Re: [BUGFIX] trace, fix ring_buffer_read_page reading out of pageboundary

From: Steven Rostedt
Date: Fri Aug 06 2010 - 12:51:11 EST

Hi Huang,

Sorry for the late reply, I just got back from vacation. Note, it is
best to send to my goodmis account since I do not always check my RH
email. But ironically, I'm going through my RH email first, so I got
this first ;-)

On Wed, 2010-07-28 at 14:14 +0800, Huang Ying wrote:
> With the configuration: CONFIG_DEBUG_PAGEALLOC=y and Shaohua's patch:
> [PATCH]x86: make spurious_fault check correct pte bit
> Function call graph trace as follow will trigger page fault.
> # cd /sys/kernel/debug/tracing/
> # echo function_graph > current_tracer
> # cat per_cpu/cpu1/trace_pipe_raw > /dev/null

Yep! I can trigger it too. I'll pull in your patch, test it and send it
out for 2.6.36 and stable.


-- Steve

> BUG: unable to handle kernel paging request at ffff880006e99000
> IP: [<ffffffff81085572>] rb_event_length+0x1/0x3f
> PGD 1b19063 PUD 1b1d063 PMD 3f067 PTE 6e99160
> Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
> last sysfs file: /sys/devices/virtual/net/lo/operstate
> CPU 1
> Modules linked in:

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