On 11/27/2013 02:59 PM, Sarah Sharp wrote:
On Mon, Nov 25, 2013 at 11:41:47AM -0700, Shuah Khan wrote:I started seeing the following on my Samsung Series on 3.12.1 Is this bad? Looks like the following WARN_ON is firing: drivers/usb/host/xhci.c: if (WARN_ON(!virt_dev)) { /* * In plug/unplug torture test with an NEC controller, * a zero-dereference was observed once due to virt_dev = 0. * Print useful debug rather than crash if it is observed again! */ xhci_warn(xhci, "Virt dev invalid for slot_id 0x%x!\n", udev->slot_id); return -EINVAL; }As the comment says, the WARN_ON was there so we can track down why this specific NULL pointer dereference bug could have been hit. What are the specific steps to reproduce this? It looks like it's coming from a device resume path. Did you have auto-suspend enabled for your USB devices, or did this warning occur right after an S3 resume? Can you enable CONFIG_USB_DEBUG and CONFIG_DYNAMIC_DEBUG, and send me dmesg starting from just before you trigger the WARN_ON()? I need to see what the xHCI driver state that causes this might be. Sarah Sharp
I forgot to mention that this problem is seen when I run suspend-to-disk test in reboot mode. Reproduced it again on 3.12.2-rc1 once and dmesg buffer wrapped around before I could save the log.
I enabled CONFIG_USB_DEBUG and I already had CONFIG_DYNAMIC_DEBUG enabled in config.
It doesn't seem to happen every time I to suspend-to-disk. I will try again and send you the log.
-- Shuah -- Shuah Khan Senior Linux Kernel Developer - Open Source Group Samsung Research America(Silicon Valley) shuah.kh@xxxxxxxxxxx | (970) 672-0658 -- 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
