On Sunday, March 31, 2013 03:41:11 AM Rafael J. Wysocki wrote: > [Moving the thread to the LKML.] > > On Saturday, March 30, 2013 06:41:16 PM Sasha Levin wrote: > > On 03/15/2013 01:06 PM, Rafael J. Wysocki wrote: > [...] > > >> Rafael, Is there anything you would like me to test? > > > > > > Please just test 3.9-rc2 (or later). > > > > Hi Rafael, > > Hi, > > > I got this after a bit of fuzzing, it looks related to the fix: > > So the complaint is that we shouldn't call pm_qos_sysfs_remove_flags() under > dev_pm_qos_mtx, because then it may deadlock with dev_pm_qos_update_flags() > called from pm_qos_remote_wakeup_store(), for example. This appears to be a > valid one. > > To avoid that, we can use a separate mutex for exposing/hiding the flags > (and the latency limit too) that won't be acquired by dev_pm_qos_update_flags() > or dev_pm_qos_update_request(). > > Can you please try the patch below? Never mind, I have reproduced the lockdep splat and the patch fixes it for me. Moreover, I've discovered that we call dev_pm_qos_hide_flags() from usb_port_device_release(), which is totally incorrect. So, I have two patches (on top of the Linus' tree) that will follow shortly: [1/2] USB / PM: Don't try to hide PM QoS flags from usb_port_device_release() [2/2] PM / QoS: Avoid possible deadlock related to sysfs access Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
