flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Mike Snitzer]

5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
__generic_fsdax_supported()") switched from pr_debug() to pr_info().

The justification in the commit header is really inadequate.  If there
is a problem that you need to drill in on, repeat the testing after
enabling the dynamic debugging.

Otherwise, now all DM devices that aren't layered on DAX capable devices
spew really confusing noise to users when they simply activate their
non-DAX DM devices:

[66567.129798] dm-6: error: dax access failed (-5)
[66567.134400] dm-6: error: dax access failed (-5)
[66567.139152] dm-6: error: dax access failed (-5)
[66567.314546] dm-2: error: dax access failed (-95)
[66567.319380] dm-2: error: dax access failed (-95)
[66567.324254] dm-2: error: dax access failed (-95)
[66567.479025] dm-2: error: dax access failed (-95)
[66567.483713] dm-2: error: dax access failed (-95)
[66567.488722] dm-2: error: dax access failed (-95)
[66567.494061] dm-2: error: dax access failed (-95)
[66567.498823] dm-2: error: dax access failed (-95)
[66567.503693] dm-2: error: dax access failed (-95)

commit 231609785cbfb must be reverted.

Please advise, thanks.
Mike
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 00:04, Mike Snitzer wrote:
> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
> 
> The justification in the commit header is really inadequate.  If there
> is a problem that you need to drill in on, repeat the testing after
> enabling the dynamic debugging.
> 
> Otherwise, now all DM devices that aren't layered on DAX capable devices
> spew really confusing noise to users when they simply activate their
> non-DAX DM devices:
> 
> [66567.129798] dm-6: error: dax access failed (-5)
> [66567.134400] dm-6: error: dax access failed (-5)
> [66567.139152] dm-6: error: dax access failed (-5)
> [66567.314546] dm-2: error: dax access failed (-95)
> [66567.319380] dm-2: error: dax access failed (-95)
> [66567.324254] dm-2: error: dax access failed (-95)
> [66567.479025] dm-2: error: dax access failed (-95)
> [66567.483713] dm-2: error: dax access failed (-95)
> [66567.488722] dm-2: error: dax access failed (-95)
> [66567.494061] dm-2: error: dax access failed (-95)
> [66567.498823] dm-2: error: dax access failed (-95)
> [66567.503693] dm-2: error: dax access failed (-95)
> 
> commit 231609785cbfb must be reverted.
> 
> Please advise, thanks.

Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
error message for non-persistent memory block device

It fixes the issue, but no response for now. Maybe we should take this fix.

Thanks.

Coly Li

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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Mike Snitzer]

On Wed, Sep 02 2020 at 12:40pm -0400,
Coly Li <colyli@suse.de> wrote:

> On 2020/9/3 00:04, Mike Snitzer wrote:
> > 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
> > __generic_fsdax_supported()") switched from pr_debug() to pr_info().
> > 
> > The justification in the commit header is really inadequate.  If there
> > is a problem that you need to drill in on, repeat the testing after
> > enabling the dynamic debugging.
> > 
> > Otherwise, now all DM devices that aren't layered on DAX capable devices
> > spew really confusing noise to users when they simply activate their
> > non-DAX DM devices:
> > 
> > [66567.129798] dm-6: error: dax access failed (-5)
> > [66567.134400] dm-6: error: dax access failed (-5)
> > [66567.139152] dm-6: error: dax access failed (-5)
> > [66567.314546] dm-2: error: dax access failed (-95)
> > [66567.319380] dm-2: error: dax access failed (-95)
> > [66567.324254] dm-2: error: dax access failed (-95)
> > [66567.479025] dm-2: error: dax access failed (-95)
> > [66567.483713] dm-2: error: dax access failed (-95)
> > [66567.488722] dm-2: error: dax access failed (-95)
> > [66567.494061] dm-2: error: dax access failed (-95)
> > [66567.498823] dm-2: error: dax access failed (-95)
> > [66567.503693] dm-2: error: dax access failed (-95)
> > 
> > commit 231609785cbfb must be reverted.
> > 
> > Please advise, thanks.
> 
> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
> error message for non-persistent memory block device
> 
> It fixes the issue, but no response for now. Maybe we should take this fix.

OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
("dax: do not print error message for non-persistent memory block
device")

Thanks for the info.
Mike
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 00:44, Mike Snitzer wrote:
> On Wed, Sep 02 2020 at 12:40pm -0400,
> Coly Li <colyli@suse.de> wrote:
> 
>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>
>>> The justification in the commit header is really inadequate.  If there
>>> is a problem that you need to drill in on, repeat the testing after
>>> enabling the dynamic debugging.
>>>
>>> Otherwise, now all DM devices that aren't layered on DAX capable devices
>>> spew really confusing noise to users when they simply activate their
>>> non-DAX DM devices:
>>>
>>> [66567.129798] dm-6: error: dax access failed (-5)
>>> [66567.134400] dm-6: error: dax access failed (-5)
>>> [66567.139152] dm-6: error: dax access failed (-5)
>>> [66567.314546] dm-2: error: dax access failed (-95)
>>> [66567.319380] dm-2: error: dax access failed (-95)
>>> [66567.324254] dm-2: error: dax access failed (-95)
>>> [66567.479025] dm-2: error: dax access failed (-95)
>>> [66567.483713] dm-2: error: dax access failed (-95)
>>> [66567.488722] dm-2: error: dax access failed (-95)
>>> [66567.494061] dm-2: error: dax access failed (-95)
>>> [66567.498823] dm-2: error: dax access failed (-95)
>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>
>>> commit 231609785cbfb must be reverted.
>>>
>>> Please advise, thanks.
>>
>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
>> error message for non-persistent memory block device
>>
>> It fixes the issue, but no response for now. Maybe we should take this fix.
> 
> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
> ("dax: do not print error message for non-persistent memory block
> device")

Thanks for informing me this patch is merged, I am going to update my
local one :-)

Coly Li
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Mike Snitzer]

On Wed, Sep 02 2020 at 12:46pm -0400,
Coly Li <colyli@suse.de> wrote:

