----- Original Message -----
From: "Kevin Hilman" <khilman@xxxxxxxxxxxxxxxxxxx>
To: "Pandita, Vikram" <vikram.pandita@xxxxxx>
Cc: <linux-omap@xxxxxxxxxxxxxxx>
Sent: Tuesday, August 11, 2009 8:57 PM
Subject: Re: Warnings: pm branch
"Pandita, Vikram" <vikram.pandita@xxxxxx> writes:
Has anyone send these warning logs on the pm branch on kevin's tree [1]
This seems to be some issue in CpuIdle path with interrupts?
<4>WARNING: at arch/arm/kernel/process.c:171 cpu_idle+0x60/0x88()
WARNING: at arch/arm/kernel/process.c:171 cpu_idle+0x60/0x88()
<d>Modules linked in:Modules linked in:
[<c0031344>] [<c0031344>] (unwind_backtrace+0x0/0xdc)
(unwind_backtrace+0x0/0xdc
) from [<c0057a08>] from [<c0057a08>] (warn_slowpath_common+0x48/0x60)
(warn_slowpath_common+0x48/0x60)
[<c0057a08>] [<c0057a08>] (warn_slowpath_common+0x48/0x60)
(warn_slowpath_common
+0x48/0x60) from [<c002d204>] from [<c002d204>] (cpu_idle+0x60/0x88)
(cpu_idle+0x60/0x88)
[<c002d204>] [<c002d204>] (cpu_idle+0x60/0x88) (cpu_idle+0x60/0x88) from
[<c0008
a70>] from [<c0008a70>] (start_kernel+0x234/0x28c)
(start_kernel+0x234/0x28c)
[<c0008a70>] [<c0008a70>] (start_kernel+0x234/0x28c)
(start_kernel+0x234/0x28c)
from [<80008034>] from [<80008034>] (0x80008034)
(0x80008034)
Yes, I've seen it, but have yet to debug it.
This warning is from the generic ARM idle loop reporting that the OMAP
idle path is returning with IRQs disabled.
Kevin
I did some more debugging on this. I added the below instrumentation to
local_irq_disable to capture
the PC of the last call to local_irq_disable.
extern unsigned long hem_pc;
register unsigned long current_pc asm ("pc");
#define local_irq_disable() \
do { hem_pc = current_pc;raw_local_irq_disable();
trace_hardirqs_off(); } while (0)
When I set a breakpoint at the instruction pointing to
WARN_ON(irqs_disabled()) using
lauterbach and dump hem_pc, I see that the last call to irq_disable is
actuall from cpu_idle itself.
Looks like some recursion is happening. Does anyone have any inputs on this.
void cpu_idle(void)
{
local_fiq_enable();
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_stop_sched_tick(1);
leds_event(led_idle_start);
while (!need_resched()) {
#ifdef CONFIG_HOTPLUG_CPU
if (cpu_is_offline(smp_processor_id()))
cpu_die();
#endif
local_irq_disable();
Thanks
Hemanth
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