Bug 4406

Summary:	Yocto-linux-rt: BUG() warning is triggered in rt kernel when run 'perf top' command on ARM/PowerPC
Product:	[Runtime] General Runtime	Reporter:	Xufeng Zhang <xufeng.zhang>
Component:	General Runtime	Assignee:	Xufeng Zhang <xufeng.zhang>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	Medium	CC:	dvhart
Version:	unspecified
Target Milestone:	1.5 M2
Hardware:	x86
OS:	Multiple
Whiteboard:
OS type for building Yocto:	---	Type of Regression:	---
Verified:		Documentation change:	No (bug/feature does not impact docs)

Description Xufeng Zhang 2013-04-24 07:34:47 UTC

This problem is detected on ARM and PowerPC platforms when run "perf top" command
after CONFIG_DEBUG_ATOMIC_SLEEP is enabled in rt kernel.

Call Trace on ARM:
BUG: sleeping function called from invalid context at linux/kernel/rtmutex.c:658
in_atomic(): 1, irqs_disabled(): 128, pid: 1731, name: perf
[<80017d6c>] (unwind_backtrace+0x0/0x104) from [<806416c4>] (dump_stack+0x20/0x24)
[<806416c4>] (dump_stack+0x20/0x24) from [<80061208>] (__might_sleep+0xf4/0x108)
[<80061208>] (__might_sleep+0xf4/0x108) from [<8064a74c>] (rt_spin_lock+0x2c/0x38)
[<8064a74c>] (rt_spin_lock+0x2c/0x38) from [<800642e8>] (__wake_up+0x34/0x60)
[<800642e8>] (__wake_up+0x34/0x60) from [<800e2610>] (perf_event_wakeup+0x40/0x84)
[<800e2610>] (perf_event_wakeup+0x40/0x84) from [<800e2690>] (perf_pending_event+0x3c/0x60)
[<800e2690>] (perf_pending_event+0x3c/0x60) from [<800dd36c>] (irq_work_run+0x74/0xa4)
[<800dd36c>] (irq_work_run+0x74/0xa4) from [<8001b018>] (armv7pmu_handle_irq+0x12c/0x19c)
[<8001b018>] (armv7pmu_handle_irq+0x12c/0x19c) from [<800a87b0>] (handle_irq_event_percpu+0xf0/0x438)
[<800a87b0>] (handle_irq_event_percpu+0xf0/0x438) from [<800a8b70>] (handle_irq_event+0x78/0xa0)
[<800a8b70>] (handle_irq_event+0x78/0xa0) from [<800abdac>] (handle_fasteoi_irq+0xd4/0x18c)
[<800abdac>] (handle_fasteoi_irq+0xd4/0x18c) from [<800a7e70>] (generic_handle_irq+0x40/0x50)
[<800a7e70>] (generic_handle_irq+0x40/0x50) from [<8000f7a4>] (handle_IRQ+0x68/0xbc)
[<8000f7a4>] (handle_IRQ+0x68/0xbc) from [<800084e8>] (gic_handle_irq+0x38/0x68)
[<800084e8>] (gic_handle_irq+0x38/0x68) from [<8064b100>] (__irq_svc+0x40/0x70)

Call Trace on PowerPC:
BUG: sleeping function called from invalid context at linux/kernel/rtmutex.c:658
in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/0
Call Trace:
[c0c0fd80] [c040a1b4] show_stack+0x10c/0x1c0 (unreliable)
[c0c0fdd0] [c09c3c48] dump_stack+0x24/0x34
[c0c0fde0] [c045f728] __might_sleep+0xd8/0xfc
[c0c0fdf0] [c09bb750] rt_spin_lock+0x34/0x7c
[c0c0fe00] [c0462e44] __wake_up+0x38/0x70
[c0c0fe20] [c04df740] perf_event_wakeup+0x40/0x90
[c0c0fe50] [c04df7d0] perf_pending_event+0x40/0x6c
[c0c0fe60] [c04da4d4] irq_work_run+0x84/0xc4
[c0c0fe80] [c040bd54] timer_interrupt+0x1ec/0x3d0
[c0c0fec0] [c0411728] ret_from_except+0x0/0x18

We can run the irq-work under softirq context to resolve this problemjust like x86 does.

Comment 1 Darren Hart 2013-04-25 14:44:57 UTC

Xufeng if you will be working this, please move the status to "Accepted" and review the Target Milestone. For a change like this, an earlier milestone is preferred to a later one.

Comment 2 Xufeng Zhang 2014-04-24 03:21:46 UTC

Patch has already been merged.