Writing 0 to sysctl value "kernel.sched_time_avg_ms" triggers a lockup:
NMI watchdog: Watchdog detected hard LOCKUP on cpu 4
Modules linked in:
irq event stamp: 81894
hardirqs last enabled at (81893): [<ffffffff8111af88>]
rcu_idle_exit+0x68/0xa0
hardirqs last disabled at (81894): [<ffffffff8113536e>]
tick_nohz_idle_exit+0x2e/0x110
softirqs last enabled at (81870): [<ffffffff810ab8a1>]
_local_bh_enable+0x21/0x50
softirqs last disabled at (81869): [<ffffffff810ace2b>]
irq_enter+0x4b/0x70
CPU: 4 PID: 0 Comm: swapper/4 Not tainted 4.6.0-rc4+ #269
Hardware name: MSI MS-7850/Z87-G41 PC Mate(MS-7850), BIOS V1.3
08/18/2013
0000000000000000 ffff88021fb05b80 ffffffff8141b023 0000000000000000
0000000000000004 ffff88021fb05ba0 ffffffff81163fcf 0000000000000000
ffff88021fb05c40 ffff88021fb05be0 ffffffff8119ae7c 00000001810077ce
Call Trace:
<NMI> [<ffffffff8141b023>] dump_stack+0x85/0xc2
[<ffffffff81163fcf>] watchdog_overflow_callback+0x13f/0x160
[<ffffffff8119ae7c>] __perf_event_overflow+0x9c/0x1f0
[<ffffffff8119baa4>] perf_event_overflow+0x14/0x20
[<ffffffff8100d235>] intel_pmu_handle_irq+0x1d5/0x4a0
[<ffffffff810062ad>] perf_event_nmi_handler+0x2d/0x50
[<ffffffff81174397>] ? tracing_generic_entry_update+0x97/0xb0
[<ffffffff81039cef>] nmi_handle+0xbf/0x2f0
[<ffffffff81039c35>] ? nmi_handle+0x5/0x2f0
[<ffffffff81174397>] ? tracing_generic_entry_update+0x97/0xb0
[<ffffffff8103a171>] default_do_nmi+0x71/0x1b0
[<ffffffff8103a3c5>] do_nmi+0x115/0x170
[<ffffffff8194b511>] end_repeat_nmi+0x1a/0x1e
[<ffffffff81174397>] ? tracing_generic_entry_update+0x97/0xb0
[<ffffffff81174397>] ? tracing_generic_entry_update+0x97/0xb0
[<ffffffff81174397>] ? tracing_generic_entry_update+0x97/0xb0
<<EOE>> [<ffffffff81177d3f>] ? trace_buffer_lock_reserve+0x3f/0x60
[<ffffffff810d3d51>] ? sched_avg_update+0x51/0xc0
[<ffffffff811781e5>] __trace_bputs+0x75/0x100
[<ffffffff810d3d79>] sched_avg_update+0x79/0xc0
[<ffffffff810dedc3>] cpu_load_update+0xa3/0xd0
[<ffffffff810e694a>] cpu_load_update_nohz_stop+0x7a/0x80
[<ffffffff811353b7>] tick_nohz_idle_exit+0x77/0x110
[<ffffffff810f0866>] cpu_startup_entry+0x176/0x420
[<ffffffff810589f4>] start_secondary+0x104/0x110
This is due to the loop in sched_avg_update() that fails to make any
progress when the update delay is 0.
Since this is non-sense to set that value to 0 anyway, force a minimum
of at least 1 millisecond.
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/sysctl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 87b2fc3..b730dd6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -345,7 +345,8 @@ static struct ctl_table kern_table[] = {
.data = &sysctl_sched_time_avg,
.maxlen = sizeof(unsigned int),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "sched_shares_window_ns",
--
2.7.0
