Messages in this thread Patch in this message | | | From | "Liu, Chuansheng" <> | Subject | RE: [REGRESSION] 3.7-rc3+git hard lockup on CPU after inserting/removing USB stick | Date | Tue, 13 Nov 2012 00:47:31 +0000 |
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> -----Original Message----- > From: Thomas Gleixner [mailto:tglx@linutronix.de] > Sent: Tuesday, November 13, 2012 3:32 AM > To: Martin Steigerwald > Cc: Liu, Chuansheng; linux-kernel@vger.kernel.org; Ingo Molnar; Greg > Kroah-Hartman > Subject: Re: [REGRESSION] 3.7-rc3+git hard lockup on CPU after > inserting/removing USB stick > > On Mon, 12 Nov 2012, Martin Steigerwald wrote: > > Am Sonntag, 11. November 2012 schrieb Liu, Chuansheng: > > > > The first bad commit is: > > > > > > > > commit 73d4066055e0e2830533041f4b91df8e6e5976ff > > > > Author: Chuansheng Liu <chuansheng.liu@intel.com> > > > > Date: Tue Sep 11 16:00:30 2012 +0800 > > > > > > > > USB/host: Cleanup unneccessary irq disable code > > > > > > > > Because the IRQF_DISABLED as the flag is now a NOOP and has > been > > > > deprecated and in hardirq context the interrupt is disabled. > > > > > > > > so in usb/host code: > > > > Removing the usage of flag IRQF_DISABLED; > > > > Removing the calling local_irq save/restore actions in irq > > > > handler usb_hcd_irq(); > > > > > > > > Signed-off-by: liu chuansheng <chuansheng.liu@intel.com> > > > > Acked-by: Alan Stern <stern@rowland.harvard.edu> > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > > > > > > > > > > But: > > > > > > > > This ony happens with threadirqs option! > > > > > > > > When I remove threadirqs from kernel command line and reboot with this > > > > last bisect kernel USB sticks work. > > > > > > > > That may explain why nobody else has seen this. > > > > > > > > So I will try a 3.7-rc4 now, but without threadirqs enabled. > > > > > > > Thanks your pointing out, the USB HCD irq handler is designed to > > > execute in irq handler with irq disabled. When threadirqs is in > > > commandline, it will be executed in thread context with local irq > > > enabling, which causes this hardlockup. > > No. The problem is caused by the commit above. USB with threaded > interrupt handlers worked perfectly fine in the past. The reason is that removing local_irq_save/restore() in function usb_hcd_irq(). The hard lockup analysis is: CPU3 Usb_hcd_irq() --> ehci_irq --> spin_lock (&ehci->lock); ... if (status == ~(u32) 0) {
At this time, one hrtimer is coming: ehci_hrtimer_func() --> spin_lock_irqsave(&ehci->lock, flags);
Due to the spin_lock has been hold before, it causes the deadlock.
The dmesg is as below: [ 155.010424] [<ffffffff814027b0>] ? _raw_spin_lock_irqsave+0x3f/0x48 [ 155.010649] [<ffffffff814027b0>] ? _raw_spin_lock_irqsave+0x3f/0x48 [ 155.010884] [<ffffffff814027b0>] ? _raw_spin_lock_irqsave+0x3f/0x48 [ 155.011104] <<EOE>> <IRQ> [<ffffffffa00c6836>] ehci_hrtimer_func+0x28/0xb5 [ehci_hcd] [ 155.011446] [<ffffffff8105dc7d>] ? __remove_hrtimer+0x31/0x8b [ 155.011661] [<ffffffffa00c680e>] ? end_free_itds+0x108/0x108 [ehci_hcd] [ 155.011911] [<ffffffff8105e116>] __run_hrtimer+0xb9/0x176 [ 155.012105] [<ffffffff8105e804>] hrtimer_interrupt+0xcb/0x1b4 [ 155.012311] [<ffffffff810a4b6d>] ? irq_thread_fn+0x35/0x35 [ 155.012509] [<ffffffff8102abc2>] smp_apic_timer_interrupt+0x71/0x84 [ 155.012742] [<ffffffff81407b4a>] apic_timer_interrupt+0x6a/0x70 [ 155.012950] <EOI> [<ffffffffa00c9087>] ? ehci_irq+0x39/0x267 [ehci_hcd] [ 155.013230] [<ffffffff81401830>] ? __schedule+0x57f/0x5b2 [ 155.013424] [<ffffffff810a4b6d>] ? irq_thread_fn+0x35/0x35 [ 155.013645] [<ffffffffa003befc>] usb_hcd_irq+0x20/0x2f [usbcore] [ 155.013874] [<ffffffff810a4b8d>] irq_forced_thread_fn+0x20/0x3e
> > > > --- a/drivers/usb/core/hcd.c > > > +++ b/drivers/usb/core/hcd.c > > > @@ -2349,7 +2349,7 @@ static int usb_hcd_request_irqs(struct usb_hcd > *hcd, > > > if (hcd->driver->irq) { > > > snprintf(hcd->irq_descr, sizeof(hcd->irq_descr), > "%s:usb%d", > > > hcd->driver->description, > hcd->self.busnum); > > > - retval = request_irq(irqnum, &usb_hcd_irq, irqflags, > > > + retval = request_irq(irqnum, &usb_hcd_irq, > irqflags|IRQF_NO_THREAD, > > > hcd->irq_descr, hcd); > > NAK. This is exactly the wrong thing to do. > > We want to be able to run that code in an handler thread. So you As Martin's experience: "I think that thread IRQs for USB based interrupts might not be a good from another experience." Maybe it shows something.
> removed the local_irq_save/restore() in the driver code and with > forced threaded irqs this breaks. Now setting IRQF_NO_THREAD is just > working around the problem that the above commit broke it. > > There is no hard requirement to run USB interrupts in hard interrupt > context. I'd rather see the above commit reverted and then a proper > analysis done why removing local_irq_save/restore() breaks forced > threaded interrupt handlers. As you said, we can revert the patch directly, or submit a new patch to just add local_irq_save/restore() back. Anyway, hardlock reason is there. Opinion?
> > Thanks, > > tglx
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