RE: Preempt Violation

[Zhu, Yi]

linux-kernel-owner@xxxxxxxxxxxxxxx wrote:
> On Fri, 2004-07-16 at 20:06, Gabriel Devenyi wrote:
>> This one looks particularly nasty.
>> 
>> 20ms non-preemptible critical section violated 4 ms preempt
>> threshold starting a
> 
>> t sys_ioctl+0x42/0x260 and ending at sys_ioctl+0xbd/0x260
>> [<c015881d>] sys_ioctl+0xbd/0x260  [<c0116510>]
>> dec_preempt_count+0x110/0x120  [<c015881d>] sys_ioctl+0xbd/0x260
>> [<c0103e95>] sysenter_past_esp+0x52/0x71
> 
> Yes, it looks like there are serious issues with ioctl.
> 
> Are you using either of the recent patches to fully daemonize
> softirqs? This should help a lot.  I am using this one:
> 
> http://lkml.org/lkml/2004/7/13/125
> 
> It applied against 2.6.8-mm1, with only one PPC-specific reject, I
> use i386 so it doesn't matter. 
> 
> Here is another:
> 
> http://lkml.org/lkml/2004/7/13/152
> 
> Have not tested yet.
> 
> Lee

ioctl is called with the BKL held, which will disable preempt.
I don't think the patch helps.

Thanks,
-yi
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