RE: [PATCH RESEND 1/8] Drivers: hv: vmbus: prevent cpu offlining on newer hypervisors

From: KY Srinivasan
Date: Wed Jan 28 2015 - 20:50:54 EST




> -----Original Message-----
> From: K. Y. Srinivasan [mailto:kys@xxxxxxxxxxxxx]
> Sent: Tuesday, January 27, 2015 3:47 PM
> To: gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx;
> vkuznets@xxxxxxxxxx; tglx@xxxxxxxxxxxxx
> Cc: KY Srinivasan
> Subject: [PATCH RESEND 1/8] Drivers: hv: vmbus: prevent cpu offlining on
> newer hypervisors
>
> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>
> When an SMP Hyper-V guest is running on top of 2012R2 Server and
> secondary cpus are sent offline (with echo 0 >
> /sys/devices/system/cpu/cpu$cpu/online)
> the system freeze is observed. This happens due to the fact that on newer
> hypervisors (Win8, WS2012R2, ...) vmbus channel handlers are distributed
> across all cpus (see init_vp_index() function in drivers/hv/channel_mgmt.c)
> and on cpu offlining nobody reassigns them to CPU0. Prevent cpu offlining
> when vmbus is loaded until the issue is fixed host-side.
>
> This patch also disables hibernation but it is OK as it is also broken (MCE error
> is hit on resume). Suspend still works.
>
> Tested with WS2008R2 and WS2012R2.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>

Greg,

Please drop this entire series; the patch-set was based on the incorrect tree. I will resend the set shortly
after rebasing them on your char-misc.git.

Thank you,

K. Y
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