> On 2020/9/3 00:44, Mike Snitzer wrote:
> > On Wed, Sep 02 2020 at 12:40pm -0400,
> > Coly Li <colyli@suse.de> wrote:
> > 
> >> On 2020/9/3 00:04, Mike Snitzer wrote:
> >>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
> >>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
> >>>
> >>> The justification in the commit header is really inadequate.  If there
> >>> is a problem that you need to drill in on, repeat the testing after
> >>> enabling the dynamic debugging.
> >>>
> >>> Otherwise, now all DM devices that aren't layered on DAX capable devices
> >>> spew really confusing noise to users when they simply activate their
> >>> non-DAX DM devices:
> >>>
> >>> [66567.129798] dm-6: error: dax access failed (-5)
> >>> [66567.134400] dm-6: error: dax access failed (-5)
> >>> [66567.139152] dm-6: error: dax access failed (-5)
> >>> [66567.314546] dm-2: error: dax access failed (-95)
> >>> [66567.319380] dm-2: error: dax access failed (-95)
> >>> [66567.324254] dm-2: error: dax access failed (-95)
> >>> [66567.479025] dm-2: error: dax access failed (-95)
> >>> [66567.483713] dm-2: error: dax access failed (-95)
> >>> [66567.488722] dm-2: error: dax access failed (-95)
> >>> [66567.494061] dm-2: error: dax access failed (-95)
> >>> [66567.498823] dm-2: error: dax access failed (-95)
> >>> [66567.503693] dm-2: error: dax access failed (-95)
> >>>
> >>> commit 231609785cbfb must be reverted.
> >>>
> >>> Please advise, thanks.
> >>
> >> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
> >> error message for non-persistent memory block device
> >>
> >> It fixes the issue, but no response for now. Maybe we should take this fix.
> > 
> > OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
> > ("dax: do not print error message for non-persistent memory block
> > device")
> 
> Thanks for informing me this patch is merged, I am going to update my
> local one :-)

So the thing is I'm running v5.9-rc3 (which includes this commit) but
I'm still seeing all these warnings when I run the lvm2 testsuite.  The
reason _seems_ to be because the lvm2 testsuite uses brd devices for
test devices.  So there is something about the brd device that shows
commit c2affe920b0e066 isn't enough :(

Mike
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 00:51, Mike Snitzer wrote:
> On Wed, Sep 02 2020 at 12:46pm -0400,
> Coly Li <colyli@suse.de> wrote:
> 
>> On 2020/9/3 00:44, Mike Snitzer wrote:
>>> On Wed, Sep 02 2020 at 12:40pm -0400,
>>> Coly Li <colyli@suse.de> wrote:
>>>
>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>>>
>>>>> The justification in the commit header is really inadequate.  If there
>>>>> is a problem that you need to drill in on, repeat the testing after
>>>>> enabling the dynamic debugging.
>>>>>
>>>>> Otherwise, now all DM devices that aren't layered on DAX capable devices
>>>>> spew really confusing noise to users when they simply activate their
>>>>> non-DAX DM devices:
>>>>>
>>>>> [66567.129798] dm-6: error: dax access failed (-5)
>>>>> [66567.134400] dm-6: error: dax access failed (-5)
>>>>> [66567.139152] dm-6: error: dax access failed (-5)
>>>>> [66567.314546] dm-2: error: dax access failed (-95)
>>>>> [66567.319380] dm-2: error: dax access failed (-95)
>>>>> [66567.324254] dm-2: error: dax access failed (-95)
>>>>> [66567.479025] dm-2: error: dax access failed (-95)
>>>>> [66567.483713] dm-2: error: dax access failed (-95)
>>>>> [66567.488722] dm-2: error: dax access failed (-95)
>>>>> [66567.494061] dm-2: error: dax access failed (-95)
>>>>> [66567.498823] dm-2: error: dax access failed (-95)
>>>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>>>
>>>>> commit 231609785cbfb must be reverted.
>>>>>
>>>>> Please advise, thanks.
>>>>
>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
>>>> error message for non-persistent memory block device
>>>>
>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>>
>>> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
>>> ("dax: do not print error message for non-persistent memory block
>>> device")
>>
>> Thanks for informing me this patch is merged, I am going to update my
>> local one :-)
> 
> So the thing is I'm running v5.9-rc3 (which includes this commit) but
> I'm still seeing all these warnings when I run the lvm2 testsuite.  The
> reason _seems_ to be because the lvm2 testsuite uses brd devices for
> test devices.  So there is something about the brd device that shows
> commit c2affe920b0e066 isn't enough :(

Let me take a look. Thanks for reminding me.

Coly Li
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

[-- Attachment #1: Type: text/plain, Size: 2780 bytes --]

On 2020/9/3 00:51, Mike Snitzer wrote:
> On Wed, Sep 02 2020 at 12:46pm -0400,
> Coly Li <colyli@suse.de> wrote:
> 
>> On 2020/9/3 00:44, Mike Snitzer wrote:
>>> On Wed, Sep 02 2020 at 12:40pm -0400,
>>> Coly Li <colyli@suse.de> wrote:
>>>
>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>>>
>>>>> The justification in the commit header is really inadequate.  If there
>>>>> is a problem that you need to drill in on, repeat the testing after
>>>>> enabling the dynamic debugging.
>>>>>
>>>>> Otherwise, now all DM devices that aren't layered on DAX capable devices
>>>>> spew really confusing noise to users when they simply activate their
>>>>> non-DAX DM devices:
>>>>>
>>>>> [66567.129798] dm-6: error: dax access failed (-5)
>>>>> [66567.134400] dm-6: error: dax access failed (-5)
>>>>> [66567.139152] dm-6: error: dax access failed (-5)
>>>>> [66567.314546] dm-2: error: dax access failed (-95)
>>>>> [66567.319380] dm-2: error: dax access failed (-95)
>>>>> [66567.324254] dm-2: error: dax access failed (-95)
>>>>> [66567.479025] dm-2: error: dax access failed (-95)
>>>>> [66567.483713] dm-2: error: dax access failed (-95)
>>>>> [66567.488722] dm-2: error: dax access failed (-95)
>>>>> [66567.494061] dm-2: error: dax access failed (-95)
>>>>> [66567.498823] dm-2: error: dax access failed (-95)
>>>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>>>
>>>>> commit 231609785cbfb must be reverted.
>>>>>
>>>>> Please advise, thanks.
>>>>
>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
>>>> error message for non-persistent memory block device
>>>>
>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>>
>>> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
>>> ("dax: do not print error message for non-persistent memory block
>>> device")
>>
>> Thanks for informing me this patch is merged, I am going to update my
>> local one :-)
> 
> So the thing is I'm running v5.9-rc3 (which includes this commit) but
> I'm still seeing all these warnings when I run the lvm2 testsuite.  The
> reason _seems_ to be because the lvm2 testsuite uses brd devices for
> test devices.  So there is something about the brd device that shows
> commit c2affe920b0e066 isn't enough :(

Could you please apply and test this attached patch based on v5.9-rc3 ?

