Re: tracing: BUG: sleeping function called from invalid context
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2014-05-09 09:37:05
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
* Stanislav Meduna | 2014-04-18 22:36:40 [+0200]:
Hi,
Hi,
BUG: sleeping function called from invalid context at /home/stano/Kernels/linux-3.12-rt/kernel/rtmutex.c:673
in_atomic(): 1, irqs_disabled(): 0, pid: 607, name: bash
3 locks held by bash/607:
#0: (sb_writers#8){......}, at: [<c00de6f4>] vfs_write+0x1cc/0x1d0
#1: (trace_types_lock){......}, at: [<c0087764>] tracing_set_tracer+0x1c/0x2ac
#2: (&buffer->mutex#2){......}, at: [<c0080220>] ring_buffer_resize+0xac/0x3dc
Preemption disabled at:[< (null)>] (null)
CPU: 0 PID: 607 Comm: bash Not tainted 3.12.15-rt25+ #124
[<c02f7010>] (rt_spin_lock+0x28/0x68) from [<c00aa468>] (free_hot_cold_page+0x84/0x3b8)
[<c00aa468>] (free_hot_cold_page+0x84/0x3b8) from [<c007cb2c>] (free_buffer_page+0x14/0x20)
[<c007cb2c>] (free_buffer_page+0x14/0x20) from [<c00800bc>] (rb_update_pages+0x280/0x338)
[<c00800bc>] (rb_update_pages+0x280/0x338) from [<c00804a0>] (ring_buffer_resize+0x32c/0x3dc)
[<c00804a0>] (ring_buffer_resize+0x32c/0x3dc) from [<c0087530>] (free_snapshot+0x18/0x38)
[<c0087530>] (free_snapshot+0x18/0x38) from [<c00879c4>] (tracing_set_tracer+0x27c/0x2ac)
[<c00879c4>] (tracing_set_tracer+0x27c/0x2ac) from [<c0087a4c>] (tracing_set_trace_write+0x58/0x114)Can be triggered by: | cd /sys/kernel/debug/tracing/ | echo 1 > events/enable | sleep 2 # fill the buffer | echo 1024 > buffer_size_kb # shrink the buffer the shrinking of the buffer does this. Steven, are you comfortable with this change:
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index fc4da2d..112d4a5 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c@@ -1682,28 +1682,22 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, * We can't schedule on offline CPUs, but it's not necessary * since we can change their buffer sizes without any race. */ + migrate_disable(); for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; if (!cpu_buffer->nr_pages_to_update) continue; /* The update must run on the CPU that is being updated. */ - preempt_disable(); if (cpu == smp_processor_id() || !cpu_online(cpu)) { rb_update_pages(cpu_buffer); cpu_buffer->nr_pages_to_update = 0; } else { - /* - * Can not disable preemption for schedule_work_on() - * on PREEMPT_RT. - */ - preempt_enable(); schedule_work_on(cpu, &cpu_buffer->update_pages_work); - preempt_disable(); } - preempt_enable(); } + migrate_enable(); /* wait for all the updates to complete */ for_each_buffer_cpu(buffer, cpu) {
@@ -1740,22 +1734,16 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, get_online_cpus(); - preempt_disable(); + migrate_disable(); /* The update must run on the CPU that is being updated. */ if (cpu_id == smp_processor_id() || !cpu_online(cpu_id)) rb_update_pages(cpu_buffer); else { - /* - * Can not disable preemption for schedule_work_on() - * on PREEMPT_RT. - */ - preempt_enable(); schedule_work_on(cpu_id, &cpu_buffer->update_pages_work); wait_for_completion(&cpu_buffer->update_done); - preempt_disable(); } - preempt_enable(); + migrate_enable(); cpu_buffer->nr_pages_to_update = 0; put_online_cpus();
--
2.0.0.rc0
>Thanks
Sebastian