Re: [sched] WARNING: CPU: 0 PID: 3166 at kernel/cpu.c:84put_online_cpus()

From: Fengguang Wu
Date: Tue Oct 22 2013 - 17:25:12 EST

On Tue, Oct 22, 2013 at 10:46:32PM +0200, Peter Zijlstra wrote:
> On Sat, Oct 19, 2013 at 08:51:29AM +0800, Fengguang Wu wrote:
> > Greetings,
> > [ 58.695502] ------------[ cut here ]------------
> > [ 58.697835] WARNING: CPU: 0 PID: 3166 at kernel/cpu.c:84 put_online_cpus+0x43/0x70()
> > [ 58.702423] Modules linked in:
> > [ 58.704404] CPU: 0 PID: 3166 Comm: trinity-child0 Not tainted 3.12.0-rc5-01882-gf3db366 #1172
> > [ 58.708530] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > [ 58.710992] 0000000000000000 ffff88000acfbe50 ffffffff81a24643 0000000000000000
> > [ 58.715410] ffff88000acfbe88 ffffffff810c3e6b ffffffff810c3fef 0000000000000000
> > [ 58.719826] 0000000000000000 0000000000006ee0 0000000000000ffc ffff88000acfbe98
> > [ 58.724348] Call Trace:
> > [ 58.726190] [<ffffffff81a24643>] dump_stack+0x4d/0x66
> > [ 58.728531] [<ffffffff810c3e6b>] warn_slowpath_common+0x7f/0x98
> > [ 58.731069] [<ffffffff810c3fef>] ? put_online_cpus+0x43/0x70
> > [ 58.733664] [<ffffffff810c3f32>] warn_slowpath_null+0x1a/0x1c
> > [ 58.736258] [<ffffffff810c3fef>] put_online_cpus+0x43/0x70
> > [ 58.738686] [<ffffffff810efd59>] sched_setaffinity+0x7d/0x1f9
> > [ 58.741210] [<ffffffff810efce1>] ? sched_setaffinity+0x5/0x1f9
> > [ 58.743775] [<ffffffff81a2f724>] ? _raw_spin_unlock_irq+0x2c/0x3e
> > [ 58.746417] [<ffffffff810c7012>] ? do_setitimer+0x194/0x1f5
> > [ 58.748899] [<ffffffff810eff37>] SyS_sched_setaffinity+0x62/0x71
> > [ 58.751481] [<ffffffff81a373a9>] system_call_fastpath+0x16/0x1b
> > [ 58.754070] ---[ end trace 034818a1f6f06868 ]---
> > [ 58.757521] ------------[ cut here ]------------
>
> Duh.. must've been blind or so..
>
> Does this make it go away

> @@ -3716,7 +3716,6 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
> p = find_process_by_pid(pid);
> if (!p) {
> rcu_read_unlock();
> - put_online_cpus();
> return -ESRCH;

Yes, it fixed the WARNING.

Tested-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>

// The tests was queued for Michael Wang and have just finished.

There seems show up a new unreliable error "BUG:kernel_test_crashed".
I'll increase test runs to confirm whether it's a new bug.

/kernel/x86_64-lkp/686c61a262ef88fdbc81c4d18bd0fcfc904d3f3e
+----------------------------------------------------------------------------------+-----------+--------------+--------------+
| | v3.12-rc4 | 6acce3ef8452 | 686c61a262ef |
+----------------------------------------------------------------------------------+-----------+--------------+--------------+
| good_boots | 539 | 0 | 16 |
| has_kernel_error_warning | 24 | 20 | 1 |
| INFO:task_blocked_for_more_than_seconds | 14 | | |
| WARNING:CPU:PID:at_arch/x86/kernel/cpu/perf_event_intel.c:intel_pmu_handle_irq() | 1 | | |
| INFO:NMI_handler(perf_event_nmi_handler)took_too_long_to_run:msecs | 1 | | |
| XFS(vde):xlog_verify_grant_tail:space_BBTOB(tail_blocks) | 5 | | |
| Corruption_detected.Unmount_and_run_xfs_repair | 5 | | |
| metadata_I/O_error:block(xfs_trans_read_buf_map)error_numblks | 5 | | |
| BUG:kernel_test_hang | 3 | | |
| WARNING:CPU:PID:at_kernel/cpu.c:put_online_cpus() | 0 | 20 | |
| BUG:kernel_test_crashed | 0 | 0 | 1 |
+----------------------------------------------------------------------------------+-----------+--------------+--------------+

/kernel/x86_64-lkp-CONFIG_SCHED_DEBUG/686c61a262ef88fdbc81c4d18bd0fcfc904d3f3e

+------------------------------------------------------------------------------------+-----------+--------------+--------------+
| | v3.12-rc4 | 6acce3ef8452 | 686c61a262ef |
+------------------------------------------------------------------------------------+-----------+--------------+--------------+
| good_boots | 39 | 0 | 16 |
| has_kernel_error_warning | 0 | 20 | |
| INFO:rcu_sched_self-detected_stall_on_CPU(t=jiffies_g=c=q=) | 0 | 1 | |
| INFO:task_blocked_for_more_than_seconds | 0 | 6 | |
| INFO:NMI_handler(arch_trigger_all_cpu_backtrace_handler)took_too_long_to_run:msecs | 0 | 3 | |
| Kernel_panic-not_syncing:hung_task:blocked_tasks | 0 | 3 | |
| WARNING:CPU:PID:at_kernel/cpu.c:put_online_cpus() | 0 | 12 | |
| BUG:kernel_test_crashed | 0 | 1 | |
+------------------------------------------------------------------------------------+-----------+--------------+--------------+

/kernel/x86_64-lkp-CONFIG_SCSI_DEBUG/686c61a262ef88fdbc81c4d18bd0fcfc904d3f3e

+------------------------------------------------------------------+-----------+--------------+--------------+
| | v3.12-rc4 | 6acce3ef8452 | 686c61a262ef |
+------------------------------------------------------------------+-----------+--------------+--------------+
| good_boots | 38 | 1 | 17 |
| has_kernel_error_warning | 1 | 20 | 1 |
| Out_of_memory:Kill_process | 1 | | |
| Kernel_panic-not_syncing:Out_of_memory_and_no_killable_processes | 1 | | |
| BUG:kernel_test_oops | 1 | | |
| WARNING:CPU:PID:at_kernel/cpu.c:put_online_cpus() | 0 | 20 | |
| INFO:rcu_sched_self-detected_stall_on_CPU(t=jiffies_g=c=q=) | 0 | 0 | 1 |
+------------------------------------------------------------------+-----------+--------------+--------------+

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