It seems the pointer dax_dev of __generic_fsdax_supported() parameter is
not initialized (IMHO this is not a dm bug), therefore the && should be
|| to check the dax support state.

Also I add two pr_info() to print the variables value, let's see whether
my guess makes sense.

Thanks.

Coly Li


[-- Attachment #2: 0001-dax-fix-for-do-not-print-error-message-for-non-persi.patch --]
[-- Type: text/plain, Size: 1183 bytes --]

From 3714b91362669c4d3e281acfe197e922a1dd1b4a Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Thu, 3 Sep 2020 12:25:13 +0800
Subject: [PATCH] dax: fix for do not print error message for non-persistent
 memory block device

When calling __generic_fsdax_supported(), a dax-unsupported device may
not have dax_dev as NULL. Therefore even dax_dev is not NULL, it is
still necessary to call bdev_dax_supported() to check whether the device
supports dax.

Signed-off-by: Coly Li <colyli@suse.de>
---
 drivers/dax/super.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 32642634c1bb..a5bdfca0529a 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -100,7 +100,9 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 		return false;
 	}
 
-	if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
+	pr_info("dax_dev: %p\n", dax_dev);
+	pr_info("bdev_dax_supported(): %d\n", bdev_dax_supported(bdev, blocksize));
+	if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
 		pr_debug("%s: error: dax unsupported by block device\n",
 				bdevname(bdev, buf));
 		return false;
-- 
2.26.2


[-- Attachment #3: Type: text/plain, Size: 167 bytes --]

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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

[-- Attachment #1: Type: text/plain, Size: 2821 bytes --]

On 2020/9/3 00:51, Mike Snitzer wrote:
> On Wed, Sep 02 2020 at 12:46pm -0400,
> Coly Li <colyli@suse.de> wrote:
> 
>> On 2020/9/3 00:44, Mike Snitzer wrote:
>>> On Wed, Sep 02 2020 at 12:40pm -0400,
>>> Coly Li <colyli@suse.de> wrote:
>>>
>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>>>
>>>>> The justification in the commit header is really inadequate.  If there
>>>>> is a problem that you need to drill in on, repeat the testing after
>>>>> enabling the dynamic debugging.
>>>>>
>>>>> Otherwise, now all DM devices that aren't layered on DAX capable devices
>>>>> spew really confusing noise to users when they simply activate their
>>>>> non-DAX DM devices:
>>>>>
>>>>> [66567.129798] dm-6: error: dax access failed (-5)
>>>>> [66567.134400] dm-6: error: dax access failed (-5)
>>>>> [66567.139152] dm-6: error: dax access failed (-5)
>>>>> [66567.314546] dm-2: error: dax access failed (-95)
>>>>> [66567.319380] dm-2: error: dax access failed (-95)
>>>>> [66567.324254] dm-2: error: dax access failed (-95)
>>>>> [66567.479025] dm-2: error: dax access failed (-95)
>>>>> [66567.483713] dm-2: error: dax access failed (-95)
>>>>> [66567.488722] dm-2: error: dax access failed (-95)
>>>>> [66567.494061] dm-2: error: dax access failed (-95)
>>>>> [66567.498823] dm-2: error: dax access failed (-95)
>>>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>>>
>>>>> commit 231609785cbfb must be reverted.
>>>>>
>>>>> Please advise, thanks.
>>>>
>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
>>>> error message for non-persistent memory block device
>>>>
>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>>
>>> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
>>> ("dax: do not print error message for non-persistent memory block
>>> device")
>>
>> Thanks for informing me this patch is merged, I am going to update my
>> local one :-)
> 
> So the thing is I'm running v5.9-rc3 (which includes this commit) but
> I'm still seeing all these warnings when I run the lvm2 testsuite.  The
> reason _seems_ to be because the lvm2 testsuite uses brd devices for
> test devices.  So there is something about the brd device that shows
> commit c2affe920b0e066 isn't enough :(

[Resend and CC Adrian Huang]

Hi Mike,

Could you please apply and test this attached patch based on v5.9-rc3 ?

It seems the pointer dax_dev of __generic_fsdax_supported() parameter is
not initialized (IMHO this is not a dm bug), therefore the && should be
|| to check the dax support state.

Also I add two pr_info() to print the variables value, let's see whether
my guess makes sense.

Thanks.

Coly Li



[-- Attachment #2: 0001-dax-fix-for-do-not-print-error-message-for-non-persi.patch --]
[-- Type: text/plain, Size: 1183 bytes --]

From 3714b91362669c4d3e281acfe197e922a1dd1b4a Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Thu, 3 Sep 2020 12:25:13 +0800
Subject: [PATCH] dax: fix for do not print error message for non-persistent
 memory block device

When calling __generic_fsdax_supported(), a dax-unsupported device may
not have dax_dev as NULL. Therefore even dax_dev is not NULL, it is
still necessary to call bdev_dax_supported() to check whether the device
supports dax.

Signed-off-by: Coly Li <colyli@suse.de>
---
 drivers/dax/super.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 32642634c1bb..a5bdfca0529a 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -100,7 +100,9 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 		return false;
 	}
 
-	if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
+	pr_info("dax_dev: %p\n", dax_dev);
+	pr_info("bdev_dax_supported(): %d\n", bdev_dax_supported(bdev, blocksize));
+	if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
 		pr_debug("%s: error: dax unsupported by block device\n",
 				bdevname(bdev, buf));
 		return false;
-- 
2.26.2


[-- Attachment #3: Type: text/plain, Size: 167 bytes --]

