On Wed, Aug 9, 2017 at 5:36 PM, Wei Wang <wei...@google.com> wrote: > On Wed, Aug 9, 2017 at 4:44 PM, John Stultz <john.stu...@linaro.org> wrote: >> On Wed, Aug 9, 2017 at 4:34 PM, Cong Wang <xiyou.wangc...@gmail.com> wrote: >>> (Cc'ing Wei whose commit was blamed) >>> >>> On Mon, Aug 7, 2017 at 2:15 PM, John Stultz <john.stu...@linaro.org> wrote: >>>> On Mon, Aug 7, 2017 at 2:05 PM, John Stultz <john.stu...@linaro.org> wrote: >>>>> So, with recent testing with my HiKey board, I've been noticing some >>>>> quirky behavior with my USB eth adapter. >>>>> >>>>> Basically, pluging the usb eth adapter in and then removing it, when >>>>> plugging it back in I often find that its not detected, and the system >>>>> slowly spits out the following message over and over: >>>>> unregister_netdevice: waiting for eth0 to become free. Usage count = 1 >>>> >>>> The other bit is that after this starts printing, the board will no >>>> longer reboot (it hangs continuing to occasionally print the above >>>> message), and I have to manually reset the device. >>>> >>> >>> So this warning is not temporarily shown but lasts until a reboot, >>> right? If so it is a dst refcnt leak. >> >> Correct, once I get into the state it lasts until a reboot. >> >>> How reproducible is it for you? From my reading, it seems always >>> reproduced when you unplug and plug your usb eth interface? >>> Is there anything else involved? For example, network namespace. >> >> So with 4.13-rc3/4 I seem to trigger it easily, often with the first >> unplug of the USB eth adapter. >> >> But as I get back closer to 4.12, it seemingly becomes harder to >> trigger, but sometimes still happens. >> >> So far, I've not been able to trigger it with 4.12. >> >> I don't think network namespaces are involved? Though its out of my >> area, so AOSP may be using them these days. Is there a simple way to >> check? >> >> I'll also do another bisection to see if the bad point moves back any >> further.
So I went through another bisection around and got 9514528d92d4 ipv6: call dst_dev_put() properly as the first bad commit again. > If you see the problem starts to happen on commit > 9514528d92d4cbe086499322370155ed69f5d06c, could you try reverting all > the following commits: > (from new to old) > 1eb04e7c9e63 net: reorder all the dst flags > a4c2fd7f7891 net: remove DST_NOCACHE flag > b2a9c0ed75a3 net: remove DST_NOGC flag > 5b7c9a8ff828 net: remove dst gc related code > db916649b5dd ipv6: get rid of icmp6 dst garbage collector > 587fea741134 ipv6: mark DST_NOGC and remove the operation of dst_free() > ad65a2f05695 ipv6: call dst_hold_safe() properly > 9514528d92d4 ipv6: call dst_dev_put() properly And reverting this set off of 4.13-rc4 seems to make the issue go away. Is there anything I can test to help narrow down the specific problem with that patchset? thanks -john
