Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-30 Thread Greg KH 
On Tue, Mar 28, 2017 at 04:14:09PM +, Stephen Hemminger wrote:
> I decided not to send it to stable since problem was only observed on
> 4.11 but it is probably endemic to all GEN2 VM's

So, what does this mean?  What should stable@ do?  Nothing?  Ok, now
dropped this from my patch queue :)

thanks,

greg k-h

Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-30 Thread Greg KH 
On Tue, Mar 28, 2017 at 04:14:09PM +, Stephen Hemminger wrote:
> I decided not to send it to stable since problem was only observed on
> 4.11 but it is probably endemic to all GEN2 VM's

So, what does this mean?  What should stable@ do?  Nothing?  Ok, now
dropped this from my patch queue :)

thanks,

greg k-h

RE: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-28 Thread Stephen Hemminger 
I decided not to send it to stable since problem was only observed on 4.11 but 
it is probably endemic to all GEN2 VM's

-Original Message-
From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
Sent: Tuesday, March 28, 2017 7:29 AM
To: Stephen Hemminger <sthem...@microsoft.com>; Long Li <lon...@microsoft.com>
Cc: KY Srinivasan <k...@microsoft.com>; Martin K. Petersen 
<martin.peter...@oracle.com>; Haiyang Zhang <haiya...@microsoft.com>; 
j...@linux.vnet.ibm.com; de...@linuxdriverproject.org; linux-scsi 
<linux-s...@vger.kernel.org>; LKML <linux-kernel@vger.kernel.org>; 
sta...@vger.kernel.org; Greg KH <gre...@linuxfoundation.org>
Subject: Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
scsi: storvsc: properly set residual data length on errors

On 03/27/2017 06:14 PM, Stephen Hemminger wrote:
> Are you sure the real problem is not the one fixed by this commit?
>
> commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> Author: Stephen Hemminger <step...@networkplumber.org>
> Date:   Tue Mar 7 09:15:53 2017 -0800
>
> scsi: storvsc: Workaround for virtual DVD SCSI version
> 
> Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
> version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
> 
> Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
> successfully with virtual DVD ROM device. What happens is that the SCSI
> scan process falls back to doing sequential probing by INQUIRY.  But the
> storvsc driver has a previous workaround that masks/blocks all errors
> reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
> the scan to then populate a full set of bogus LUN's on the target and
> then sends kernel spinning off into a death spiral doing block reads on
> the non-existent LUNs.
> 
> By setting the correct blacklist flags, the target with the DVD device
> is scanned with REPORTLUN and that works correctly.
> 
> Patch needs to go in current 4.11, it is safe but not necessary in older
> kernels.
> 
> Signed-off-by: Stephen Hemminger <sthem...@microsoft.com>
> Reviewed-by: K. Y. Srinivasan <k...@microsoft.com>
> Reviewed-by: Christoph Hellwig <h...@lst.de>
> Signed-off-by: Martin K. Petersen <martin.peter...@oracle.com>
>
> -Original Message-
> From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
> Sent: Monday, March 27, 2017 1:22 PM
> To: Long Li <lon...@microsoft.com>
> Cc: KY Srinivasan <k...@microsoft.com>; Martin K. Petersen 
> <martin.peter...@oracle.com>; Haiyang Zhang <haiya...@microsoft.com>; Stephen 
> Hemminger <sthem...@microsoft.com>; j...@linux.vnet.ibm.com; 
> de...@linuxdriverproject.org; linux-scsi <linux-s...@vger.kernel.org>; LKML 
> <linux-kernel@vger.kernel.org>; sta...@vger.kernel.org; Greg KH 
> <gre...@linuxfoundation.org>
> Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
> scsi: storvsc: properly set residual data length on errors
>
> Hi Long Li,
>
> A kernel bug report was opened against Ubuntu [0].  After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
>
> commit 40630f462824ee24bc00d692865c86c3828094e0
> Author: Long Li <lon...@microsoft.com>
> Date:   Wed Dec 14 18:46:03 2016 -0800
>
> scsi: storvsc: properly set residual data length on errors
>
>
> The regression was introduced in mainline as of v4.11-rc1.  It was also
> cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.
>
>
> This regression seems pretty severe since it's preventing virtual
> machines from booting.  It's affecting a couple of users so far.  I was
> hoping to get your feedback, since you are the patch author.  Do you
> think gathering any additional data will help diagnose this issue, or
> would it be best to submit a revert request?
>
>
> Thanks,
>
> Joe
>
>
> [0] http://pad.lv/1674635
>
>
Hi Stephen,