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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 13:20, Coly Li wrote:
> On 2020/9/3 00:51, Mike Snitzer wrote:
>> On Wed, Sep 02 2020 at 12:46pm -0400,
>> Coly Li <colyli@suse.de> wrote:
>>
>>> On 2020/9/3 00:44, Mike Snitzer wrote:
>>>> On Wed, Sep 02 2020 at 12:40pm -0400,
>>>> Coly Li <colyli@suse.de> wrote:
>>>>
>>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
>>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>>>>
>>>>>> The justification in the commit header is really inadequate.  If there
>>>>>> is a problem that you need to drill in on, repeat the testing after
>>>>>> enabling the dynamic debugging.
>>>>>>
>>>>>> Otherwise, now all DM devices that aren't layered on DAX capable devices
>>>>>> spew really confusing noise to users when they simply activate their
>>>>>> non-DAX DM devices:
>>>>>>
>>>>>> [66567.129798] dm-6: error: dax access failed (-5)
>>>>>> [66567.134400] dm-6: error: dax access failed (-5)
>>>>>> [66567.139152] dm-6: error: dax access failed (-5)
>>>>>> [66567.314546] dm-2: error: dax access failed (-95)
>>>>>> [66567.319380] dm-2: error: dax access failed (-95)
>>>>>> [66567.324254] dm-2: error: dax access failed (-95)
>>>>>> [66567.479025] dm-2: error: dax access failed (-95)
>>>>>> [66567.483713] dm-2: error: dax access failed (-95)
>>>>>> [66567.488722] dm-2: error: dax access failed (-95)
>>>>>> [66567.494061] dm-2: error: dax access failed (-95)
>>>>>> [66567.498823] dm-2: error: dax access failed (-95)
>>>>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>>>>
>>>>>> commit 231609785cbfb must be reverted.
>>>>>>
>>>>>> Please advise, thanks.
>>>>>
>>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
>>>>> error message for non-persistent memory block device
>>>>>
>>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>>>
>>>> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
>>>> ("dax: do not print error message for non-persistent memory block
>>>> device")
>>>
>>> Thanks for informing me this patch is merged, I am going to update my
>>> local one :-)
>>
>> So the thing is I'm running v5.9-rc3 (which includes this commit) but
>> I'm still seeing all these warnings when I run the lvm2 testsuite.  The
>> reason _seems_ to be because the lvm2 testsuite uses brd devices for
>> test devices.  So there is something about the brd device that shows
>> commit c2affe920b0e066 isn't enough :(
> 
> [Resend and CC Adrian Huang]
> 
> Hi Mike,
> 
> Could you please apply and test this attached patch based on v5.9-rc3 ?
> 
> It seems the pointer dax_dev of __generic_fsdax_supported() parameter is
> not initialized (IMHO this is not a dm bug), therefore the && should be
> || to check the dax support state.
> 
> Also I add two pr_info() to print the variables value, let's see whether
> my guess makes sense.

Also I suggest some kind of change like this in drivers/md/dm.c,

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index fb0255d25e4b..566d8208df47 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -818,6 +818,8 @@ int dm_get_table_device(struct mapped_device *md,
dev_t dev, fmode_t mode,
                        return -ENOMEM;
                }

+               memset(td, 0, sizeof(struct table_device));
+
                td->dm_dev.mode = mode;
                td->dm_dev.bdev = NULL;


The above change may make sure *dax_dev sent into
__generic_fsdax_supported() is always NULL if the target does not
support DAX. But IMHO this is not 100% necessary, it just make
__generic_fsdax_supported() return false faster by the following change
in previous attached patch,

 -       if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
 +       if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {

I am not very familiar with dm code, CMIIW, just for your information.

Coly Li
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RE: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Adrian Huang12]

> -----Original Message-----
> From: Coly Li <colyli@suse.de>
> Sent: Thursday, September 3, 2020 4:37 PM
> To: Mike Snitzer <snitzer@redhat.com>
> Cc: Jan Kara <jack@suse.com>; Ira Weiny <ira.weiny@intel.com>; Pankaj Gupta
> <pankaj.gupta.linux@gmail.com>; Vishal Verma <vishal.l.verma@intel.com>;
> linux-nvdimm@lists.01.org; Adrian Huang12 <ahuang12@lenovo.com>
> Subject: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9
> commit 231609785cbfb
> 
> On 2020/9/3 13:20, Coly Li wrote:
> > On 2020/9/3 00:51, Mike Snitzer wrote:
> >> On Wed, Sep 02 2020 at 12:46pm -0400, Coly Li <colyli@suse.de> wrote:
> >>
> >>> On 2020/9/3 00:44, Mike Snitzer wrote:
> >>>> On Wed, Sep 02 2020 at 12:40pm -0400, Coly Li <colyli@suse.de>
> >>>> wrote:
> >>>>
> >>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
> >>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info()
> >>>>>> in
> >>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
> >>>>>>
> >>>>>> The justification in the commit header is really inadequate.  If
> >>>>>> there is a problem that you need to drill in on, repeat the
> >>>>>> testing after enabling the dynamic debugging.
> >>>>>>
> >>>>>> Otherwise, now all DM devices that aren't layered on DAX capable
> >>>>>> devices spew really confusing noise to users when they simply
> >>>>>> activate their non-DAX DM devices:
> >>>>>>
> >>>>>> [66567.129798] dm-6: error: dax access failed (-5) [66567.134400]
> >>>>>> dm-6: error: dax access failed (-5) [66567.139152] dm-6: error:
> >>>>>> dax access failed (-5) [66567.314546] dm-2: error: dax access
> >>>>>> failed (-95) [66567.319380] dm-2: error: dax access failed (-95)
> >>>>>> [66567.324254] dm-2: error: dax access failed (-95)
> >>>>>> [66567.479025] dm-2: error: dax access failed (-95)
> >>>>>> [66567.483713] dm-2: error: dax access failed (-95)
> >>>>>> [66567.488722] dm-2: error: dax access failed (-95)
> >>>>>> [66567.494061] dm-2: error: dax access failed (-95)
> >>>>>> [66567.498823] dm-2: error: dax access failed (-95)
> >>>>>> [66567.503693] dm-2: error: dax access failed (-95)
> >>>>>>
> >>>>>> commit 231609785cbfb must be reverted.
> >>>>>>
> >>>>>> Please advise, thanks.
> >>>>>
> >>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not
> >>>>> print error message for non-persistent memory block device
> >>>>>
> >>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
> >>>>
> >>>> OK, yes sounds like it.  It was merged and is commit
> >>>> c2affe920b0e066
> >>>> ("dax: do not print error message for non-persistent memory block
> >>>> device")
> >>>
> >>> Thanks for informing me this patch is merged, I am going to update
> >>> my local one :-)
> >>
> >> So the thing is I'm running v5.9-rc3 (which includes this commit) but
> >> I'm still seeing all these warnings when I run the lvm2 testsuite.
> >> The reason _seems_ to be because the lvm2 testsuite uses brd devices
> >> for test devices.  So there is something about the brd device that
> >> shows commit c2affe920b0e066 isn't enough :(
> >
> > [Resend and CC Adrian Huang]
> >
> > Hi Mike,
> >
> > Could you please apply and test this attached patch based on v5.9-rc3 ?
> >
> > It seems the pointer dax_dev of __generic_fsdax_supported() parameter
> > is not initialized (IMHO this is not a dm bug), therefore the &&
> > should be
> > || to check the dax support state.
> >
> > Also I add two pr_info() to print the variables value, let's see
> > whether my guess makes sense.
> 
> Also I suggest some kind of change like this in drivers/md/dm.c,
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c index
> fb0255d25e4b..566d8208df47 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -818,6 +818,8 @@ int dm_get_table_device(struct mapped_device *md,
> dev_t dev, fmode_t mode,
>                         return -ENOMEM;
>                 }
> 
> +               memset(td, 0, sizeof(struct table_device));
> +

This does not help. See the following log.

