Messages in this thread | | | Subject | Re: net: hang in unregister_netdevice: waiting for lo to become free | From | Tommi Rantala <> | Date | Wed, 21 Feb 2018 16:53:54 +0200 |
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On 20.02.2018 18:26, Neil Horman wrote: > On Tue, Feb 20, 2018 at 09:14:41AM +0100, Dmitry Vyukov wrote: >> On Tue, Feb 20, 2018 at 8:56 AM, Tommi Rantala >> <tommi.t.rantala@nokia.com> wrote: >>> On 19.02.2018 20:59, Dmitry Vyukov wrote: >>>> Is this meant to be fixed already? I am still seeing this on the >>>> latest upstream tree. >>>> >>> >>> These two commits are in v4.16-rc1: >>> >>> commit 4a31a6b19f9ddf498c81f5c9b089742b7472a6f8 >>> Author: Tommi Rantala <tommi.t.rantala@nokia.com> >>> Date: Mon Feb 5 21:48:14 2018 +0200 >>> >>> sctp: fix dst refcnt leak in sctp_v4_get_dst >>> ... >>> Fixes: 410f03831 ("sctp: add routing output fallback") >>> Fixes: 0ca50d12f ("sctp: fix src address selection if using secondary >>> addresses") >>> >>> >>> commit 957d761cf91cdbb175ad7d8f5472336a4d54dbf2 >>> Author: Alexey Kodanev <alexey.kodanev@oracle.com> >>> Date: Mon Feb 5 15:10:35 2018 +0300 >>> >>> sctp: fix dst refcnt leak in sctp_v6_get_dst() >>> ... >>> Fixes: dbc2b5e9a09e ("sctp: fix src address selection if using secondary >>> addresses for ipv6") >>> >>> >>> I guess we missed something if it's still reproducible. >>> >>> I can check it later this week, unless someone else beat me to it. >> >> Hi Tommi, >> >> Hmmm, I can't claim that it's exactly the same bug. Perhaps it's >> another one then. But I am still seeing these: >> >> [ 58.799130] unregister_netdevice: waiting for lo to become free. >> Usage count = 4 >> [ 60.847138] unregister_netdevice: waiting for lo to become free. >> Usage count = 4 >> [ 62.895093] unregister_netdevice: waiting for lo to become free. >> Usage count = 4 >> [ 64.943103] unregister_netdevice: waiting for lo to become free. >> Usage count = 4 >> >> on upstream tree pulled ~12 hours ago. >> > Can you write a systemtap script to probe dev_hold, and dev_put, printing out a > backtrace if the device name matches "lo". That should tell us definitively if > the problem is in the same location or not
Hi Dmitry, I tested with the reproducer and the kernel .config file that you sent in the first email in this thread:
With 4.16-rc2 unable to reproduce.
With 4.15-rc9 bug reproducible, and I get "unregister_netdevice: waiting for lo to become free. Usage count = 3"
With 4.15-rc9 and Alexey's "sctp: fix dst refcnt leak in sctp_v6_get_dst()" cherry-picked on top, unable to reproduce.
Is syzkaller doing something else now to trigger the bug...? Can you still trigger the bug with the same reproducer?
Tommi
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