Messages in this thread | | | Date | Mon, 20 Nov 2006 14:23:35 -0500 | From | Vivek Goyal <> | Subject | Re: [RFC] [PATCH] Fix misrouted interrupts deadlocks |
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On Fri, Nov 10, 2006 at 04:55:48PM +0300, Pavel Emelianov wrote: > As the second lock on booth 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. > > Please comment.
> --- ./kernel/irq/spurious.c.irqlockup 2006-11-09 11:19:10.000000000 +0300 > +++ ./kernel/irq/spurious.c 2006-11-10 16:53:38.000000000 +0300 > @@ -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);
Hi Pavel,
Till -rc5, I was able to boot a kernel with irqpoll option and in -rc6 I can't. It simply hangs. I suspect it is realted to this change. I have yet to confirm that. But before that one observation.
Not at every place note_interrupt() is called with desc->lock() held. For example, handle_level_irq(). I enabled spin lock debugging and I run into following BUG().
PID hash table entries: 256 (order: 8, 2048 bytes) time.c: Using 3.579545 MHz WALL PM GTOD PIT/TSC timer. time.c: Detected 3000.218 MHz processor.
===================================== [ BUG: bad unlock balance detected! ] ------------------------------------- swapper/0 is trying to release lock (&irq_desc_lock_class) at: [<ffffffff8104c673>] note_interrupt+0x7a/0x22b but there are no more locks to release!
other info that might help us debug this: no locks held by swapper/0.
stack backtrace:
Call Trace: [<ffffffff8100a6f9>] show_trace+0x34/0x47 [<ffffffff8100a71e>] dump_stack+0x12/0x17 [<ffffffff8103caba>] print_unlock_inbalance_bug+0xfb/0x106 [<ffffffff8103e6e5>] lock_release+0x89/0x128 [<ffffffff81332d96>] _spin_unlock+0x17/0x20 [<ffffffff8104c673>] note_interrupt+0x7a/0x22b [<ffffffff8104d131>] handle_level_irq+0xab/0xea [<ffffffff8100b776>] do_IRQ+0xf4/0x132 [<ffffffff81009956>] ret_from_intr+0x0/0xf DWARF2 unwinder stuck at ret_from_intr+0x0/0xf Leftover inexact backtrace:
<IRQ> <EOI> [<ffffffff8159f61d>] start_kernel+0x178/0x2f6 [<ffffffff8159f625>] start_kernel+0x180/0x2f6 [<ffffffff8159f61d>] start_kernel+0x178/0x2f6 [<ffffffff8159f13e>] _sinittext+0x13e/0x142
BUG: spinlock lockup on CPU#0, swapper/0, ffffffff81586140
Call Trace: [<ffffffff8100a6f9>] show_trace+0x34/0x47 [<ffffffff8100a71e>] dump_stack+0x12/0x17 [<ffffffff811457c8>] _raw_spin_lock+0xca/0xe8 [<ffffffff8104d139>] handle_level_irq+0xb3/0xea [<ffffffff8100b776>] do_IRQ+0xf4/0x132 [<ffffffff81009956>] ret_from_intr+0x0/0xf DWARF2 unwinder stuck at ret_from_intr+0x0/0xf
Leftover inexact backtrace:
<IRQ> <EOI> [<ffffffff8159f61d>] start_kernel+0x178/0x2f6 [<ffffffff8159f625>] start_kernel+0x180/0x2f6 [<ffffffff8159f61d>] start_kernel+0x178/0x2f6 [<ffffffff8159f13e>] _sinittext+0x13e/0x142
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