-----------------
# lvm2-testsuite --only activate-minor
.......
[ 0:00] #activate-minor.sh:22+ aux prepare_vg 2
[ 0:00] ## preparing ramdisk device...ok (/dev/ram0)
[ 0:01] 6,3160,150710756,-;brd: module loaded
[ 0:01] ## preparing 2 devices...ok
[ 0:01] 6,3161,150730864,-;dax_dev: 0000000000000000
[ 0:01] 6,3162,150730866,-;bdev_dax_supported(): 0
[ 0:01] 6,3163,150730903,-;dax_dev: 0000000000000000
[ 0:01] 6,3164,150730905,-;bdev_dax_supported(): 0
[ 0:01] 6,3165,150731019,-;dax_dev: 0000000000000000
[ 0:01] 6,3166,150731020,-;bdev_dax_supported(): 0
[ 0:01] 6,3167,150731512,-;dax_dev: 0000000000000000
[ 0:01] 6,3168,150731514,-;bdev_dax_supported(): 0
[ 0:01] 6,3169,150731525,-;dax_dev: 0000000000000000
[ 0:01] 6,3170,150731525,-;bdev_dax_supported(): 0
[ 0:01] 6,3171,150731656,-;dax_dev: 0000000000000000
[ 0:01] 6,3172,150731657,-;bdev_dax_supported(): 0
.......
[ 0:01] lvchange $vg/foo -a y
[ 0:01] #activate-minor.sh:25+ lvchange LVMTEST12302vg/foo -a y
[ 0:01]   /tmp/LVMTEST12302.W0HGxyzxst/dev/mapper/LVMTEST12302vg-foo not set up by udev: Falling back to direct node creation.
[ 0:01] 6,3173,150927070,-;dax_dev: 00000000f0a5865d
[ 0:01] 6,3174,150927072,-;bdev_dax_supported(): 0
[ 0:01] 6,3175,150927081,-;dax_dev: 00000000f0a5865d
[ 0:01] 6,3176,150927082,-;bdev_dax_supported(): 0
[ 0:01] 6,3177,150927241,-;dax_dev: 00000000f0a5865d
[ 0:01] 6,3178,150927242,-;bdev_dax_supported(): 0
----------------

>                 td->dm_dev.mode = mode;
>                 td->dm_dev.bdev = NULL;
> 
> 
> The above change may make sure *dax_dev sent into
> __generic_fsdax_supported() is always NULL if the target does not support DAX.
> But IMHO this is not 100% necessary, it just make
> __generic_fsdax_supported() return false faster by the following change in
> previous attached patch,
> 
>  -       if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
>  +       if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
> 
> I am not very familiar with dm code, CMIIW, just for your information.
> 
> Coly Li

-- Adrian
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Re: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 19:24, Adrian Huang12 wrote:
> 
>> -----Original Message-----
>> From: Coly Li <colyli@suse.de>
>> Sent: Thursday, September 3, 2020 4:37 PM
>> To: Mike Snitzer <snitzer@redhat.com>
>> Cc: Jan Kara <jack@suse.com>; Ira Weiny <ira.weiny@intel.com>; Pankaj Gupta
>> <pankaj.gupta.linux@gmail.com>; Vishal Verma <vishal.l.verma@intel.com>;
>> linux-nvdimm@lists.01.org; Adrian Huang12 <ahuang12@lenovo.com>
>> Subject: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9
>> commit 231609785cbfb
>>
>> On 2020/9/3 13:20, Coly Li wrote:
>>> On 2020/9/3 00:51, Mike Snitzer wrote:
>>>> On Wed, Sep 02 2020 at 12:46pm -0400, Coly Li <colyli@suse.de> wrote:
>>>>
>>>>> On 2020/9/3 00:44, Mike Snitzer wrote:
>>>>>> On Wed, Sep 02 2020 at 12:40pm -0400, Coly Li <colyli@suse.de>
>>>>>> wrote:
>>>>>>
>>>>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>>>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info()
>>>>>>>> in
>>>>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>>>>>>
>>>>>>>> The justification in the commit header is really inadequate.  If
>>>>>>>> there is a problem that you need to drill in on, repeat the
>>>>>>>> testing after enabling the dynamic debugging.
>>>>>>>>
>>>>>>>> Otherwise, now all DM devices that aren't layered on DAX capable
>>>>>>>> devices spew really confusing noise to users when they simply
>>>>>>>> activate their non-DAX DM devices:
>>>>>>>>
>>>>>>>> [66567.129798] dm-6: error: dax access failed (-5) [66567.134400]
>>>>>>>> dm-6: error: dax access failed (-5) [66567.139152] dm-6: error:
>>>>>>>> dax access failed (-5) [66567.314546] dm-2: error: dax access
>>>>>>>> failed (-95) [66567.319380] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.324254] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.479025] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.483713] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.488722] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.494061] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.498823] dm-2: error: dax access failed (-95)
>>>>>>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>>>>>>
>>>>>>>> commit 231609785cbfb must be reverted.
>>>>>>>>
>>>>>>>> Please advise, thanks.
>>>>>>>
>>>>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not
>>>>>>> print error message for non-persistent memory block device
>>>>>>>
>>>>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>>>>>
>>>>>> OK, yes sounds like it.  It was merged and is commit
>>>>>> c2affe920b0e066
>>>>>> ("dax: do not print error message for non-persistent memory block
>>>>>> device")
>>>>>
>>>>> Thanks for informing me this patch is merged, I am going to update
>>>>> my local one :-)
>>>>
>>>> So the thing is I'm running v5.9-rc3 (which includes this commit) but
>>>> I'm still seeing all these warnings when I run the lvm2 testsuite.
>>>> The reason _seems_ to be because the lvm2 testsuite uses brd devices
>>>> for test devices.  So there is something about the brd device that
>>>> shows commit c2affe920b0e066 isn't enough :(
>>>
>>> [Resend and CC Adrian Huang]
>>>
>>> Hi Mike,
>>>
>>> Could you please apply and test this attached patch based on v5.9-rc3 ?
>>>
>>> It seems the pointer dax_dev of __generic_fsdax_supported() parameter
>>> is not initialized (IMHO this is not a dm bug), therefore the &&
>>> should be
>>> || to check the dax support state.
>>>
>>> Also I add two pr_info() to print the variables value, let's see
>>> whether my guess makes sense.
>>
>> Also I suggest some kind of change like this in drivers/md/dm.c,
>>
>> diff --git a/drivers/md/dm.c b/drivers/md/dm.c index
>> fb0255d25e4b..566d8208df47 100644
>> --- a/drivers/md/dm.c
>> +++ b/drivers/md/dm.c
>> @@ -818,6 +818,8 @@ int dm_get_table_device(struct mapped_device *md,
>> dev_t dev, fmode_t mode,
>>                         return -ENOMEM;
>>                 }
>>
>> +               memset(td, 0, sizeof(struct table_device));
>> +
> 
> This does not help. See the following log.
> 
> -----------------
> # lvm2-testsuite --only activate-minor
> .......
> [ 0:00] #activate-minor.sh:22+ aux prepare_vg 2
> [ 0:00] ## preparing ramdisk device...ok (/dev/ram0)
> [ 0:01] 6,3160,150710756,-;brd: module loaded
> [ 0:01] ## preparing 2 devices...ok
> [ 0:01] 6,3161,150730864,-;dax_dev: 0000000000000000
> [ 0:01] 6,3162,150730866,-;bdev_dax_supported(): 0
> [ 0:01] 6,3163,150730903,-;dax_dev: 0000000000000000
> [ 0:01] 6,3164,150730905,-;bdev_dax_supported(): 0
> [ 0:01] 6,3165,150731019,-;dax_dev: 0000000000000000
> [ 0:01] 6,3166,150731020,-;bdev_dax_supported(): 0
> [ 0:01] 6,3167,150731512,-;dax_dev: 0000000000000000
> [ 0:01] 6,3168,150731514,-;bdev_dax_supported(): 0
> [ 0:01] 6,3169,150731525,-;dax_dev: 0000000000000000
> [ 0:01] 6,3170,150731525,-;bdev_dax_supported(): 0
> [ 0:01] 6,3171,150731656,-;dax_dev: 0000000000000000
> [ 0:01] 6,3172,150731657,-;bdev_dax_supported(): 0
> .......
> [ 0:01] lvchange $vg/foo -a y
> [ 0:01] #activate-minor.sh:25+ lvchange LVMTEST12302vg/foo -a y
> [ 0:01]   /tmp/LVMTEST12302.W0HGxyzxst/dev/mapper/LVMTEST12302vg-foo not set up by udev: Falling back to direct node creation.
> [ 0:01] 6,3173,150927070,-;dax_dev: 00000000f0a5865d
> [ 0:01] 6,3174,150927072,-;bdev_dax_supported(): 0
> [ 0:01] 6,3175,150927081,-;dax_dev: 00000000f0a5865d
> [ 0:01] 6,3176,150927082,-;bdev_dax_supported(): 0
> [ 0:01] 6,3177,150927241,-;dax_dev: 00000000f0a5865d
> [ 0:01] 6,3178,150927242,-;bdev_dax_supported(): 0
> ----------------


