility] crash 4.0-2.8 fails on 2.6.14-rc5 (EM64T)

[Dave Anderson]

Badari Pulavarty wrote:

>
> > > Now I run into next problem :( I am missing something basic.
> > >
> > > crash: read error: kernel virtual address: ffff81000000fa90  type:
> > > "pglist_data node_next"
> > >
> >
> > That's probably coming from node_table_init().  Could the pglist_data
> > list now be using per-cpu data structures?  But again, I don't understand
> > the significance of the ffff8 at the top of the address.
>
> I don't know either. I did some more digging around adding printk()
> in 2.6.10, 2.6.14-rc5 kernel where data_offset is getting set.
>
> Interestingly, allocmem() returns different types of address in 2.6.10 &
> 2.6.14-rc5 (which is causing this huge numbers).
>
> arch/x86_64/kernel/setup.c: setup_per_cpu_areas()
>
>         for_each_cpu_mask (i, cpu_possible_map) {
>                 char *ptr;
>
>                 if (!NODE_DATA(cpu_to_node(i))) {
>                         printk("cpu with no node %d, num_online_nodes %d
> \n",
>                                i, num_online_nodes());
>                         ptr = alloc_bootmem(size);
>                 } else {
>                         ptr = alloc_bootmem_node(NODE_DATA(cpu_to_node
> (i)), size);
>                 }
>                 if (!ptr)
>                         panic("Cannot allocate cpu data for CPU %d\n",
> i);
>                 cpu_pda[i].data_offset = ptr - __per_cpu_start;
> printk("i %d ptr %p cpustart %p offset %lx\n", i, ptr, __per_cpu_start,
> cpu_pda[i].data_offset);
>                 memcpy(ptr, __per_cpu_start, __per_cpu_end -
> __per_cpu_start);
>         }
>
> Here is the output:
>
> 2.6.14-rc5
>
> i 0 ptr ffff8100050eb000 cpustart ffffffff805f50a0 offset
> ffff810084af5f60
> i 1 ptr ffff8100050f3000 cpustart ffffffff805f50a0 offset
> ffff810084afdf60
>
> 2.6.10
>
> i 0 ptr 0000010005100000 cpustart ffffffff8057f0a0 offset 10084b80f60
> i 1 ptr 0000010005108000 cpustart ffffffff8057f0a0 offset 10084b88f60
> i 2 ptr 0000010005110000 cpustart ffffffff8057f0a0 offset 10084b90f60
> i 3 ptr 0000010005118000 cpustart ffffffff8057f0a0 offset 10084b98f60
> i 4 ptr 0000010005120000 cpustart ffffffff8057f0a0 offset 10084ba0f60
> i 5 ptr 0000010005128000 cpustart ffffffff8057f0a0 offset 10084ba8f60
> i 6 ptr 0000010005130000 cpustart ffffffff8057f0a0 offset 10084bb0f60
> i 7 ptr 0000010005138000 cpustart ffffffff8057f0a0 offset 10084bb8f60
>
> Don't know enough about x86-64 stuff. May be I can ask Andi Kleen
> about this change ?
>

That debug output certainly seems to pinpoint the issue at hand, doesn't it?
Very interesting...

What's strange is that the usage of the cpu_pda[i].data_offset by the
per_cpu() macro in "include/asm-x86_64/percpu.h" is unchanged.

It's probably something very simple going on here, but I don't have
any more ideas at this point.

Dave