Re: [BUG] WARNING: at kernel/trace/ring_buffer.c:3420

[Li Zefan <lizf@cn.fujitsu.com>]

Steven Rostedt wrote:
> On Mon, 2010-03-08 at 14:04 +0800, Li Zefan wrote:
>> While running a ftrace test, a kernel warning showed up. The bug is not so
>> easy to reproduce, normally it takes 30 mins to 2 hours.
> 
> What test are you running? Can you share it?
> 

The test runs 10+ processes, reading/writing files in debugfs/tracing/
simultaneously.

I'll send it to you in a private mail.

>> After revering 3c05d7482777f15e71bb4cb1ba78dee2800dfec6, I ran the test
>> for 15 hours, and the bug seems disapeared.
> 
> So basically, you are reading both the trace and trace_pipe (or
> trace_pipe_raw) at the same time?
> 

reading trace, yes. reading trace_pipe, no.

Actualy we don't see how this commit relates to the bug.
I'll run the test again to be sure on this.

> -- Steve
> 
>> ------------[ cut here ]------------
>> WARNING: at kernel/trace/ring_buffer.c:3420 ring_buffer_reset_cpu+0x5a/0x9c()
>> Hardware name: PRIMERGY                      
>> Modules linked in: ipt_MASQUERADE iptable_nat nf_nat bridge stp llc deflate zlib_deflate ctr camellia cast5 rmd160 crypto_null ccm serpent blowfish twofish_x86_64 twofish_common ecb xcbc cbc sha256_generic sha512_generic des_generic cryptd aes_x86_64 aes_generic ah6 ah4 esp6 esp4 xfrm4_mode_beet xfrm4_tunnel tunnel4 xfrm4_mode_tunnel xfrm4_mode_transport xfrm6_mode_transport xfrm6_mode_beet ipcomp ipcomp6 xfrm_ipcomp xfrm6_tunnel tunnel6 af_key autofs4 sunrpc ipv6 dm_mirror dm_region_hash dm_log dm_multipath uinput i5k_amb hwmon e1000e i5000_edac edac_core iTCO_wdt iTCO_vendor_support shpchp i2c_i801 i2c_core serio_raw pcspkr pata_acpi ata_generic mptsas mptscsih ata_piix mptbase scsi_transport_sas dm_mod [last unloaded: speedstep_lib]
>> Pid: 2108, comm: ftrace_current_ Tainted: G        W  2.6.33-tip+ #2
>> Call Trace:
>>  [<ffffffff8104ebd0>] warn_slowpath_common+0x7c/0x94
>>  [<ffffffff8104ebfc>] warn_slowpath_null+0x14/0x16
>>  [<ffffffff810a50f5>] ring_buffer_reset_cpu+0x5a/0x9c
>>  [<ffffffff810aa3f0>] tracing_reset_online_cpus+0x4a/0x79
>>  [<ffffffff810aa434>] tracer_init+0x15/0x20
>>  [<ffffffff810aa601>] tracing_set_tracer+0x1c2/0x1e7
>>  [<ffffffff810d9847>] ? might_fault+0x5c/0xac
>>  [<ffffffff810aa6b2>] tracing_set_trace_write+0x8c/0xbc
>>  [<ffffffff810a8e79>] ? trace_buffer_lock_reserve+0x21/0x56
>>  [<ffffffff810a95ce>] ? trace_current_buffer_lock_reserve+0x16/0x18
>>  [<ffffffff813ef135>] ? retint_swapgs+0x13/0x1b
>>  [<ffffffff81104618>] vfs_write+0xae/0x10b
>>  [<ffffffff81104735>] sys_write+0x4a/0x6e
>>  [<ffffffff81009da6>] tracesys+0xd0/0xd5
>> ---[ end trace f7002f0890d5b023 ]---
> 
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