The patch titled Fix misrouted interrupts deadlocks has been removed from the -mm tree. Its filename was fix-misrouted-interrupts-deadlocks.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ Subject: Fix misrouted interrupts deadlocks From: Pavel Emelianov <xemul@xxxxxxxxxx> While testing kernel on machine with "irqpoll" option I've caught such a lockup: __do_IRQ() spin_lock(&desc->lock); desc->chip->ack(); /* IRQ is ACKed */ note_interrupt() misrouted_irq() handle_IRQ_event() if (...) local_irq_enable_in_hardirq(); /* interrupts are enabled from now */ ... __do_IRQ() /* same IRQ we've started from */ spin_lock(&desc->lock); /* LOCKUP */ Looking at misrouted_irq() code I've found that a potential deadlock like this can also take place: 1CPU: __do_IRQ() spin_lock(&desc->lock); /* irq = A */ misrouted_irq() for (i = 1; i < NR_IRQS; i++) { spin_lock(&desc->lock); /* irq = B */ if (desc->status & IRQ_INPROGRESS) { 2CPU: __do_IRQ() spin_lock(&desc->lock); /* irq = B */ misrouted_irq() for (i = 1; i < NR_IRQS; i++) { spin_lock(&desc->lock); /* irq = A */ if (desc->status & IRQ_INPROGRESS) { As the second lock on both CPUs is taken before checking that this irq is being handled in another processor this may cause a deadlock. This issue is only theoretical. I propose the attached patch to fix booth problems: when trying to handle misrouted IRQ active desc->lock may be unlocked. Acked-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxx> --- kernel/irq/spurious.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff -puN kernel/irq/spurious.c~fix-misrouted-interrupts-deadlocks kernel/irq/spurious.c --- a/kernel/irq/spurious.c~fix-misrouted-interrupts-deadlocks +++ a/kernel/irq/spurious.c @@ -147,7 +147,11 @@ void note_interrupt(unsigned int irq, st if (unlikely(irqfixup)) { /* Don't punish working computers */ if ((irqfixup == 2 && irq == 0) || action_ret == IRQ_NONE) { - int ok = misrouted_irq(irq); + int ok; + + spin_unlock(&desc->lock); + ok = misrouted_irq(irq); + spin_lock(&desc->lock); if (action_ret == IRQ_NONE) desc->irqs_unhandled -= ok; } _ Patches currently in -mm which might be from xemul@xxxxxxxxxx are origin.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html