Re: HEAD instability on Xen

[Antti Kantee <pooka%cs.hut.fi@localhost>]

On Sun Nov 18 2007 at 21:19:15 +0100, Manuel Bouyer wrote:
> Hi,
> I've tested a kernel built from HEAD (which I didn't do for some time) and
> seeing panics when starting xend (this dom0 has only 64Mb RAM allocated).
> It's always a uvm_fault() on a kernel address, but the fault instruction
> varies. Here's a sample of a panic:
> 
> Starting xend.
> uvm_fault(0xc09605c0, 0xc8028000, 1) -> 0xe
> fatal page fault in supervisor mode
> trap type 6 code 0 eip c03c8bdd cs 9 eflags 10246 cr2 0 ilevel 0
> kernel: supervisor trap page fault, code=0
> Stopped in pid 169.1 (python2.4) at     netbsd:uvm_map_lookup_entry+0x4d:     
>   cmpl     %edi,0x20(%ebx)
> db> tr
> uvm_map_lookup_entry(c5db0ac4,8063000,c7fa6690,1,0) at 
> netbsd:uvm_map_lookup_entry+0x4d
> uvm_fault_internal(c5db0ac4,8063000,2,0,c04db079) at 
> netbsd:uvm_fault_internal+0xdd
> trap() at netbsd:trap+0x415

Looks awfully lot like corrupted vm_maps for the newly created process.
But I don't know why this would be related to xen and specifically
starting xend.

What do you mean that the fault instruction varies?  Is it still always
trying to access a vm_map_entry?  I'm guessing the above example was
from line 1556 in uvm_map.c.

Anyway, just guessing really.

-- 
Antti Kantee <pooka%iki.fi@localhost>                     Of course he runs 
NetBSD
http://www.iki.fi/pooka/                          http://www.NetBSD.org/
    "la qualité la plus indispensable du cuisinier est l'exactitude"