It seems I didn't cache all the locations to set dax_dev pointer to NULL
if the defice does not support dax. Thanks for point out of this :-)

Coly Li
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RE: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Adrian Huang12]

Hi Coly,

> -----Original Message-----
> From: Coly Li <colyli@suse.de>
> Sent: Thursday, September 3, 2020 1:20 PM
> To: Mike Snitzer <snitzer@redhat.com>
> Cc: Jan Kara <jack@suse.com>; Ira Weiny <ira.weiny@intel.com>; Pankaj Gupta
> <pankaj.gupta.linux@gmail.com>; Vishal Verma <vishal.l.verma@intel.com>;
> linux-nvdimm@lists.01.org; Adrian Huang12 <ahuang12@lenovo.com>
> Subject: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9
> commit 231609785cbfb
> 
> On 2020/9/3 00:51, Mike Snitzer wrote:
> > On Wed, Sep 02 2020 at 12:46pm -0400,
> > Coly Li <colyli@suse.de> wrote:
> >
> >> On 2020/9/3 00:44, Mike Snitzer wrote:
> >>> On Wed, Sep 02 2020 at 12:40pm -0400, Coly Li <colyli@suse.de>
> >>> wrote:
> >>>
> >>>> On 2020/9/3 00:04, Mike Snitzer wrote:
> >>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info()
> >>>>> in
> >>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
> >>>>>
> >>>>> The justification in the commit header is really inadequate.  If
> >>>>> there is a problem that you need to drill in on, repeat the
> >>>>> testing after enabling the dynamic debugging.
> >>>>>
> >>>>> Otherwise, now all DM devices that aren't layered on DAX capable
> >>>>> devices spew really confusing noise to users when they simply
> >>>>> activate their non-DAX DM devices:
> >>>>>
> >>>>> [66567.129798] dm-6: error: dax access failed (-5) [66567.134400]
> >>>>> dm-6: error: dax access failed (-5) [66567.139152] dm-6: error:
> >>>>> dax access failed (-5) [66567.314546] dm-2: error: dax access
> >>>>> failed (-95) [66567.319380] dm-2: error: dax access failed (-95)
> >>>>> [66567.324254] dm-2: error: dax access failed (-95) [66567.479025]
> >>>>> dm-2: error: dax access failed (-95) [66567.483713] dm-2: error:
> >>>>> dax access failed (-95) [66567.488722] dm-2: error: dax access
> >>>>> failed (-95) [66567.494061] dm-2: error: dax access failed (-95)
> >>>>> [66567.498823] dm-2: error: dax access failed (-95) [66567.503693]
> >>>>> dm-2: error: dax access failed (-95)
> >>>>>
> >>>>> commit 231609785cbfb must be reverted.
> >>>>>
> >>>>> Please advise, thanks.
> >>>>
> >>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not
> >>>> print error message for non-persistent memory block device
> >>>>
> >>>> It fixes the issue, but no response for now. Maybe we should take this fix.
> >>>
> >>> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
> >>> ("dax: do not print error message for non-persistent memory block
> >>> device")
> >>
> >> Thanks for informing me this patch is merged, I am going to update my
> >> local one :-)
> >
> > So the thing is I'm running v5.9-rc3 (which includes this commit) but
> > I'm still seeing all these warnings when I run the lvm2 testsuite.
> > The reason _seems_ to be because the lvm2 testsuite uses brd devices
> > for test devices.  So there is something about the brd device that
> > shows commit c2affe920b0e066 isn't enough :(
> 
> [Resend and CC Adrian Huang]
> 
> Hi Mike,
> 
> Could you please apply and test this attached patch based on v5.9-rc3 ?
> 
> It seems the pointer dax_dev of __generic_fsdax_supported() parameter is not
> initialized (IMHO this is not a dm bug), therefore the && should be
> || to check the dax support state.
>
> Also I add two pr_info() to print the variables value, let's see whether my guess
> makes sense.

