[2.6.5] Bad scheduling while atomic

[2.6.5] Bad scheduling while atomic

[Paul Rolland]

Hello,

I have these in my logs :

bad: scheduling while atomic!
Call Trace:
 [<c011aa54>] schedule+0x59e/0x5a4
 [<c0118575>] pte_alloc_one+0x55/0x68
 [<c011ad6d>] wait_for_completion+0x91/0xe6
 [<c011aaaa>] default_wake_function+0x0/0x12
 [<c011aaaa>] default_wake_function+0x0/0x12
 [<c012dc05>] synchronize_kernel+0x31/0x3c
 [<c012dbca>] wakeme_after_rcu+0x0/0xa
 [<c04131ef>] unregister_netdevice+0x141/0x27a
 [<c0419f8b>] rtmsg_ifinfo+0x91/0xda
 [<c03316c8>] lapbeth_device_event+0xa6/0xf0
 [<c0129dc5>] notifier_call_chain+0x27/0x3e
 [<c041320f>] unregister_netdevice+0x161/0x27a
 [<c0330cf2>] tun_chr_close+0xe8/0xf2
 [<c0330c0a>] tun_chr_close+0x0/0xf2
 [<c0153340>] __fput+0x120/0x132
 [<c015199b>] filp_close+0x59/0x86
 [<c0151a2c>] sys_close+0x64/0x98
 [<c0108b17>] syscall_call+0x7/0xb

Any other info that could help someone ?

Regards,
Paul

Re: [2.6.5] Bad scheduling while atomic

[Stephen Hemminger]

Bring up/down network devices with lapbether causes scheduling while
atomic (if preempt enabled).

The calls to rcu_read_lock are unnecessary since lapb_device_event 
is called from notifier with the rtnetlink semaphore held, it is
already protected from the labp_devices list changing.

Patch against 2.6.6-rc1

diff -Nru a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
--- a/drivers/net/wan/lapbether.c	Fri Apr 16 11:00:35 2004
+++ b/drivers/net/wan/lapbether.c	Fri Apr 16 11:00:35 2004
@@ -392,6 +392,8 @@
 
 /*
  *	Handle device status changes.
+ *
+ * Called from notifier with RTNL held.
  */
 static int lapbeth_device_event(struct notifier_block *this,
 				unsigned long event, void *ptr)
@@ -402,7 +404,6 @@
 	if (!dev_is_ethdev(dev))
 		return NOTIFY_DONE;
 
-	rcu_read_lock();
 	switch (event) {
 	case NETDEV_UP:
 		/* New ethernet device -> new LAPB interface	 */
@@ -422,7 +423,6 @@
 			lapbeth_free_device(lapbeth);
 		break;
 	}
-	rcu_read_unlock();
 
 	return NOTIFY_DONE;
 }

Re: [2.6.5] Bad scheduling while atomic

[David S. Miller]

On Fri, 16 Apr 2004 13:16:33 -0700
Stephen Hemminger <shemminger@osdl.org> wrote:

> Bring up/down network devices with lapbether causes scheduling while
> atomic (if preempt enabled).
> 
> The calls to rcu_read_lock are unnecessary since lapb_device_event 
> is called from notifier with the rtnetlink semaphore held, it is
> already protected from the labp_devices list changing.

Applied, thanks Stephen.

RE: [2.6.5] Bad scheduling while atomic

[Paul Rolland]

Thanks Stephen for being so fast !

Regards,
Paul

Paul Rolland, rol(at)as2917.net
ex-AS2917 Network administrator and Peering Coordinator

--

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"Some people dream of success... while others wake up and work hard at it" 

  

> -----Message d'origine-----
> De : linux-kernel-owner@vger.kernel.org 
> [mailto:linux-kernel-owner@vger.kernel.org] De la part de 
> Stephen Hemminger
> Envoyé : vendredi 16 avril 2004 22:17
> À : David S. Miller
> Cc : Paul Rolland; linux-kernel@vger.kernel.org; netdev@oss.sgi.com
> Objet : Re: [2.6.5] Bad scheduling while atomic
> 
> Bring up/down network devices with lapbether causes scheduling while
> atomic (if preempt enabled).
> 
> The calls to rcu_read_lock are unnecessary since lapb_device_event 
> is called from notifier with the rtnetlink semaphore held, it is
> already protected from the labp_devices list changing.
> 
> Patch against 2.6.6-rc1
> 
> diff -Nru a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
> --- a/drivers/net/wan/lapbether.c	Fri Apr 16 11:00:35 2004
> +++ b/drivers/net/wan/lapbether.c	Fri Apr 16 11:00:35 2004
> @@ -392,6 +392,8 @@
>  
>  /*
>   *	Handle device status changes.
> + *
> + * Called from notifier with RTNL held.
>   */
>  static int lapbeth_device_event(struct notifier_block *this,
>  				unsigned long event, void *ptr)
> @@ -402,7 +404,6 @@
>  	if (!dev_is_ethdev(dev))
>  		return NOTIFY_DONE;
>  
> -	rcu_read_lock();
>  	switch (event) {
>  	case NETDEV_UP:
>  		/* New ethernet device -> new LAPB interface	 */
> @@ -422,7 +423,6 @@
>  			lapbeth_free_device(lapbeth);
>  		break;
>  	}
> -	rcu_read_unlock();
>  
>  	return NOTIFY_DONE;
>  }
> -
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