Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart
Hi Will, On 14 April 2014 03:53, Will Deacon wrote: > On Tue, Mar 18, 2014 at 09:40:57PM +, Sebastian Capella wrote: >> Use of tracers in local_irq_disable is causes abort loops when called >> with irqs disabled using a temporary stack. Replace local_irq_disable >> with raw_local_irq_disable instead to avoid tracers. > > Do you have any more information about these aborts? At the time we call > local_irq_disable, the stack is still intact, so if the issue is simply > related to having any tracers active at the call_with_stack invocation, we'd > be better off disabling tracing here altogether. This is specifically for when soft_restart is called in the hibernation path with tracers enabled. At that point, we've already switched to a temporary stack, and when we call local_irq_disable, we'll see this: In the local_irq_disable, it ends up calling trace_hardirqs_off (CONFIG_TRACE_IRQFLAGS_SUPPORT is enabled), which calls trace_hardirqs_off_caller which checks lockdep_recursion in the current task, but we've switched to a temporary stack with the call_with_stack, and get_current is returning NULL. This triggers a data abort, which calls trace_hardirqs_off again and so on. We originally had a patch which added a soft restart called soft_restart_noirq which avoided the irq disable. You can see the discussion here: https://patchwork.kernel.org/patch/3677591/ Thanks! Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart
Hi Sebastian, On Tue, Mar 18, 2014 at 09:40:57PM +, Sebastian Capella wrote: > Use of tracers in local_irq_disable is causes abort loops when called > with irqs disabled using a temporary stack. Replace local_irq_disable > with raw_local_irq_disable instead to avoid tracers. Do you have any more information about these aborts? At the time we call local_irq_disable, the stack is still intact, so if the issue is simply related to having any tracers active at the call_with_stack invocation, we'd be better off disabling tracing here altogether. Will > Signed-off-by: Sebastian Capella > Cc: Russell King > Cc: Andrew Morton > Cc: Will Deacon > Cc: Robin Holt > Cc: Thomas Gleixner > Cc: Konstantin Khlebnikov > Cc: Steven Capper > Cc: Stephen Warren > Cc: Tejun Heo > --- > arch/arm/kernel/process.c |2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c > index 92f7b15..f58b723 100644 > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -100,7 +100,7 @@ void soft_restart(unsigned long addr) > u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack); > > /* Disable interrupts first */ > - local_irq_disable(); > + raw_local_irq_disable(); > local_fiq_disable(); > > /* Disable the L2 if we're the last man standing. */ > -- > 1.7.9.5 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart
Hi Will, On 14 April 2014 03:53, Will Deacon will.dea...@arm.com wrote: On Tue, Mar 18, 2014 at 09:40:57PM +, Sebastian Capella wrote: Use of tracers in local_irq_disable is causes abort loops when called with irqs disabled using a temporary stack. Replace local_irq_disable with raw_local_irq_disable instead to avoid tracers. Do you have any more information about these aborts? At the time we call local_irq_disable, the stack is still intact, so if the issue is simply related to having any tracers active at the call_with_stack invocation, we'd be better off disabling tracing here altogether. This is specifically for when soft_restart is called in the hibernation path with tracers enabled. At that point, we've already switched to a temporary stack, and when we call local_irq_disable, we'll see this: In the local_irq_disable, it ends up calling trace_hardirqs_off (CONFIG_TRACE_IRQFLAGS_SUPPORT is enabled), which calls trace_hardirqs_off_caller which checks lockdep_recursion in the current task, but we've switched to a temporary stack with the call_with_stack, and get_current is returning NULL. This triggers a data abort, which calls trace_hardirqs_off again and so on. We originally had a patch which added a soft restart called soft_restart_noirq which avoided the irq disable. You can see the discussion here: https://patchwork.kernel.org/patch/3677591/ Thanks! Sebastian -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v9 1/2] ARM: avoid tracers in soft_restart
Hi Sebastian, On Tue, Mar 18, 2014 at 09:40:57PM +, Sebastian Capella wrote: Use of tracers in local_irq_disable is causes abort loops when called with irqs disabled using a temporary stack. Replace local_irq_disable with raw_local_irq_disable instead to avoid tracers. Do you have any more information about these aborts? At the time we call local_irq_disable, the stack is still intact, so if the issue is simply related to having any tracers active at the call_with_stack invocation, we'd be better off disabling tracing here altogether. Will Signed-off-by: Sebastian Capella sebastian.cape...@linaro.org Cc: Russell King li...@arm.linux.org.uk Cc: Andrew Morton a...@linux-foundation.org Cc: Will Deacon will.dea...@arm.com Cc: Robin Holt h...@sgi.com Cc: Thomas Gleixner t...@linutronix.de Cc: Konstantin Khlebnikov k.khlebni...@samsung.com Cc: Steven Capper steve.cap...@linaro.org Cc: Stephen Warren swar...@nvidia.com Cc: Tejun Heo t...@kernel.org --- arch/arm/kernel/process.c |2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 92f7b15..f58b723 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -100,7 +100,7 @@ void soft_restart(unsigned long addr) u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack); /* Disable interrupts first */ - local_irq_disable(); + raw_local_irq_disable(); local_fiq_disable(); /* Disable the L2 if we're the last man standing. */ -- 1.7.9.5 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v9 1/2] ARM: avoid tracers in soft_restart
Use of tracers in local_irq_disable is causes abort loops when called with irqs disabled using a temporary stack. Replace local_irq_disable with raw_local_irq_disable instead to avoid tracers. Signed-off-by: Sebastian Capella Cc: Russell King Cc: Andrew Morton Cc: Will Deacon Cc: Robin Holt Cc: Thomas Gleixner Cc: Konstantin Khlebnikov Cc: Steven Capper Cc: Stephen Warren Cc: Tejun Heo --- arch/arm/kernel/process.c |2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 92f7b15..f58b723 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -100,7 +100,7 @@ void soft_restart(unsigned long addr) u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack); /* Disable interrupts first */ - local_irq_disable(); + raw_local_irq_disable(); local_fiq_disable(); /* Disable the L2 if we're the last man standing. */ -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v9 1/2] ARM: avoid tracers in soft_restart
Use of tracers in local_irq_disable is causes abort loops when called with irqs disabled using a temporary stack. Replace local_irq_disable with raw_local_irq_disable instead to avoid tracers. Signed-off-by: Sebastian Capella sebastian.cape...@linaro.org Cc: Russell King li...@arm.linux.org.uk Cc: Andrew Morton a...@linux-foundation.org Cc: Will Deacon will.dea...@arm.com Cc: Robin Holt h...@sgi.com Cc: Thomas Gleixner t...@linutronix.de Cc: Konstantin Khlebnikov k.khlebni...@samsung.com Cc: Steven Capper steve.cap...@linaro.org Cc: Stephen Warren swar...@nvidia.com Cc: Tejun Heo t...@kernel.org --- arch/arm/kernel/process.c |2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 92f7b15..f58b723 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -100,7 +100,7 @@ void soft_restart(unsigned long addr) u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack); /* Disable interrupts first */ - local_irq_disable(); + raw_local_irq_disable(); local_fiq_disable(); /* Disable the L2 if we're the last man standing. */ -- 1.7.9.5 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/