Hi, In testing we were noticing that we were getting some intermittent crashes in profile_tick() when dyntick was enabled.
The crashes were because the frame pointer per_cpu____irq_regs value was 0. That code does a user_mode(get_irq_regs()). Currently regs is set only upon real hardware entry on an irq. The crash path shows resend_irqs() could be called with in a context where set_irq_regs() was not executed. In one specific case this was from softirq->tasklet_action(resend_tasklet)->resend_irqs->handle_level_irq-> handle_IRQ_event->...->profile_tick. It seems anyone calling kernel/irq/manage.c:enable_irq() at the wrong time can trigger this crash. Creating a fake stack and doing a set_irq_regs() fixes the crash. Would it be useful to set a pointer to the entry context on all state changes? For ease I just hacked a default fake stack into the init process after fork time so there is never a 0 but that doesn't seem so nice. Regards, Richard W. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
