On Thu, 30 Jul 2009, Aric D. Blumer wrote: > Can anyone give me some suggestions on the cause of this error and how > to go about debugging it? > > > # apm -s > > PM: Syncing filesystems ... done. > > Freezing user space processes ... (elapsed 0.00 seconds) done. > > Freezing remaining freezable tasks ... > > Freezing of tasks failed after 20.00 seconds (1 tasks refusing to freeze): > > (... Then it lists a bunch of tasks ...) > > runnable tasks: > > task PID tree-key switches prio exec-runtime sum-exec sum-sleep > > ---------------------------------------------------------------------------------------------------------- > > khubd 165 266235.124222 1605 115 0 0 0.000000 0.000000 0.000000 > > R apm 2103 268103.568767 85 120 0 0 0.000000 0.000000 0.000000 > > > > khubd > > This is with the 2.6.29 kernel (2.6.28 does it too), and it looks like > khubd is the culprit. This is on a PXA320-based system, so it's using > ohci-pxa27x.c. There are no USB client devices plugged in. In the task > list, it gives this stack trace about khubd: > > > khubd D c032c2d8 0 165 2 > > [<c032c130>] (schedule+0x0/0x2a4) from [<c032c60c>] (schedule_timeout+0x6c/0xd0) > > [<c032c5a0>] (schedule_timeout+0x0/0xd0) from [<c032c694>] (schedule_timeout_uninterruptible+0x24/0x28) > > r7:00000000 r6:c043db74 r5:00000000 r4:00000000 > > [<c032c670>] (schedule_timeout_uninterruptible+0x0/0x28) from [<c00510e4>] (msleep+0x1c/0x28) > > [<c00510c8>] (msleep+0x0/0x28) from [<c023288c>] (hub_thread+0x694/0xdfc) > > [<c02321f8>] (hub_thread+0x0/0xdfc) from [<c005bda0>] (kthread+0x50/0x7c) > > [<c005bd50>] (kthread+0x0/0x7c) from [<c004a044>] (do_exit+0x0/0x770) > > r5:00000000 r4:00000000 > > I think the 'D' status is key. The first time I run 'apm -s' it > succeeds in suspending. After I resume, though, top shows khubd as 'D' > (uninterruptible sleep), then it won't suspend. Why would that happen? You can get more information about what khubd is doing by turning on CONFIG_USB_DEBUG. Post the resulting dmesg log; it will most likely contain the answer to your question. Alan Stern -- 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
