RE: [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@xxxxxxxxx]
> Sent: Friday, July 11, 2014 1:53 AM
> To: Haiyang Zhang
> Cc: KY Srinivasan; David S. Miller; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx
> Subject: Re: [BISECTED][REGRESSION] Loading Hyper-V network drivers is
> racy in 3.14+ on Hyper-V 2012 R2

> 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?

[    8.514493] hv_netvsc: hv_netvsc channel opened successfully
[    9.343318] hv_netvsc vmbus_0_14: Send section size: 6144, Section count:170
[    9.345831] hv_netvsc vmbus_0_14: Device MAC 00:15:5d:6f:02:8f link state up

[    9.347101] hv_netvsc: hv_netvsc channel opened successfully
[   10.170308] hv_netvsc vmbus_0_15: Send section size: 6144, Section count:170
[   10.170702] hv_netvsc vmbus_0_15: Device MAC 00:15:5d:6f:02:a5 link state up

[   10.172826] hv_netvsc: hv_netvsc channel opened successfully
[   10.988146] hv_netvsc vmbus_0_16: Send section size: 6144, Section count:170
[   10.989069] hv_netvsc vmbus_0_16: Device MAC 00:15:5d:6f:02:a6 link state down

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 */

Thanks,
- Haiyang

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