linux-kernel - RE: [PATCH] x86/hyper-v: guard against cpu mask changes in hyperv_flush_tlb

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Message-ID: <VI1PR0401MB2415F41E0D6B43411779911AF1C39@VI1PR0401MB2415.eurprd04.prod.outlook.com>
Date:   Sun, 22 Aug 2021 16:25:19 +0000
From:   David Mozes <david.mozes@...k.us>
To:     Wei Liu <wei.liu@...nel.org>
CC:     David Moses <mosesster@...il.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        תומר אבוטבו <tomer432100@...il.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] x86/hyper-v: guard against cpu mask changes in
 hyperv_flush_tlb_others()

This is not visible since we need a very high load to reproduce. 
We have tried a lot but can't achieve the desired load 
On our kernel with less load, it is not reproducible as well.

-----Original Message-----
From: Wei Liu <wei.liu@...nel.org> 
Sent: Sunday, August 22, 2021 6:25 PM
To: David Mozes <david.mozes@...k.us>
Cc: David Moses <mosesster@...il.com>; Wei Liu <wei.liu@...nel.org>; Michael Kelley <mikelley@...rosoft.com>; תומר אבוטבול <tomer432100@...il.com>; linux-hyperv@...r.kernel.org; linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/hyper-v: guard against cpu mask changes in hyperv_flush_tlb_others()

On Thu, Aug 19, 2021 at 07:55:06AM +0000, David Mozes wrote:
> Hi Wei ,
> I move the print cpumask to other two places after the treatment on the empty mask see below
> And I got the folwing:
> 
> 
> Aug 19 02:01:51 c-node05 kernel: [25936.562674] Hyper-V: ERROR_HYPERV2: cpu_last=
> Aug 19 02:01:51 c-node05 kernel: [25936.562686] WARNING: CPU: 11 PID: 56432 at arch/x86/include/asm/mshyperv.h:301 hyperv_flush_tlb_others+0x23f/0x7b0
> 
> So we got empty on different place on the code .
> Let me know if you need further information from us.
> How you sagest to handle this situation?
> 

Please find a way to reproduce this issue with upstream kernels.

Thanks,
Wei.