I confirmed that Mike's symptom can be easily reproduced with brd devices after running the tool 'lvm2-testsuite'.

And, Coly's right. The dax_dev pointer is *NOT* NULL when the tool executes the command ' lvchange $vg/foo -a y'. Please see the following log (with applying Coly's patch).

So, the 'if' statement should be logical OR operator instead of logical AND operator. Thanks, Coly.

------------------------------------------------------
# lvm2-testsuite --only activate-minor
....
[ 0:00] aux prepare_vg 2
[ 0:00] #activate-minor.sh:22+ aux prepare_vg 2
[ 0:00] ## preparing ramdisk device...ok (/dev/ram0)
[ 0:01] 6,3160,167857640,-;brd: module loaded
[ 0:01] ## preparing 2 devices...ok
[ 0:01] 6,3161,167877024,-;dax_dev: 0000000000000000
[ 0:01] 6,3162,167877026,-;bdev_dax_supported(): 0
[ 0:01] 6,3163,167877041,-;dax_dev: 0000000000000000
[ 0:01] 6,3164,167877042,-;bdev_dax_supported(): 0
[ 0:01] 6,3165,167877160,-;dax_dev: 0000000000000000
[ 0:01] 6,3166,167877162,-;bdev_dax_supported(): 0
[ 0:01] 6,3167,167877407,-;dax_dev: 0000000000000000
[ 0:01] 6,3168,167877412,-;bdev_dax_supported(): 0
[ 0:01] 6,3169,167877430,-;dax_dev: 0000000000000000
[ 0:01] 6,3170,167877430,-;bdev_dax_supported(): 0
[ 0:01] 6,3171,167877572,-;dax_dev: 0000000000000000
[ 0:01] 6,3172,167877574,-;bdev_dax_supported(): 0
.......
[ 0:01] lvchange $vg/foo -a y
[ 0:01] #activate-minor.sh:25+ lvchange LVMTEST12338vg/foo -a y
[ 0:01]   /tmp/LVMTEST12338.9M4A4QfLHQ/dev/mapper/LVMTEST12338vg-foo not set up by udev: Falling back to direct node creation.
[ 0:01] 6,3173,168081520,-;dax_dev: 000000007f8e88a7
[ 0:01] 6,3174,168081524,-;bdev_dax_supported(): 0
[ 0:01] 6,3175,168081543,-;dax_dev: 000000007f8e88a7
[ 0:01] 6,3176,168081544,-;bdev_dax_supported(): 0
[ 0:01] 6,3177,168081749,-;dax_dev: 000000007f8e88a7
[ 0:01] 6,3178,168081750,-;bdev_dax_supported(): 0
-----------------------------------------------------

