Re: [BISECTED][REGRESSION] Loading Hyper-V network drivers is racy in 3.14+ on Hyper-V 2012 R2

On Fri, Jul 11, 2014 at 03:25:11PM +0000, Haiyang Zhang wrote:

quoted

-----Original Message-----
From: Sitsofe Wheeler [mailto:sitsofe@gmail.com]
Sent: Friday, July 11, 2014 1:53 AM
To: Haiyang Zhang
Cc: KY Srinivasan; David S. Miller; devel@linuxdriverproject.org; linux-
kernel@vger.kernel.org; netdev@vger.kernel.org
Subject: Re: [BISECTED][REGRESSION] Loading Hyper-V network drivers is
racy in 3.14+ on Hyper-V 2012 R2

quoted

Oops that should have been
https://bugzilla.kernel.org/attachment.cgi?id=142351 (either way it's
information linked off
https://bugzilla.kernel.org/show_bug.cgi?id=78771 ).

Thanks for the dmesg. By looking at it, seems the netvsc driver was
loaded properly, and 2 NICs are up, one NIC is down (probably not set
to connected in HyperV manager?). Or, this dmesg wasn't the one when
bug happens?

This was a dmesg where the bug did happen and your first guess is right
- there are 3 NICs but only the first two are connected and the last is
set to "Not connected" in Hyper-V Manager.

Since you found the commit b679ef73edc is related to this problem,
could you do a simple test:
  Reduce the receive buffer size back to 2MB, like below, then re-test
  it, see if the problem goes away?
	drivers/net/hyperv/hyperv_net.h
	#define NETVSC_RECEIVE_BUFFER_SIZE		(1024*1024*2)	/* 2MB */

After doing this I was able to reach over 900 reboots where the network
connected properly.

-- 
Sitsofe | http://sucs.org/~sits/