From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: tracing: BUG: sleeping function called from invalid context Date: Fri, 9 May 2014 11:37:00 +0200 Message-ID: <20140509093700.GA29014@linutronix.de> References: <53518CD8.4020706@meduna.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: "linux-rt-users@vger.kernel.org" To: Stanislav Meduna , rostedt@goodmis.org Return-path: Received: from www.linutronix.de ([62.245.132.108]:33617 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752652AbaEIJhF (ORCPT ); Fri, 9 May 2014 05:37:05 -0400 Content-Disposition: inline In-Reply-To: <53518CD8.4020706@meduna.org> Sender: linux-rt-users-owner@vger.kernel.org List-ID: * 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: [] vfs_write+0x1cc/0x1d0 > #1: (trace_types_lock){......}, at: [] tracing_set_tracer+0x1c/0x2ac > #2: (&buffer->mutex#2){......}, at: [] ring_buffer_resize+0xac/0x3dc >Preemption disabled at:[< (null)>] (null) > >CPU: 0 PID: 607 Comm: bash Not tainted 3.12.15-rt25+ #124 >[] (rt_spin_lock+0x28/0x68) from [] (free_hot_cold_page+0x84/0x3b8) >[] (free_hot_cold_page+0x84/0x3b8) from [] (free_buffer_page+0x14/0x20) >[] (free_buffer_page+0x14/0x20) from [] (rb_update_pages+0x280/0x338) >[] (rb_update_pages+0x280/0x338) from [] (ring_buffer_resize+0x32c/0x3dc) >[] (ring_buffer_resize+0x32c/0x3dc) from [] (free_snapshot+0x18/0x38) >[] (free_snapshot+0x18/0x38) from [] (tracing_set_tracer+0x27c/0x2ac) >[] (tracing_set_tracer+0x27c/0x2ac) from [] (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