RE: Preempt Violation

From: Zhu, Yi
Date: Mon Jul 19 2004 - 01:09:29 EST

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:
> It applied against 2.6.8-mm1, with only one PPC-specific reject, I
> use i386 so it doesn't matter.
> Here is another:
> Have not tested yet.
> Lee

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

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