Thanks again for pointing out commit
f1c635b439a5c01776fe3a25b1e2dc546ea82e6f.  It does indeed fix the bug. 
I noticed the commit was not cc'd to stable.  Would it be possible to do
that?


Thanks,


Joe

RE: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-28 Thread Stephen Hemminger 
I decided not to send it to stable since problem was only observed on 4.11 but 
it is probably endemic to all GEN2 VM's

-Original Message-
From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
Sent: Tuesday, March 28, 2017 7:29 AM
To: Stephen Hemminger ; Long Li 
Cc: KY Srinivasan ; Martin K. Petersen 
; Haiyang Zhang ; 
j...@linux.vnet.ibm.com; de...@linuxdriverproject.org; linux-scsi 
; LKML ; 
sta...@vger.kernel.org; Greg KH 
Subject: Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
scsi: storvsc: properly set residual data length on errors

On 03/27/2017 06:14 PM, Stephen Hemminger wrote:
> Are you sure the real problem is not the one fixed by this commit?
>
> commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> Author: Stephen Hemminger 
> Date:   Tue Mar 7 09:15:53 2017 -0800
>
> scsi: storvsc: Workaround for virtual DVD SCSI version
> 
> Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
> version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
> 
> Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
> successfully with virtual DVD ROM device. What happens is that the SCSI
> scan process falls back to doing sequential probing by INQUIRY.  But the
> storvsc driver has a previous workaround that masks/blocks all errors
> reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
> the scan to then populate a full set of bogus LUN's on the target and
> then sends kernel spinning off into a death spiral doing block reads on
> the non-existent LUNs.
> 
> By setting the correct blacklist flags, the target with the DVD device
> is scanned with REPORTLUN and that works correctly.
> 
> Patch needs to go in current 4.11, it is safe but not necessary in older
> kernels.
> 
> Signed-off-by: Stephen Hemminger 
> Reviewed-by: K. Y. Srinivasan 
> Reviewed-by: Christoph Hellwig 
> Signed-off-by: Martin K. Petersen 
>
> -Original Message-
> From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
> Sent: Monday, March 27, 2017 1:22 PM
> To: Long Li 
> Cc: KY Srinivasan ; Martin K. Petersen 
> ; Haiyang Zhang ; Stephen 
> Hemminger ; j...@linux.vnet.ibm.com; 
> de...@linuxdriverproject.org; linux-scsi ; LKML 
> ; sta...@vger.kernel.org; Greg KH 
> 
> Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
> scsi: storvsc: properly set residual data length on errors
>
> Hi Long Li,
>
> A kernel bug report was opened against Ubuntu [0].  After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
>
> commit 40630f462824ee24bc00d692865c86c3828094e0
> Author: Long Li 
> Date:   Wed Dec 14 18:46:03 2016 -0800
>
> scsi: storvsc: properly set residual data length on errors
>
>
> The regression was introduced in mainline as of v4.11-rc1.  It was also
> cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.
>
>
> This regression seems pretty severe since it's preventing virtual
> machines from booting.  It's affecting a couple of users so far.  I was
> hoping to get your feedback, since you are the patch author.  Do you
> think gathering any additional data will help diagnose this issue, or
> would it be best to submit a revert request?
>
>
> Thanks,
>
> Joe
>
>
> [0] http://pad.lv/1674635
>
>
Hi Stephen,


Thanks again for pointing out commit
f1c635b439a5c01776fe3a25b1e2dc546ea82e6f.  It does indeed fix the bug. 
I noticed the commit was not cc'd to stable.  Would it be possible to do
that?


