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Message-ID: <1515248235.17396.4.camel@gmail.com>
Subject: Re: Google Chrome cause locks held in system (kernel 4.15 rc2)
From: mikhail <mikhail.v.gavrilov@gmail.com>
Date: Sat, 06 Jan 2018 19:17:15 +0500
In-Reply-To: <201712110348.vBB3mSFZ068689@www262.sakura.ne.jp>
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To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: mhocko@kernel.org, darrick.wong@oracle.com, linux-xfs@vger.kernel.org, linux-mm@kvack.org

On Mon, 2017-12-11 at 12:48 +0900, Tetsuo Handa wrote:
> mikhail wrote:
> > > > netconsole works only within local network? destination ip may
> > > > be from
> > > > another network?
> > > 
> > > netconsole can work with another network.
> > > 
> > > (step 1) Verify that UDP packets are reachable. You can test with
> > > 
> > >          # echo test > /dev/udp/213.136.82.171/6666
> > > 
> > >          if you are using bash.
> > 
> > After this on remote machine was created folder with name of router
> > external ip address.
> > Inside this folder was places one file with name of current day.
> > This
> > file has size 0 of bytes and not contain "test" message inside.
> > That is how it should be?
> 
> The message should be written to the log file. If not written, UDP
> packets
> are dropped somewhere. You need to solve this problem first.

I found root cause this problem. Here culprit udplogger, because it not
flush buffers when terminated by ctrl-c.

Here my pull request with fix this problem:
https://github.com/kohsuke/udplogger/pull/1/

Also i fixed two segfault:

1) When send two messages in one second from different hosts or ports.
For reproduce just run
"echo test > /dev/udp/127.0.0.1/6666 && echo test >
/dev/udp/127.0.0.1/6666"
in console.

2) When exced limit of open files.
Just run "echo test > /dev/udp/127.0.0.1/6666" more than 1024 times.