On Wednesday 02 December 2009, Oliver Neukum wrote: > Am Mittwoch, 2. Dezember 2009 09:52:08 schrieb Ondrej Zary: > > It shows "prev is NULL, qh=f6581080, ehci->async=f6581000". > > > > The problem is that activating usbmon causes the problem to disappear. No > > errors in maybe 15 attempts. It appeared on 2nd attempt after unloading > > usbmon. > > That suggests a use after free bug, which usbmon prevents holding > an additional reference. > Are you using SLAB_DEBUG? Just tried 2.6.32-rc8-next-20091202 with SLAB_DEBUG enabled and got this: BUG: unable to handle kernel paging request at 6b6b6b6b IP: [<f7c649a3>] qh_completions+0x6c/0x400 Call Trace: lapic_next_event ehci_work tick_dev_program_event tick_program_event hrtimer_interrupt ehci_watchdog+0x0/0x37 ehci_watchdog+0x2b/0x37 run_timer_softirq __do_softirq irq_exit do_IRQ common_interrupt acpi_idle_enter_bm cpuidle_idle_call cpu_idle start_kernel Code: 00 00 00 00 3c 03 88 44 24 1f 0f 94 c0 81 ea ec 00 00 00 0f b6 c0 89 44 24 14 89 14 24 8b 46 0c 31 db bd 8d ff ff ff c6 46 28 00 <8b> 08 89 4c 24 10 e9 ec 02 00 00 83 e8 38 85 db 89 44 24 24 8b -- Ondrej Zary -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