Thanks,


Joe

Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-28 Thread Joseph Salisbury 
On 03/27/2017 06:14 PM, Stephen Hemminger wrote:
> Are you sure the real problem is not the one fixed by this commit?
>
> commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> Author: Stephen Hemminger 
> Date:   Tue Mar 7 09:15:53 2017 -0800
>
> scsi: storvsc: Workaround for virtual DVD SCSI version
> 
> Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
> version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
> 
> Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
> successfully with virtual DVD ROM device. What happens is that the SCSI
> scan process falls back to doing sequential probing by INQUIRY.  But the
> storvsc driver has a previous workaround that masks/blocks all errors
> reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
> the scan to then populate a full set of bogus LUN's on the target and
> then sends kernel spinning off into a death spiral doing block reads on
> the non-existent LUNs.
> 
> By setting the correct blacklist flags, the target with the DVD device
> is scanned with REPORTLUN and that works correctly.
> 
> Patch needs to go in current 4.11, it is safe but not necessary in older
> kernels.
> 
> Signed-off-by: Stephen Hemminger 
> Reviewed-by: K. Y. Srinivasan 
> Reviewed-by: Christoph Hellwig 
> Signed-off-by: Martin K. Petersen 
>
> -Original Message-
> From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
> Sent: Monday, March 27, 2017 1:22 PM
> To: Long Li 
> Cc: KY Srinivasan ; Martin K. Petersen 
> ; Haiyang Zhang ; Stephen 
> Hemminger ; j...@linux.vnet.ibm.com; 
> de...@linuxdriverproject.org; linux-scsi ; LKML 
> ; sta...@vger.kernel.org; Greg KH 
> 
> Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
> scsi: storvsc: properly set residual data length on errors
>
> Hi Long Li,
>
> A kernel bug report was opened against Ubuntu [0].  After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
>
> commit 40630f462824ee24bc00d692865c86c3828094e0
> Author: Long Li 
> Date:   Wed Dec 14 18:46:03 2016 -0800
>
> scsi: storvsc: properly set residual data length on errors
>
>
> The regression was introduced in mainline as of v4.11-rc1.  It was also
> cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.
>
>
> This regression seems pretty severe since it's preventing virtual
> machines from booting.  It's affecting a couple of users so far.  I was
> hoping to get your feedback, since you are the patch author.  Do you
> think gathering any additional data will help diagnose this issue, or
> would it be best to submit a revert request?
>
>
> Thanks,
>
> Joe
>
>
> [0] http://pad.lv/1674635
>
>
Hi Stephen,


Thanks again for pointing out commit
f1c635b439a5c01776fe3a25b1e2dc546ea82e6f.  It does indeed fix the bug. 
I noticed the commit was not cc'd to stable.  Would it be possible to do
that?


