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

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

[Kamalesh Babulal]

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.

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

[Paul E. McKenney]

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

>  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.

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

[Alexey Dobriyan]

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:
> > 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.

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

[Paul E. McKenney]

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:
> > 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?
> 
> Yes.

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

							Thanx, Paul