From: Prarit Bhargava <prarit@redhat.com>
To: Jason Baron <jbaron@akamai.com>
Cc: Andi Kleen <ak@linux.intel.com>, Jonathan Corbet <corbet@lwn.net>,
kexec@lists.infradead.org, Rusty Russell <rusty@rustcorp.com.au>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
Fabian Frederick <fabf@skynet.be>,
isimatu.yasuaki@jp.fujitsu.com, "H. Peter Anvin" <hpa@zytor.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-api@vger.kernel.org, vgoyal@redhat.com
Subject: Re: [PATCH V4] kernel, add bug_on_warn
Date: Mon, 27 Oct 2014 14:15:20 -0400 [thread overview]
Message-ID: <544E8BB8.8000707@redhat.com> (raw)
In-Reply-To: <544E8985.50203@akamai.com>
On 10/27/2014 02:05 PM, Jason Baron wrote:
> Hi Prarit,
>
> On 10/24/2014 08:53 AM, Prarit Bhargava wrote:
>> There have been several times where I have had to rebuild a kernel to
>> cause a panic when hitting a WARN() in the code in order to get a crash
>> dump from a system. Sometimes this is easy to do, other times (such as
>> in the case of a remote admin) it is not trivial to send new images to the
>> user.panic_on_stackoverflow
>>
>> A much easier method would be a switch to change the WARN() over to a
>> BUG(). This makes debugging easier in that I can now test the actual
>> image the WARN() was seen on and I do not have to engage in remote
>> debugging.
>>
>> This patch adds a bug_on_warn kernel parameter and
>> /proc/sys/kernel/bug_on_warn calls BUG() in the warn_slowpath_common()
>> path. The function will still print out the location of the warning.
>>
>> An example of the bug_on_warn output:
>>
>> The first line below is from the WARN_ON() to output the WARN_ON()'s location.
>> After that the new BUG() call is displayed.
>>
>> WARNING: CPU: 27 PID: 3204 at
>> /home/rhel7/redhat/debug/dummy-module/dummy-module.c:25 init_dummy+0x28/0x30
>> [dummy_module]()
>> bug_on_warn set, calling BUG()...
>> ------------[ cut here ]------------
>> kernel BUG at kernel/panic.c:434!
>
> Seems reasonable-I'm wondering why you just don't call panic() in this
> case. The BUG() call at line '434' doesn't at anything since its just being
> called from panic.c.
Hmm ... I didn't even think about that.
>
> So something like 'panic_on_warn' would seem to be more appropriate
> in keeping with things like 'panic_on_oops' or 'panic_on_stackoverflow'.
I like it a lot better that way too :) I'm changing it to panic_on_warn unless
anyone has any strenuous objections.
P.
>
> Thanks,
>
> -Jason
>
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WARNING: multiple messages have this Message-ID (diff)
From: Prarit Bhargava <prarit-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Jason Baron <jbaron-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org>
Cc: Andi Kleen <ak-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>,
kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>,
linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Fabian Frederick <fabf-AgBVmzD5pcezQB+pC5nmwQ@public.gmane.org>,
isimatu.yasuaki-+CUm20s59erQFUHtdCDX3A@public.gmane.org,
"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
Masami Hiramatsu
<masami.hiramatsu.pt-FCd8Q96Dh0JBDgjK7y7TUQ@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org
Subject: Re: [PATCH V4] kernel, add bug_on_warn
Date: Mon, 27 Oct 2014 14:15:20 -0400 [thread overview]
Message-ID: <544E8BB8.8000707@redhat.com> (raw)
In-Reply-To: <544E8985.50203-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org>
On 10/27/2014 02:05 PM, Jason Baron wrote:
> Hi Prarit,
>
> On 10/24/2014 08:53 AM, Prarit Bhargava wrote:
>> There have been several times where I have had to rebuild a kernel to
>> cause a panic when hitting a WARN() in the code in order to get a crash
>> dump from a system. Sometimes this is easy to do, other times (such as
>> in the case of a remote admin) it is not trivial to send new images to the
>> user.panic_on_stackoverflow
>>
>> A much easier method would be a switch to change the WARN() over to a
>> BUG(). This makes debugging easier in that I can now test the actual
>> image the WARN() was seen on and I do not have to engage in remote
>> debugging.
>>
>> This patch adds a bug_on_warn kernel parameter and
>> /proc/sys/kernel/bug_on_warn calls BUG() in the warn_slowpath_common()
>> path. The function will still print out the location of the warning.
>>
>> An example of the bug_on_warn output:
>>
>> The first line below is from the WARN_ON() to output the WARN_ON()'s location.
>> After that the new BUG() call is displayed.
>>
>> WARNING: CPU: 27 PID: 3204 at
>> /home/rhel7/redhat/debug/dummy-module/dummy-module.c:25 init_dummy+0x28/0x30
>> [dummy_module]()
>> bug_on_warn set, calling BUG()...
>> ------------[ cut here ]------------
>> kernel BUG at kernel/panic.c:434!
>
> Seems reasonable-I'm wondering why you just don't call panic() in this
> case. The BUG() call at line '434' doesn't at anything since its just being
> called from panic.c.
Hmm ... I didn't even think about that.