Thanks,


Joe

Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-28 Thread Joseph Salisbury 
On 03/27/2017 06:14 PM, Stephen Hemminger wrote:
> Are you sure the real problem is not the one fixed by this commit?
>
> commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> Author: Stephen Hemminger 
> Date:   Tue Mar 7 09:15:53 2017 -0800
>
> scsi: storvsc: Workaround for virtual DVD SCSI version
> 
> Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
> version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
> 
> Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
> successfully with virtual DVD ROM device. What happens is that the SCSI
> scan process falls back to doing sequential probing by INQUIRY.  But the
> storvsc driver has a previous workaround that masks/blocks all errors
> reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
> the scan to then populate a full set of bogus LUN's on the target and
> then sends kernel spinning off into a death spiral doing block reads on
> the non-existent LUNs.
> 
> By setting the correct blacklist flags, the target with the DVD device
> is scanned with REPORTLUN and that works correctly.
> 
> Patch needs to go in current 4.11, it is safe but not necessary in older
> kernels.
> 
> Signed-off-by: Stephen Hemminger 
> Reviewed-by: K. Y. Srinivasan 
> Reviewed-by: Christoph Hellwig 
> Signed-off-by: Martin K. Petersen 
>
> -Original Message-
> From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
> Sent: Monday, March 27, 2017 1:22 PM
> To: Long Li 
> Cc: KY Srinivasan ; Martin K. Petersen 
> ; Haiyang Zhang ; Stephen 
> Hemminger ; j...@linux.vnet.ibm.com; 
> de...@linuxdriverproject.org; linux-scsi ; LKML 
> ; sta...@vger.kernel.org; Greg KH 
> 
> Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
> scsi: storvsc: properly set residual data length on errors
>
> Hi Long Li,
>
> A kernel bug report was opened against Ubuntu [0].  After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
>
> commit 40630f462824ee24bc00d692865c86c3828094e0
> Author: Long Li 
> Date:   Wed Dec 14 18:46:03 2016 -0800
>
> scsi: storvsc: properly set residual data length on errors
>
>
> The regression was introduced in mainline as of v4.11-rc1.  It was also
> cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.
>
>
> This regression seems pretty severe since it's preventing virtual
> machines from booting.  It's affecting a couple of users so far.  I was
> hoping to get your feedback, since you are the patch author.  Do you
> think gathering any additional data will help diagnose this issue, or
> would it be best to submit a revert request?
>
>
> Thanks,
>
> Joe
>
>
> [0] http://pad.lv/1674635
>
>
Hi Stephen,


Thanks again for pointing out commit
f1c635b439a5c01776fe3a25b1e2dc546ea82e6f.  It does indeed fix the bug. 
I noticed the commit was not cc'd to stable.  Would it be possible to do
that?


Thanks,


Joe

Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-27 Thread Joseph Salisbury 
On 03/27/2017 06:14 PM, Stephen Hemminger wrote:
> Are you sure the real problem is not the one fixed by this commit?
>
> commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> Author: Stephen Hemminger 
> Date:   Tue Mar 7 09:15:53 2017 -0800
>
> scsi: storvsc: Workaround for virtual DVD SCSI version
> 
> Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
> version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
> 
> Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
> successfully with virtual DVD ROM device. What happens is that the SCSI
> scan process falls back to doing sequential probing by INQUIRY.  But the
> storvsc driver has a previous workaround that masks/blocks all errors
> reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
> the scan to then populate a full set of bogus LUN's on the target and
> then sends kernel spinning off into a death spiral doing block reads on
> the non-existent LUNs.
> 
> By setting the correct blacklist flags, the target with the DVD device
> is scanned with REPORTLUN and that works correctly.
> 
> Patch needs to go in current 4.11, it is safe but not necessary in older
> kernels.
> 
> Signed-off-by: Stephen Hemminger 
> Reviewed-by: K. Y. Srinivasan 
> Reviewed-by: Christoph Hellwig 
> Signed-off-by: Martin K. Petersen 
>
> -Original Message-
> From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
> Sent: Monday, March 27, 2017 1:22 PM
> To: Long Li 
> Cc: KY Srinivasan ; Martin K. Petersen 
> ; Haiyang Zhang ; Stephen 
> Hemminger ; j...@linux.vnet.ibm.com; 
> de...@linuxdriverproject.org; linux-scsi ; LKML 
> ; sta...@vger.kernel.org; Greg KH 
> 
> Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
> scsi: storvsc: properly set residual data length on errors
>
> Hi Long Li,
>
> A kernel bug report was opened against Ubuntu [0].  After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
>
> commit 40630f462824ee24bc00d692865c86c3828094e0
> Author: Long Li 
> Date:   Wed Dec 14 18:46:03 2016 -0800
>
> scsi: storvsc: properly set residual data length on errors
>
>
> The regression was introduced in mainline as of v4.11-rc1.  It was also
> cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.
>
>
> This regression seems pretty severe since it's preventing virtual
> machines from booting.  It's affecting a couple of users so far.  I was
> hoping to get your feedback, since you are the patch author.  Do you
> think gathering any additional data will help diagnose this issue, or
> would it be best to submit a revert request?
>
>
> Thanks,
>
> Joe
>
>
> [0] http://pad.lv/1674635
>
>
Thanks for the pointer, Stephen.  I'll have this patch tested and
respond with the results.


