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

[Haiyang Zhang]

> -----Original Message-----
> From: Sitsofe Wheeler [mailto:sitsofe at gmail.com]
> Sent: Monday, July 14, 2014 5:31 PM
> To: Haiyang Zhang
> Cc: KY Srinivasan; David S. Miller; devel at linuxdriverproject.org; linux-
> kernel at vger.kernel.org; netdev at vger.kernel.org
> Subject: 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:
> > 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.

Thanks for the tests! I will make a patch that can automatically retry
smaller memory allocs when memory is insufficient.

Thanks,
- Haiyang