Re: [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context

From: Andy Lutomirski <luto@amacapital.net>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: "Borislav Petkov" <bp@alien8.de>, "X86 ML" <x86@kernel.org>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Oleg Nesterov" <oleg@redhat.com>,
	"Tony Luck" <tony.luck@intel.com>,
	"Andi Kleen" <andi@firstfloor.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	"Josh Triplett" <josh@joshtriplett.org>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>
Subject: Re: [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context
Date: Fri, 23 Jan 2015 17:25:45 -0800	[thread overview]
Message-ID: <CALCETrXtA-xbec2oGBXW6KUFMY8v=MN2gS5trn1J221OSDDuJA@mail.gmail.com> (raw)
In-Reply-To: <54C2B396.9090106@oracle.com>

On Fri, Jan 23, 2015 at 12:48 PM, Sasha Levin <sasha.levin@oracle.com> wrote:
> On 01/23/2015 01:34 PM, Andy Lutomirski wrote:
>> On Fri, Jan 23, 2015 at 10:04 AM, Borislav Petkov <bp@alien8.de> wrote:
>>> On Fri, Jan 23, 2015 at 09:58:01AM -0800, Andy Lutomirski wrote:
>>>>> [  543.999079] Call Trace:
>>>>> [  543.999079] dump_stack (lib/dump_stack.c:52)
>>>>> [  543.999079] lockdep_rcu_suspicious (kernel/locking/lockdep.c:4259)
>>>>> [  543.999079] atomic_notifier_call_chain (include/linux/rcupdate.h:892 kernel/notifier.c:182 kernel/notifier.c:193)
>>>>> [  543.999079] ? atomic_notifier_call_chain (kernel/notifier.c:192)
>>>>> [  543.999079] notify_die (kernel/notifier.c:538)
>>>>> [  543.999079] ? atomic_notifier_call_chain (kernel/notifier.c:538)
>>>>> [  543.999079] ? debug_smp_processor_id (lib/smp_processor_id.c:57)
>>>>> [  543.999079] do_debug (arch/x86/kernel/traps.c:652)
>>>>> [  543.999079] ? trace_hardirqs_on (kernel/locking/lockdep.c:2609)
>>>>> [  543.999079] ? do_int3 (arch/x86/kernel/traps.c:610)
>>>>> [  543.999079] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2554 kernel/locking/lockdep.c:2601)
>>>>> [  543.999079] debug (arch/x86/kernel/entry_64.S:1310)
>>>>
>>>> I don't know how to read this stack trace.  Are we in do_int3,
>>>> do_debug, or both?  I didn't change do_debug at all.
>>>
>>> It looks like we're in do_debug. do_int3 is only on the stack but not
>>> part of the current frame if I can trust the '?' ...
>>>
>>
>> It's possible that an int3 happened and I did something wrong on
>> return that caused a subsequent do_debug to screw up, but I don't see
>> how my patch would have caused that.
>>
>> Were there any earlier log messages?
>
> Nope, nothing odd before or after.

Trinity just survived for a decent amount of time for me with my
patches, other than a bunch of apparently expected OOM kills.  I have
no idea how to tell trinity how much memory to use.

--Andy