Joe

Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-27 Thread Joseph Salisbury 
On 03/27/2017 06:14 PM, Stephen Hemminger wrote:
> Are you sure the real problem is not the one fixed by this commit?
>
> commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
> Author: Stephen Hemminger 
> Date:   Tue Mar 7 09:15:53 2017 -0800
>
> scsi: storvsc: Workaround for virtual DVD SCSI version
> 
> Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
> version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
> 
> Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
> successfully with virtual DVD ROM device. What happens is that the SCSI
> scan process falls back to doing sequential probing by INQUIRY.  But the
> storvsc driver has a previous workaround that masks/blocks all errors
> reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
> the scan to then populate a full set of bogus LUN's on the target and
> then sends kernel spinning off into a death spiral doing block reads on
> the non-existent LUNs.
> 
> By setting the correct blacklist flags, the target with the DVD device
> is scanned with REPORTLUN and that works correctly.
> 
> Patch needs to go in current 4.11, it is safe but not necessary in older
> kernels.
> 
> Signed-off-by: Stephen Hemminger 
> Reviewed-by: K. Y. Srinivasan 
> Reviewed-by: Christoph Hellwig 
> Signed-off-by: Martin K. Petersen 
>
> -Original Message-
> From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
> Sent: Monday, March 27, 2017 1:22 PM
> To: Long Li 
> Cc: KY Srinivasan ; Martin K. Petersen 
> ; Haiyang Zhang ; Stephen 
> Hemminger ; j...@linux.vnet.ibm.com; 
> de...@linuxdriverproject.org; linux-scsi ; LKML 
> ; sta...@vger.kernel.org; Greg KH 
> 
> Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
> scsi: storvsc: properly set residual data length on errors
>
> Hi Long Li,
>
> A kernel bug report was opened against Ubuntu [0].  After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
>
> commit 40630f462824ee24bc00d692865c86c3828094e0
> Author: Long Li 
> Date:   Wed Dec 14 18:46:03 2016 -0800
>
> scsi: storvsc: properly set residual data length on errors
>
>
> The regression was introduced in mainline as of v4.11-rc1.  It was also
> cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.
>
>
> This regression seems pretty severe since it's preventing virtual
> machines from booting.  It's affecting a couple of users so far.  I was
> hoping to get your feedback, since you are the patch author.  Do you
> think gathering any additional data will help diagnose this issue, or
> would it be best to submit a revert request?
>
>
> Thanks,
>
> Joe
>
>
> [0] http://pad.lv/1674635
>
>
Thanks for the pointer, Stephen.  I'll have this patch tested and
respond with the results.


Joe

RE: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-27 Thread Stephen Hemminger 
Are you sure the real problem is not the one fixed by this commit?

commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
Author: Stephen Hemminger 
Date:   Tue Mar 7 09:15:53 2017 -0800

scsi: storvsc: Workaround for virtual DVD SCSI version

Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.

Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
successfully with virtual DVD ROM device. What happens is that the SCSI
scan process falls back to doing sequential probing by INQUIRY.  But the
storvsc driver has a previous workaround that masks/blocks all errors
reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
the scan to then populate a full set of bogus LUN's on the target and
then sends kernel spinning off into a death spiral doing block reads on
the non-existent LUNs.

