Re: WARN_ON_ONCE() hit at kernel/events/core.c:330

Thomas-Mich Richter
2019-04-03T11:26:52Z

On 4/3/19 12:41 PM, Peter Zijlstra wrote:
> On Wed, Apr 03, 2019 at 11:47:00AM +0200, Thomas-Mich Richter wrote:
>> I use linux 5.1.0-rc3 on s390 and got this WARN_ON_ONCE message:
>>
>> WARNING: CPU: 15 PID: 0 at kernel/events/core.c:330
>> event_function_local.constprop.79+0xe2/0xe8
>>
>> which was introduced with
>> commit cca2094605ef ("perf/core: Fix event_function_local()").
>>
>> This is the WARN_ON_ONCE message, which sometimes shows up in the kernel
>> log:
>> [ 4598.316519] WARNING: CPU: 15 PID: 0 at kernel/events/core.c:330
>> event_function_local.constprop.79+0xe2/0xe8
>> [ 4598.316524] Kernel panic - not syncing: panic_on_warn set ...
>> [ 4598.316527] CPU: 15 PID: 0 Comm: swapper/15 Tainted: G OE
>> 5.1.0-20190402.rc3.git0.5e7a8ca31926.300.fc29.s390x+git #1
>> [ 4598.316529] Hardware name: IBM 2964 NC9 712 (LPAR)
>> [ 4598.316531] Call Trace:
>> [ 4598.316534] ([<0000000000112eb8>] show_stack+0x58/0x70)
>> [ 4598.316538] [<0000000000a820aa>] dump_stack+0x7a/0xa8
>> [ 4598.316541] [<0000000000143b52>] panic+0x11a/0x2d0
>> [ 4598.316543] [<00000000001439b0>] __warn+0xf8/0x118
>> [ 4598.316545] [<0000000000a811a8>] report_bug+0xd8/0x150
>> [ 4598.316547] [<00000000001014ac>] do_report_trap+0xc4/0xe0
>> [ 4598.316549] [<0000000000101680>] illegal_op+0x138/0x150
>> [ 4598.316552] [<0000000000aa233c>] pgm_check_handler+0x1cc/0x220
>> [ 4598.316554] [<00000000002a6d02>] event_function_local.constprop.79+
>> 0xe2/0xe8
>> [ 4598.316556] ([<00000000002a6c7a>] event_function_local.constprop.79+
>> 0x5a/0xe8)
>> [ 4598.316559] [<00000000002aa400>] perf_pending_event+0x88/0xb0
>> [ 4598.316561] [<0000000000271a8c>] irq_work_run_list+0x8c/0xb8
>> [ 4598.316563] [<0000000000271d78>] irq_work_tick+0x48/0x68
>> [ 4598.316566] [<00000000001d6058>] update_process_times+0x68/0x80
>> [ 4598.316568] [<00000000001e6c10>] tick_sched_handle.isra.6+0x50/0x60
>> [ 4598.316570] [<00000000001e6c7e>] tick_sched_timer+0x5e/0xb8
>> [ 4598.316573] [<00000000001d6b6a>] __hrtimer_run_queues+0x10a/0x2c0
>> [ 4598.316575] [<00000000001d7a88>] hrtimer_interrupt+0x138/0x2a8
>> [ 4598.316577] [<000000000010c3e4>] do_IRQ+0xac/0xb0
>> [ 4598.316597] [<0000000000aa2744>] ext_int_handler+0x128/0x12c
>> [ 4598.316600] [<00000000001034f6>] enabled_wait+0x46/0xd0
>> [ 4598.316602] ([<000003e000d2fe10>] 0x3e000d2fe10)
>> [ 4598.316604] [<0000000000103842>] arch_cpu_idle+0x3a/0x50
>> [ 4598.316606] [<000000000017b808>] do_idle+0x180/0x1b0
>> [ 4598.316608] [<000000000017ba06>] cpu_startup_entry+0x36/0x40
>> [ 4598.316611] [<0000000000115d16>] smp_init_secondary+0xd6/0xf0
>> [ 4598.316613] [<000000000011521e>] smp_start_secondary+0x86/0x98
>>
>> Any ideas or hints who to avoid/fix this warning?
>
> Some thoughts here:
>
> https://lkml.kernel.org/r/20190213101644.GN32534@hirez.programming.kicks-ass.net
>
> tl;dr, I've no frigging clue.
>
>> I ran a user space program which uses
>>
>> 1. perf_event_open() system call with type HARDWARE
>> and PERF_COUNT_HW_CPU_CYCLES in sampling mode.
>> 2. Assigns signal SIGIO to the file descriptor returned from
>> perf_event_open() using:
>> rc = fcntl(fd, F_SETFL, O_RDWR | O_NONBLOCK | O_ASYNC);
>> rc |= fcntl(fd, F_SETSIG, signo);
>> rc |= fcntl(fd, F_SETOWN, getpid());
>>
>> 3. The signal handler increments some variables and issues
>> ioctl(fd, PERF_EVENT_IOC_REFRESH, 1);
>> to restart signal delivery.
>>
>> I can send you the test program if needed.
>
> Does it reproduce on x86 without virt on? I don't have a PPC LPAR to
> test things on.
>

It happens on an s390 mainframe (not PowerPC) without KVM or z/VM virtualisation.
I'll try to repro it on x86.

PS: Put my team members Heiko and Hendrik on cc.
--
Thomas Richter, Dept 3252, IBM s390 Linux Development, Boeblingen, Germany
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