Re: 2.6.33: ftrace triggers soft lockup

From: Li Zefan
Date: Sun Mar 14 2010 - 21:45:31 EST


Steven Rostedt wrote:
> On Fri, 2010-03-12 at 21:07 -0500, Steven Rostedt wrote:
>> On Tue, 2010-03-09 at 11:38 +0800, Li Zefan wrote:
>>
>>> The segfault is from userspace. This is a segfault I just got:
>>>
>>> ftrace_stack_ma[14989]: segfault at fe2e ip 00000000004474c0 sp 00007fffb97e38c0 error 4 in bash[400000+d1000]
>> Li and Lai,
>>
>> Thanks a lot for reporting all this, and writing the ftrace_stress_test.
>> I've fixed all the bugs that it has reported (to my knowledge) and after
>> a little more testing I will soon be sending a patch series out.
>
> Li,
>
> I ran your test for 13 hours on three different machines. I did not hit
> any more errors. Although I see a lockdep warning (not a locking problem
> but the WARN_ON in fork.c is triggering). I'll look into that on Monday.
>

As I said in the offline mail, this warning is caused by global trace_clock,
and I sent a fix sometime ago:

http://lkml.org/lkml/2009/12/21/4

> Please take the new patches that Ingo just pushed to Linus, if you find
> any more bugs, please let me know right away.
>

Thanks for the fixes!

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