linux-kernel - Re: [paulmck-rcu:dev.2025.08.13a] [tracing] 364ac25d46: WARNING:at_arch/x86/mm/fault.c:#do_user_addr

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Message-ID: <aLebLoM2OQD+KPxQ@xsang-OptiPlex-9020>
Date: Wed, 3 Sep 2025 09:34:38 +0800
From: Oliver Sang <oliver.sang@...el.com>
To: "Paul E. McKenney" <paulmck@...nel.org>
CC: <oe-lkp@...ts.linux.dev>, <lkp@...el.com>, <linux-kernel@...r.kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Steven Rostedt
	<rostedt@...dmis.org>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	<linux-trace-kernel@...r.kernel.org>, <oliver.sang@...el.com>
Subject: Re: [paulmck-rcu:dev.2025.08.13a] [tracing]  364ac25d46:
 WARNING:at_arch/x86/mm/fault.c:#do_user_addr_fault

hi, Paul,

On Fri, Aug 29, 2025 at 08:07:41AM -0700, Paul E. McKenney wrote:
> On Thu, Aug 21, 2025 at 01:26:45PM +0800, kernel test robot wrote:
> > 
> > hi, Paul,
> > 
> > we also noticed there is similar commit in newer branch
> >   dev.2025.08.14a
> >   dev.2025.08.19a
> > but we didn't finish any bisect for them so far.
> > 
> > if the issue is already known and fixed in newer version, please just ignore
> > this report. sorry if any inconvenience.
> > 
> > below full report FYI.
> > 
> > 
> > Hello,
> > 
> > kernel test robot noticed "WARNING:at_arch/x86/mm/fault.c:#do_user_addr_fault" on:
> > 
> > commit: 364ac25d46eea504eb90229d2a1f92e18c1a1eae ("tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast")
> > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2025.08.13a
> > 
> > in testcase: boot
> > 
> > config: i386-randconfig-004-20250819
> > compiler: clang-20
> > test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 4G
> > 
> > (please refer to attached dmesg/kmsg for entire log/backtrace)
> 
> Thank you for your testing efforts, and apologies for being slow!
> 
> Could you please try the diagnostic patch at the end of this email?
> 
> 							Thanx, Paul

by applying the patch, the issue gone. but since you said this is a 'diagnostic
patch', not sure if it's a real fix. anyway:

Tested-by: kernel test robot <oliver.sang@...el.com>


[...]

> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <oliver.sang@...el.com>
> > | Closes: https://lore.kernel.org/oe-lkp/202508211038.c93e8603-lkp@intel.com

[...]

> > The kernel config and materials to reproduce are available at:
> > https://download.01.org/0day-ci/archive/20250821/202508211038.c93e8603-lkp@intel.com
> > -- 
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests/wiki
> 
> 
> commit 2d6142ce44dca77fb173bb96850634b169277214
> Author: Paul E. McKenney <paulmck@...nel.org>
> Date:   Thu Aug 28 12:56:42 2025 -0700
> 
>     EXP tracing: Diagnostic for __DECLARE_TRACE() use of SRCU-fast
>     
>     This patch is intended to test the theory that preemption needs to be
>     disabled in some portion of the tracing infrastructure extending from
>     the __DECLARE_TRACE() macro to the target BPF program.
>     
>     Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> 
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index a22c1ab88560b8..c422e4c5ed51ed 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -273,7 +273,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
>  	static inline void __do_trace_##name(proto)			\
>  	{								\
>  		if (cond) {						\
> -			guard(srcu_fast_notrace)(&tracepoint_srcu);	\
> +			guard(preempt_notrace)();			\
>  			__DO_TRACE_CALL(name, TP_ARGS(args));		\
>  		}							\
>  	}								\