Date:	Wed, 23 Jan 2013 15:26:42 -0800
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Pasi Kärkkäinen <pasik@....fi>
Cc:	netdev@...r.kernel.org
Subject: Re: Linux 3.6.x kernel crash in tcp_slow_start / bictcp_cong_avoid
 with wfica

On Wed, 23 Jan 2013 23:51:51 +0200
Pasi Kärkkäinen <pasik@....fi> wrote:

> On Wed, Jan 23, 2013 at 10:44:45PM +0100, Hannes Frederic Sowa wrote:
> > On Wed, Jan 23, 2013 at 06:12:38PM +0200, Pasi Kärkkäinen wrote:
> > > My laptop running Fedora 17 randomly crashes when using wfica (Citrix Receiver / ICA Client) 
> > > proprietary closed source client for accessing remote desktop server. 
> > > wfica is running as a normal user, so it shouldn't be able to cause a kernel crash. 
> > > 
> > > Crashes seem to happen most often when I use either wlan- or 3G mobile data Internet connection. 
> > > These kernel crashes happen ramdomly, often 1-2 times a week. 
> > > What usually happens is that I notice the Internet connection has died, 
> > > and when I check the kernel dmesg I'm seeing the traceback. 
> > > At this point I'm still able to use the gnome desktop for maybe 1-5 minutes, 
> > > but applications start to fail one by one, and finally everything just halts 
> > > and I need to power cycle the laptop. 
> > 
> > Would it be possible to capture a strace -e network, so we could see which
> > setsockopt combinations are being applied to the socket. Is capturing ss -ioem
> > in such moments still possible?
> > 
> 
> I don't think I'm able to strace or anything at that point.. 
> It took me at least 10 tries (=crashes) before I was able to "dmesg > log.txt" successfully .. 
> (usually writing/redirecting to a file fails because the disk/fs is already unavailable..)
> 
> I can always try though!
> 
> Any other ideas? 

I see no problems when using Citrix.
This is a normal strace of the program wifca (in idle loop)


select(0, NULL, NULL, NULL, {0, 9902})  = 0 (Timeout)
setsockopt(11, SOL_SOCKET, SO_ERROR, [11], 4) = -1 ENOPROTOOPT (Protocol not available)
gettimeofday({1358983243, 665428}, NULL) = 0
gettimeofday({1358983243, 665750}, NULL) = 0
read(4, 0x84a59a0, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x84a59a0, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
gettimeofday({1358983243, 666322}, NULL) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=11, events=POLLIN}], 3, 88) = 0 (Timeout)
gettimeofday({1358983243, 754766}, NULL) = 0
gettimeofday({1358983243, 754964}, NULL) = 0
gettimeofday({1358983243, 755152}, NULL) = 0

Not the smartest program, on the block.

Here is what it looks like when getting data.

poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=11, events=POLLIN}], 3, 88) = 1 ([{fd=4, revents=POLLIN}])
read(4, "\7\3=.\202\2135\6\315\0\0\0\326\0`\3\0\0\0\0]\5/\2\347\4\24\2\20\0\0\2"..., 4096) = 96
read(4, 0x84a59a0, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
gettimeofday({1358983244, 918078}, NULL) = 0
gettimeofday({1358983244, 918303}, NULL) = 0
gettimeofday({1358983244, 918512}, NULL) = 0
gettimeofday({1358983244, 918666}, NULL) = 0
gettimeofday({1358983244, 918786}, NULL) = 0
send(11, "\27\3\1\0000q%\313\247\260\372\322\217\2272\362\270\242\215J\275\217IW=5\355\235@\0\365\211"..., 53, 0) = 53
gettimeofday({1358983244, 919012}, NULL) = 0
poll([{fd=4, events=POLLIN|POLLOUT}], 1, 4294967295) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\30\0\6\0\234\0`\3\1\0\0\0s\1\0\0s\1\0\0\202\2135\6f\0\5\0\16\0\0\0"..., 44}, {NULL, 0}, {"", 0}], 3) = 44
read(4, 0x84a59a0, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x84a59a0, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
gettimeofday({1358983244, 919542}, NULL) = 0

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