Re: [VLAN] Bad: scheduling while atomic! in 2.6.8.1]

[Ben Greear <greearb@xxxxxxxxxxxxxxx>]

Andre Correa wrote:
> Hi, I set up a Linux box as a firewall with 4 NICs (3C905) on a Dell
> with 2.6.8.1 and iptables 1.2.11. 3 NICs have several IP addresses and
> the 4th has 4 VLANs associated. This box is plugged on Cisco switches.
>
> Everything was fine, firewalling OK, until I plugged the 4th NIC. When
> traffic start to flow the box logs a _LOT_ of errors on syslog:
Mr. Hemminger recently added some RCU locking changes to VLAN.
That said, I don't see any mention of vlan in the stack traces
below, so it could be that there is some other problem.

I'm forwarding this to the netdev mailing list as well.


> <snip>
> Sep  1 03:58:48 fw01 kernel: bad: scheduling while atomic!
> Sep  1 03:58:48 fw01 kernel:  [<c028bddc>] schedule+0x3c/0x428
> Sep  1 03:58:48 fw01 kernel:  [<c0230c74>] sys_socketcall+0x150/0x1f4
> Sep  1 03:58:48 fw01 kernel:  [<c0103c0e>] work_resched+0x5/0x16
> Sep  1 03:58:48 fw01 kernel: bad: scheduling while atomic!
> Sep  1 03:58:48 fw01 kernel:  [<c028bddc>] schedule+0x3c/0x428
> Sep  1 03:58:48 fw01 kernel:  [<c0232a63>] __kfree_skb+0xd3/0xd8
> Sep  1 03:58:48 fw01 kernel:  [<c028c5d4>] schedule_timeout+0x14/0xb0
> Sep  1 03:58:48 fw01 kernel:  [<c02862ac>] unix_wait_for_peer+0xac/0xc8
> Sep  1 03:58:48 fw01 kernel:  [<c010f348>] 
> autoremove_wake_function+0x0/0x40
> Sep  1 03:58:48 fw01 kernel:  [<c010f348>] 
> autoremove_wake_function+0x0/0x40
> Sep  1 03:58:48 fw01 kernel:  [<c0286d4f>] unix_dgram_sendmsg+0x39b/0x4b0
> Sep  1 03:58:48 fw01 kernel:  [<c022f6b1>] sock_aio_write+0x101/0x10c
> Sep  1 03:58:48 fw01 kernel:  [<c013d6e6>] do_sync_write+0x7a/0xac
> Sep  1 03:58:48 fw01 kernel:  [<c023298b>] kfree_skbmem+0x17/0x1c
> Sep  1 03:58:48 fw01 kernel:  [<c0232a63>] __kfree_skb+0xd3/0xd8
> Sep  1 03:58:48 fw01 kernel:  [<c013d7cd>] vfs_write+0xb5/0xd4
> Sep  1 03:58:48 fw01 kernel:  [<c013d898>] sys_write+0x40/0x6c
> Sep  1 03:58:48 fw01 kernel:  [<c0103be7>] syscall_call+0x7/0xb
> Sep  1 03:58:48 fw01 kernel: bad: scheduling while atomic!
> Sep  1 03:58:48 fw01 kernel:  [<c028bddc>] schedule+0x3c/0x428
> Sep  1 03:58:49 fw01 kernel:  [<c0230c74>] sys_socketcall+0x150/0x1f4
> Sep  1 03:58:49 fw01 kernel:  [<c0103c0e>] work_resched+0x5/0x16
> Sep  1 03:58:49 fw01 kernel: bad: scheduling while atomic!
> Sep  1 03:58:49 fw01 kernel:  [<c028bddc>] schedule+0x3c/0x428
> Sep  1 03:58:49 fw01 kernel:  [<c0232a63>] __kfree_skb+0xd3/0xd8
> Sep  1 03:58:49 fw01 kernel:  [<c028c5d4>] schedule_timeout+0x14/0xb0
> Sep  1 03:58:49 fw01 kernel:  [<c02862ac>] unix_wait_for_peer+0xac/0xc8
> Sep  1 03:58:49 fw01 kernel:  [<c010f348>] 
> autoremove_wake_function+0x0/0x40
> Sep  1 03:58:49 fw01 kernel:  [<c010f348>] 
> autoremove_wake_function+0x0/0x40
> Sep  1 03:58:49 fw01 kernel:  [<c0286d4f>] unix_dgram_sendmsg+0x39b/0x4b0
> Sep  1 03:58:49 fw01 kernel:  [<c022f6b1>] sock_aio_write+0x101/0x10c
> Sep  1 03:58:49 fw01 kernel:  [<c013d6e6>] do_sync_write+0x7a/0xac
> Sep  1 03:58:49 fw01 kernel:  [<c023298b>] kfree_skbmem+0x17/0x1c
> Sep  1 03:58:49 fw01 kernel:  [<c0232a63>] __kfree_skb+0xd3/0xd8
> Sep  1 03:58:49 fw01 kernel:  [<c013d7cd>] vfs_write+0xb5/0xd4
> Sep  1 03:58:49 fw01 kernel:  [<c013d898>] sys_write+0x40/0x6c
> Sep  1 03:58:49 fw01 kernel:  [<c0103be7>] syscall_call+0x7/0xb
> <snip>
>
> I got more then 110Mb of it in ~2 hours of tests. Shutting down
> interface doesn't stop it, just a reboot takes the machine back to its
> normal state, if cable is unplugged.
>
> I've tested NIC, cable, PCI slot, switch port, switch and even changed
> the box itself, but nothing helped. When I take VLAN down, on Cisco
> switch, no errors are logged. If I go back to 2.6.7 + VLAN, no errors
> too, all OK.
>
> It seens to be related to VLAN on 2.6.8.1 only. Searching kernel source
> I found that it comes from kernel/sched.c, but it doesn't tells me much.
>
> <snip>
>         /*
>          * Test if we are atomic.  Since do_exit() needs to call into
>          * schedule() atomically, we ignore that path for now.
>          * Otherwise, whine if we are scheduling when we should not be.
>          */
>         if (likely(!(current->state & (TASK_DEAD | TASK_ZOMBIE)))) {
>                 if (unlikely(in_atomic())) {
>                         printk(KERN_ERR "bad: scheduling while atomic!\n");
>                         dump_stack();
>                 }
>         }
> <snip>
>
> Does anybody can help on it?! Does it look like a bug or what?
>
> Any help is appreciated.
>
> tks
>
> Andre
>
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--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com