[BUG] 2.6.26-rc2-mm1 - kernel panic at inet_create() on powerpc

Hi Andrew,

2.6.26-rc2-mm1 kernel panics on powerpc, while running ltp test over it.
I have attached the gdb output of the pc and lr registers. The patch
list_for_each_rcu-must-die-networking.patch points to changes made 
to the same lines listed by the gdb output.

 Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc000000000481fa0
cpu 0x0: Vector: 300 (Data Access) at [c0000000eae37900]
    pc: c000000000481fa0: .inet_create+0xb4/0x330
    lr: c000000000413340: .__sock_create+0x190/0x280
    sp: c0000000eae37b80
   msr: 8000000000009032
   dar: 0
 dsisr: 40010000
  current = 0xc0000000cd201500
  paca    = 0xc0000000007c3480
    pid   = 6462, comm = socket01
enter ? for help
[c0000000eae37c30] c000000000413340 .__sock_create+0x190/0x280
[c0000000eae37cf0] c0000000004137e0 .sys_socket+0x40/0x98
[c0000000eae37d90] c000000000438e18 .compat_sys_socketcall+0xc0/0x234
[c0000000eae37e30] c0000000000086b4 syscall_exit+0x0/0x40

--- Exception: c01 (System Call) at 000000000ff20484

SP (ffc8f770) is in userspace


0xc000000000481fa0 is in inet_create (net/ipv4/af_inet.c:290).
285             /* Look for the requested type/protocol pair. */
286             answer = NULL;
287     lookup_protocol:
288             err = -ESOCKTNOSUPPORT;
289             rcu_read_lock();
290             list_for_each_entry_rcu(answer, &inetsw[sock->type], list) {
291
292                     /* Check the non-wild match. */
293                     if (protocol == answer->protocol) {
294                             if (protocol != IPPROTO_IP)


0xc000000000413340 is in __sock_create (net/socket.c:1171).
1166                    goto out_release;
1167
1168            /* Now protected by module ref count */
1169            rcu_read_unlock();
1170
1171            err = pf->create(net, sock, protocol);
1172            if (err < 0)
1173                    goto out_module_put;
1174
1175            /*

-- 
Thanks & Regards,
Kamalesh Babulal,
Linux Technology Center,
IBM, ISTL.

On Wed, May 14, 2008 at 09:04:07PM +0530, Kamalesh Babulal wrote:

Hi Andrew,

2.6.26-rc2-mm1 kernel panics on powerpc, while running ltp test over it.
I have attached the gdb output of the pc and lr registers. The patch
list_for_each_rcu-must-die-networking.patch points to changes made 
to the same lines listed by the gdb output.

Hmmm....  Does the panic go away when this patch is reverted?

						Thanx, Paul

11 more quoted lines

On Wed, May 14, 2008 at 09:07:05AM -0700, Paul E. McKenney wrote:

On Wed, May 14, 2008 at 09:04:07PM +0530, Kamalesh Babulal wrote:

quoted

Hi Andrew,

2.6.26-rc2-mm1 kernel panics on powerpc, while running ltp test over it.
I have attached the gdb output of the pc and lr registers. The patch
list_for_each_rcu-must-die-networking.patch points to changes made 
to the same lines listed by the gdb output.

Hmmm....  Does the panic go away when this patch is reverted?

Yes.

On Thu, May 15, 2008 at 12:05:46AM +0400, Alexey Dobriyan wrote:

On Wed, May 14, 2008 at 09:07:05AM -0700, Paul E. McKenney wrote:

quoted

On Wed, May 14, 2008 at 09:04:07PM +0530, Kamalesh Babulal wrote:

quoted

Hi Andrew,

2.6.26-rc2-mm1 kernel panics on powerpc, while running ltp test over it.
I have attached the gdb output of the pc and lr registers. The patch
list_for_each_rcu-must-die-networking.patch points to changes made 
to the same lines listed by the gdb output.

Hmmm....  Does the panic go away when this patch is reverted?

Yes.

OK, am awake now, apologies for my confusion.  Not sure -what- state
I was in when generating and validating the original...

							Thanx, Paul