>
> So something like 'panic_on_warn' would seem to be more appropriate
> in keeping with things like 'panic_on_oops' or 'panic_on_stackoverflow'.
I like it a lot better that way too :) I'm changing it to panic_on_warn unless
anyone has any strenuous objections.
P.
>
> Thanks,
>
> -Jason
>
WARNING: multiple messages have this Message-ID (diff)
From: Prarit Bhargava <prarit@redhat.com>
To: Jason Baron <jbaron@akamai.com>
Cc: linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Rusty Russell <rusty@rustcorp.com.au>,
"H. Peter Anvin" <hpa@zytor.com>, Andi Kleen <ak@linux.intel.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Fabian Frederick <fabf@skynet.be>,
vgoyal@redhat.com, isimatu.yasuaki@jp.fujitsu.com,
linux-doc@vger.kernel.org, kexec@lists.infradead.org,
linux-api@vger.kernel.org
Subject: Re: [PATCH V4] kernel, add bug_on_warn
Date: Mon, 27 Oct 2014 14:15:20 -0400 [thread overview]
Message-ID: <544E8BB8.8000707@redhat.com> (raw)
In-Reply-To: <544E8985.50203@akamai.com>
On 10/27/2014 02:05 PM, Jason Baron wrote:
> Hi Prarit,
>
> On 10/24/2014 08:53 AM, Prarit Bhargava wrote:
>> There have been several times where I have had to rebuild a kernel to
>> cause a panic when hitting a WARN() in the code in order to get a crash
>> dump from a system. Sometimes this is easy to do, other times (such as
>> in the case of a remote admin) it is not trivial to send new images to the
>> user.panic_on_stackoverflow
>>
>> A much easier method would be a switch to change the WARN() over to a
>> BUG(). This makes debugging easier in that I can now test the actual
>> image the WARN() was seen on and I do not have to engage in remote
>> debugging.
>>
>> This patch adds a bug_on_warn kernel parameter and
>> /proc/sys/kernel/bug_on_warn calls BUG() in the warn_slowpath_common()
>> path. The function will still print out the location of the warning.
>>
>> An example of the bug_on_warn output:
>>
>> The first line below is from the WARN_ON() to output the WARN_ON()'s location.
>> After that the new BUG() call is displayed.
>>
>> WARNING: CPU: 27 PID: 3204 at
>> /home/rhel7/redhat/debug/dummy-module/dummy-module.c:25 init_dummy+0x28/0x30
>> [dummy_module]()
>> bug_on_warn set, calling BUG()...
>> ------------[ cut here ]------------
>> kernel BUG at kernel/panic.c:434!
>
> Seems reasonable-I'm wondering why you just don't call panic() in this
> case. The BUG() call at line '434' doesn't at anything since its just being
> called from panic.c.
Hmm ... I didn't even think about that.
>
> So something like 'panic_on_warn' would seem to be more appropriate
> in keeping with things like 'panic_on_oops' or 'panic_on_stackoverflow'.
I like it a lot better that way too :) I'm changing it to panic_on_warn unless
anyone has any strenuous objections.
P.
>
> Thanks,
>
> -Jason
>
next prev parent reply other threads:[~2014-10-27 18:15 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-24 12:53 [PATCH V4] kernel, add bug_on_warn Prarit Bhargava
2014-10-24 12:53 ` Prarit Bhargava
2014-10-27 18:05 ` Jason Baron
2014-10-27 18:05 ` Jason Baron
2014-10-27 18:05 ` Jason Baron
2014-10-27 18:15 ` Prarit Bhargava [this message]
2014-10-27 18:15 ` Prarit Bhargava
2014-10-27 18:15 ` Prarit Bhargava
2014-10-28 2:32 ` Dave Young
2014-10-28 2:32 ` Dave Young
2014-10-28 5:41 ` Masami Hiramatsu
2014-10-28 5:41 ` Masami Hiramatsu
2014-10-28 0:00 ` Yasuaki Ishimatsu
2014-10-28 0:00 ` Yasuaki Ishimatsu
2014-10-28 0:00 ` Yasuaki Ishimatsu
2014-10-28 12:16 ` Andi Kleen
2014-10-28 12:16 ` Andi Kleen
2014-10-28 12:22 ` Prarit Bhargava
2014-10-28 12:22 ` Prarit Bhargava
2014-10-28 12:22 ` Prarit Bhargava
2014-10-28 12:29 ` Vivek Goyal
2014-10-28 12:29 ` Vivek Goyal
2014-10-28 12:44 ` Andi Kleen
2014-10-28 12:44 ` Andi Kleen
2014-10-28 12:48 ` Prarit Bhargava
2014-10-28 12:48 ` Prarit Bhargava
2014-10-28 12:48 ` Prarit Bhargava
2014-10-28 12:56 ` Andi Kleen
2014-10-28 12:56 ` Andi Kleen
2014-10-28 12:56 ` Andi Kleen
2014-10-28 13:19 ` Prarit Bhargava
2014-10-28 13:19 ` Prarit Bhargava
2014-10-28 13:19 ` Prarit Bhargava
2014-10-28 12:55 ` Vivek Goyal
2014-10-28 12:55 ` Vivek Goyal
2014-10-28 12:59 ` Andi Kleen
2014-10-28 12:59 ` Andi Kleen
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