Hi Will, On 14 April 2014 03:53, Will Deacon <will.dea...@arm.com> wrote: > On Tue, Mar 18, 2014 at 09:40:57PM +0000, 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/