By setting the correct blacklist flags, the target with the DVD device
is scanned with REPORTLUN and that works correctly.

Patch needs to go in current 4.11, it is safe but not necessary in older
kernels.

Signed-off-by: Stephen Hemminger 
Reviewed-by: K. Y. Srinivasan 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Martin K. Petersen 

-Original Message-
From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
Sent: Monday, March 27, 2017 1:22 PM
To: Long Li 
Cc: KY Srinivasan ; Martin K. Petersen 
; Haiyang Zhang ; Stephen 
Hemminger ; j...@linux.vnet.ibm.com; 
de...@linuxdriverproject.org; linux-scsi ; LKML 
; sta...@vger.kernel.org; Greg KH 

Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
scsi: storvsc: properly set residual data length on errors

Hi Long Li,

A kernel bug report was opened against Ubuntu [0].  After a kernel
bisect, it was found that reverting the following commit resolved this bug:

commit 40630f462824ee24bc00d692865c86c3828094e0
Author: Long Li 
Date:   Wed Dec 14 18:46:03 2016 -0800

scsi: storvsc: properly set residual data length on errors


The regression was introduced in mainline as of v4.11-rc1.  It was also
cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.


This regression seems pretty severe since it's preventing virtual
machines from booting.  It's affecting a couple of users so far.  I was
hoping to get your feedback, since you are the patch author.  Do you
think gathering any additional data will help diagnose this issue, or
would it be best to submit a revert request?


Thanks,

Joe


[0] http://pad.lv/1674635

RE: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors

2017-03-27 Thread Stephen Hemminger 
Are you sure the real problem is not the one fixed by this commit?

commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f
Author: Stephen Hemminger 
Date:   Tue Mar 7 09:15:53 2017 -0800

scsi: storvsc: Workaround for virtual DVD SCSI version

Hyper-V host emulation of SCSI for virtual DVD device reports SCSI
version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.

Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11
successfully with virtual DVD ROM device. What happens is that the SCSI
scan process falls back to doing sequential probing by INQUIRY.  But the
storvsc driver has a previous workaround that masks/blocks all errors
reports from INQUIRY (or MODE_SENSE) commands.  This workaround causes
the scan to then populate a full set of bogus LUN's on the target and
then sends kernel spinning off into a death spiral doing block reads on
the non-existent LUNs.

By setting the correct blacklist flags, the target with the DVD device
is scanned with REPORTLUN and that works correctly.

Patch needs to go in current 4.11, it is safe but not necessary in older
kernels.

Signed-off-by: Stephen Hemminger 
Reviewed-by: K. Y. Srinivasan 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Martin K. Petersen 

-Original Message-
From: Joseph Salisbury [mailto:joseph.salisb...@canonical.com] 
Sent: Monday, March 27, 2017 1:22 PM
To: Long Li 
Cc: KY Srinivasan ; Martin K. Petersen 
; Haiyang Zhang ; Stephen 
Hemminger ; j...@linux.vnet.ibm.com; 
de...@linuxdriverproject.org; linux-scsi ; LKML 
; sta...@vger.kernel.org; Greg KH 

Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] 
scsi: storvsc: properly set residual data length on errors

Hi Long Li,

A kernel bug report was opened against Ubuntu [0].  After a kernel
bisect, it was found that reverting the following commit resolved this bug:

commit 40630f462824ee24bc00d692865c86c3828094e0
Author: Long Li 
Date:   Wed Dec 14 18:46:03 2016 -0800

scsi: storvsc: properly set residual data length on errors


The regression was introduced in mainline as of v4.11-rc1.  It was also
cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y.


This regression seems pretty severe since it's preventing virtual
machines from booting.  It's affecting a couple of users so far.  I was
hoping to get your feedback, since you are the patch author.  Do you
think gathering any additional data will help diagnose this issue, or
would it be best to submit a revert request?


Thanks,

Joe


[0] http://pad.lv/1674635