From: William Cohen <wcohen@redhat.com>
To: Pratyush Anand <panand@redhat.com>
Cc: David Long <dave.long@linaro.org>,
systemtap@sourceware.org, Mark Brown <broonie@linaro.org>,
Jeremy Linton <jlinton@redhat.com>,
David Smith <dsmith@redhat.com>,
"Frank Ch. Eigler" <fche@redhat.com>
Subject: Re: exercising current aarch64 kprobe support with systemtap
Date: Thu, 04 Aug 2016 14:50:00 -0000 [thread overview]
Message-ID: <bea9bf10-b59f-b650-6b2a-04305f0aeffa@redhat.com> (raw)
In-Reply-To: <20160804143549.GF22191@localhost.localdomain>
On 08/04/2016 10:35 AM, Pratyush Anand wrote:
> Hi Will,
>
> On 04/08/2016:09:56:45 AM, William Cohen wrote:
>> On 08/04/2016 12:42 AM, Pratyush Anand wrote:
>>> Hi Will,
>>>
>>> On 03/08/2016:01:39:47 PM, William Cohen wrote:
>>>> On 08/03/2016 09:13 AM, Pratyush Anand wrote:
>>>>> On 07/07/2016:03:58:37 PM, Frank Ch. Eigler wrote:
>>>>>> David Long <dave.long@linaro.org> writes:
>>>>>>
>>>>>>> [...]
>>>>>>>> - bug_handler() calls report_bug() which calls __warn()
>>>>>>>> - __warn() does lot of pr_warn() which invokes print_worker_info()
>>>>>>>> where we have a kprobe instrumented.
>>>>>>>> - Therefore, we are encountering this issue.
>>>>>
>>>>> Hi Will,
>>>>>
>>>>> Can you please cross-check if following branch works perfectly with
>>>>> kprobes_onthefly.exp and other systemtap tests.
>>>>>
>>>>> https://github.com/pratyushanand/linux/tree/uprobe/upstream_arm64_devel_v1.1
>>>>>
>>>>> Following patch in above branch should solve this issue.
>>>>> https://github.com/pratyushanand/linux/commit/d0dcc6477f1279ab0bd99aefc30efdecb16c586e
>>>>>
>>>>> However, I am not yet sure that above modification could be the best solution,
>>>>> so discussing at arm kernel list.
>>>>>
>>>>> ~Pratyush
>>>>>
>>>>
>>>> I have an AMD seattle machine set up Fedora24, the upstream_arm64_devel_v1.1 branch kernel locally built, and a locally built checkout of systemtap (systemtap rpm in fc24 doesn't generate models for linux 4.6 and newer kernels). Tried to run the systemtap tests with:
>>>>
>>>> make installcheck RUNTESTFLAGS="--debug systemtap.onthefly/kprobes_onthefly.exp"
>>>>
>>>> However at some point the kernel starts having problems:
>>>>
>>>> http://paste.stg.fedoraproject.org/5375/
>>>
>>> Yes, this is what you were getting with earlier code as well, but now it is not
>>> going to infinite unexpected EL1, so at least proposed kprobe improvement seems
>>> fine to me.
>>>
>>> In this failing test we are getting oom and the oom_killer is called. So,
>>> I think, this is another point of investigation that why this OOM occurs.
>>>
>>> ~Pratyush
>>>
>>
>> Hi,
>>
>> The OOM errors came before the otf_stress_hard_iter_5000 test that previous triggered the infinite unexpected EL1, so can't really say that the proposed patch has fixed the problem.
>
> Yes, yes, previously also we were getting OOM, and then that OOM was triggering
> infinite unexpected EL1, because OOM message uses WARN_ON() to print, and
> WARN_ON() uses "BRK BUG_BRK_IMM". Now when it is printing though BRK, we were
> hitting kprobe at print_worker_info() which was resulting in unexpected EL1.
>
> Proposed patch fixes kprobe tracing within none kprobe BRK context such as
> uprobe or WARN_ON() breakpoint handler etc. So, now a kprobe at
> print_worker_info() will work while printing message of WARN_ON().
>
Okay, I didn't realize that the EL1 issue was hiding the OOM issue. So the patch is helping things.
>
>>
>> Any thoughts on how to track down the oom issue? Are you able to replicate it running the systemtap onthefly/kprobes_onthefly.exp tests?
>
> Sure, will look into. Have reserved a seattle.
Thanks so much.
-Will
next prev parent reply other threads:[~2016-08-04 14:50 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-09 16:17 William Cohen
2016-06-09 19:52 ` William Cohen
2016-06-10 3:42 ` David Long
2016-06-10 5:49 ` David Long
2016-06-10 13:43 ` Pratyush Anand
2016-06-10 14:03 ` William Cohen
2016-06-10 14:37 ` David Long
2016-06-10 15:27 ` William Cohen
2016-06-10 14:20 ` David Long
2016-06-10 15:11 ` William Cohen
2016-06-10 17:07 ` Pratyush Anand
2016-07-12 14:33 ` William Cohen
2016-07-13 18:26 ` David Long
2016-07-13 18:47 ` Pratyush Anand
2016-07-13 19:45 ` William Cohen
2016-06-10 21:28 ` William Cohen
2016-06-10 21:37 ` William Cohen
2016-06-13 4:28 ` Pratyush Anand
2016-06-13 13:42 ` William Cohen
2016-06-22 20:24 ` William Cohen
2016-06-23 3:19 ` David Long
2016-06-23 13:42 ` William Cohen
2016-06-23 13:47 ` David Smith
2016-06-23 15:49 ` William Cohen
2016-06-23 18:26 ` David Long
2016-06-23 19:22 ` William Cohen
2016-06-27 2:57 ` David Long
2016-06-27 14:18 ` Pratyush Anand
2016-06-28 3:20 ` William Cohen
2016-07-04 12:46 ` Pratyush Anand
2016-07-07 19:05 ` David Long
2016-07-07 19:58 ` Frank Ch. Eigler
2016-08-03 13:13 ` Pratyush Anand
2016-08-03 14:51 ` William Cohen
2016-08-03 15:11 ` David Long
2016-08-03 17:40 ` William Cohen
2016-08-03 20:00 ` Lastest kprobes64 patch David Long
2016-08-03 20:01 ` Frank Ch. Eigler
2016-08-03 20:08 ` David Long
2016-08-04 5:03 ` Pratyush Anand
2016-08-04 13:07 ` David Long
2016-08-04 4:42 ` exercising current aarch64 kprobe support with systemtap Pratyush Anand
2016-08-04 13:57 ` William Cohen
2016-08-04 14:36 ` Pratyush Anand
2016-08-04 14:50 ` William Cohen [this message]
2016-08-04 20:51 ` William Cohen
2016-08-17 14:36 ` William Cohen
2016-08-17 18:04 ` David Smith
2016-08-17 18:28 ` William Cohen
2016-08-18 15:07 ` David Smith
2016-08-18 15:16 ` William Cohen
2016-08-18 15:39 ` David Smith
2016-08-18 14:55 ` Pratyush Anand
2016-06-13 16:11 ` William Cohen
2016-06-13 16:15 ` William Cohen
2016-06-14 4:27 ` Pratyush Anand
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