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

From: Paul E. McKenney
Date: Wed May 14 2008 - 12:07:27 EST


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.
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