On 2020/10/29 4:04, Vishwanath Pai wrote: > On 10/28/20 1:47 PM, Cong Wang wrote: >> On Wed, Oct 28, 2020 at 8:37 AM Pai, Vishwanath <v...@akamai.com> wrote: >>> Hi, >>> >>> We noticed some problems when testing the latest 5.4 LTS kernel and traced >>> it >>> back to this commit using git bisect. When running our tests the machine >>> stops >>> responding to all traffic and the only way to recover is a reboot. I do not >>> see >>> a stack trace on the console. >> >> Do you mean the machine is still running fine just the network is down? >> >> If so, can you dump your tc config with stats when the problem is happening? >> (You can use `tc -s -d qd show ...`.) >> >>> >>> This can be reproduced using the packetdrill test below, it should be run a >>> few times or in a loop. You should hit this issue within a few tries but >>> sometimes might take up to 15-20 tries. >> ... >>> I can reproduce the issue easily on v5.4.68, and after reverting this >>> commit it >>> does not happen anymore. >> >> This is odd. The patch in this thread touches netdev reset path, if >> packetdrill >> is the only thing you use to trigger the bug (that is netdev is always >> active), >> I can not connect them. >> >> Thanks. > > Hi Cong, > >> Do you mean the machine is still running fine just the network is down? > > I was able to access the machine via serial console, it looks like it is > up and running, just that networking is down. > >> If so, can you dump your tc config with stats when the problem is happening? >> (You can use `tc -s -d qd show ...`.) > > If I try running tc when the machine is in this state the command never > returns. It doesn't print anything but doesn't exit either. > >> This is odd. The patch in this thread touches netdev reset path, if >> packetdrill >> is the only thing you use to trigger the bug (that is netdev is always >> active), >> I can not connect them. > > I think packetdrill creates a tun0 interface when it starts the > test and tears it down at the end, so it might be hitting this code path > during teardown.
Hi, Is there any preparation setup before running the above packetdrill test case, I run the above test case in 5.9-rc4 with this patch applied without any preparation setup, did not reproduce it. By the way, I am newbie to packetdrill:), it would be good to provide the detail setup to reproduce it,thanks. > > P.S: My mail server is having connectivity issues with vger.kernel.org > so messages aren't getting delivered to netdev. It'll hopefully get > resolved soon. > > Thanks, > Vishwanath > > > . >