> Thanks.
> 
> Coly Li
> 

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Re: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 19:09, Adrian Huang12 wrote:
> Hi Coly,
> 
>> -----Original Message-----
>> From: Coly Li <colyli@suse.de>
>> Sent: Thursday, September 3, 2020 1:20 PM
>> To: Mike Snitzer <snitzer@redhat.com>
>> Cc: Jan Kara <jack@suse.com>; Ira Weiny <ira.weiny@intel.com>; Pankaj Gupta
>> <pankaj.gupta.linux@gmail.com>; Vishal Verma <vishal.l.verma@intel.com>;
>> linux-nvdimm@lists.01.org; Adrian Huang12 <ahuang12@lenovo.com>
>> Subject: [External] Re: flood of "dm-X: error: dax access failed" due to 5.9
>> commit 231609785cbfb
>>
>> On 2020/9/3 00:51, Mike Snitzer wrote:
>>> On Wed, Sep 02 2020 at 12:46pm -0400,
>>> Coly Li <colyli@suse.de> wrote:
>>>
>>>> On 2020/9/3 00:44, Mike Snitzer wrote:
>>>>> On Wed, Sep 02 2020 at 12:40pm -0400, Coly Li <colyli@suse.de>
>>>>> wrote:
>>>>>
>>>>>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>>>>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info()
>>>>>>> in
>>>>>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>>>>>
>>>>>>> The justification in the commit header is really inadequate.  If
>>>>>>> there is a problem that you need to drill in on, repeat the
>>>>>>> testing after enabling the dynamic debugging.
>>>>>>>
>>>>>>> Otherwise, now all DM devices that aren't layered on DAX capable
>>>>>>> devices spew really confusing noise to users when they simply
>>>>>>> activate their non-DAX DM devices:
>>>>>>>
>>>>>>> [66567.129798] dm-6: error: dax access failed (-5) [66567.134400]
>>>>>>> dm-6: error: dax access failed (-5) [66567.139152] dm-6: error:
>>>>>>> dax access failed (-5) [66567.314546] dm-2: error: dax access
>>>>>>> failed (-95) [66567.319380] dm-2: error: dax access failed (-95)
>>>>>>> [66567.324254] dm-2: error: dax access failed (-95) [66567.479025]
>>>>>>> dm-2: error: dax access failed (-95) [66567.483713] dm-2: error:
>>>>>>> dax access failed (-95) [66567.488722] dm-2: error: dax access
>>>>>>> failed (-95) [66567.494061] dm-2: error: dax access failed (-95)
>>>>>>> [66567.498823] dm-2: error: dax access failed (-95) [66567.503693]
>>>>>>> dm-2: error: dax access failed (-95)
>>>>>>>
>>>>>>> commit 231609785cbfb must be reverted.
>>>>>>>
>>>>>>> Please advise, thanks.
>>>>>>
>>>>>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not
>>>>>> print error message for non-persistent memory block device
>>>>>>
>>>>>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>>>>
>>>>> OK, yes sounds like it.  It was merged and is commit c2affe920b0e066
>>>>> ("dax: do not print error message for non-persistent memory block
>>>>> device")
>>>>
>>>> Thanks for informing me this patch is merged, I am going to update my
>>>> local one :-)
>>>
>>> So the thing is I'm running v5.9-rc3 (which includes this commit) but
>>> I'm still seeing all these warnings when I run the lvm2 testsuite.
>>> The reason _seems_ to be because the lvm2 testsuite uses brd devices
>>> for test devices.  So there is something about the brd device that
>>> shows commit c2affe920b0e066 isn't enough :(
>>
>> [Resend and CC Adrian Huang]
>>
>> Hi Mike,
>>
>> Could you please apply and test this attached patch based on v5.9-rc3 ?
>>
>> It seems the pointer dax_dev of __generic_fsdax_supported() parameter is not
>> initialized (IMHO this is not a dm bug), therefore the && should be
>> || to check the dax support state.
>>
>> Also I add two pr_info() to print the variables value, let's see whether my guess
>> makes sense.
> 
> I confirmed that Mike's symptom can be easily reproduced with brd devices after running the tool 'lvm2-testsuite'.
> 
> And, Coly's right. The dax_dev pointer is *NOT* NULL when the tool executes the command ' lvchange $vg/foo -a y'. Please see the following log (with applying Coly's patch).
> 
> So, the 'if' statement should be logical OR operator instead of logical AND operator. Thanks, Coly.
> 
> ------------------------------------------------------
> # lvm2-testsuite --only activate-minor
> ....
> [ 0:00] aux prepare_vg 2
> [ 0:00] #activate-minor.sh:22+ aux prepare_vg 2
> [ 0:00] ## preparing ramdisk device...ok (/dev/ram0)
> [ 0:01] 6,3160,167857640,-;brd: module loaded
> [ 0:01] ## preparing 2 devices...ok
> [ 0:01] 6,3161,167877024,-;dax_dev: 0000000000000000
> [ 0:01] 6,3162,167877026,-;bdev_dax_supported(): 0
> [ 0:01] 6,3163,167877041,-;dax_dev: 0000000000000000
> [ 0:01] 6,3164,167877042,-;bdev_dax_supported(): 0
> [ 0:01] 6,3165,167877160,-;dax_dev: 0000000000000000
> [ 0:01] 6,3166,167877162,-;bdev_dax_supported(): 0
> [ 0:01] 6,3167,167877407,-;dax_dev: 0000000000000000
> [ 0:01] 6,3168,167877412,-;bdev_dax_supported(): 0
> [ 0:01] 6,3169,167877430,-;dax_dev: 0000000000000000
> [ 0:01] 6,3170,167877430,-;bdev_dax_supported(): 0
> [ 0:01] 6,3171,167877572,-;dax_dev: 0000000000000000
> [ 0:01] 6,3172,167877574,-;bdev_dax_supported(): 0
> .......
> [ 0:01] lvchange $vg/foo -a y
> [ 0:01] #activate-minor.sh:25+ lvchange LVMTEST12338vg/foo -a y
> [ 0:01]   /tmp/LVMTEST12338.9M4A4QfLHQ/dev/mapper/LVMTEST12338vg-foo not set up by udev: Falling back to direct node creation.
> [ 0:01] 6,3173,168081520,-;dax_dev: 000000007f8e88a7
> [ 0:01] 6,3174,168081524,-;bdev_dax_supported(): 0
> [ 0:01] 6,3175,168081543,-;dax_dev: 000000007f8e88a7
> [ 0:01] 6,3176,168081544,-;bdev_dax_supported(): 0
> [ 0:01] 6,3177,168081749,-;dax_dev: 000000007f8e88a7
> [ 0:01] 6,3178,168081750,-;bdev_dax_supported(): 0
> -----------------------------------------------------

Hi Adrian,

Thanks for double check. I will post the fixes for you and Mike to review.

Coly Li
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Verma, Vishal L]

On Thu, 2020-09-03 at 00:40 +0800, Coly Li wrote:
> On 2020/9/3 00:04, Mike Snitzer wrote:
> > 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
> > __generic_fsdax_supported()") switched from pr_debug() to pr_info().
> > 
> > The justification in the commit header is really inadequate.  If there
> > is a problem that you need to drill in on, repeat the testing after
> > enabling the dynamic debugging.
> > 
> > Otherwise, now all DM devices that aren't layered on DAX capable devices
> > spew really confusing noise to users when they simply activate their
> > non-DAX DM devices:
> > 
> > [66567.129798] dm-6: error: dax access failed (-5)
> > [66567.134400] dm-6: error: dax access failed (-5)
> > [66567.139152] dm-6: error: dax access failed (-5)
> > [66567.314546] dm-2: error: dax access failed (-95)
> > [66567.319380] dm-2: error: dax access failed (-95)
> > [66567.324254] dm-2: error: dax access failed (-95)
> > [66567.479025] dm-2: error: dax access failed (-95)
> > [66567.483713] dm-2: error: dax access failed (-95)
> > [66567.488722] dm-2: error: dax access failed (-95)
> > [66567.494061] dm-2: error: dax access failed (-95)
> > [66567.498823] dm-2: error: dax access failed (-95)
> > [66567.503693] dm-2: error: dax access failed (-95)
> > 
> > commit 231609785cbfb must be reverted.
> > 
> > Please advise, thanks.
> 
> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
> error message for non-persistent memory block device
> 
> It fixes the issue, but no response for now. Maybe we should take this fix.
> 

Mike, Coly,

I applied Adrians patch, and submitted it - it is already in v5.9-rc3 -
c2affe920b0e dax: do not print error message for non-persistent memory block device
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Re: flood of "dm-X: error: dax access failed" due to 5.9 commit 231609785cbfb

[Coly Li]

On 2020/9/3 07:05, Verma, Vishal L wrote:
> On Thu, 2020-09-03 at 00:40 +0800, Coly Li wrote:
>> On 2020/9/3 00:04, Mike Snitzer wrote:
>>> 5.9 commit 231609785cbfb ("dax: print error message by pr_info() in
>>> __generic_fsdax_supported()") switched from pr_debug() to pr_info().
>>>
>>> The justification in the commit header is really inadequate.  If there
>>> is a problem that you need to drill in on, repeat the testing after
>>> enabling the dynamic debugging.
>>>
>>> Otherwise, now all DM devices that aren't layered on DAX capable devices
>>> spew really confusing noise to users when they simply activate their
>>> non-DAX DM devices:
>>>
>>> [66567.129798] dm-6: error: dax access failed (-5)
>>> [66567.134400] dm-6: error: dax access failed (-5)
>>> [66567.139152] dm-6: error: dax access failed (-5)
>>> [66567.314546] dm-2: error: dax access failed (-95)
>>> [66567.319380] dm-2: error: dax access failed (-95)
>>> [66567.324254] dm-2: error: dax access failed (-95)
>>> [66567.479025] dm-2: error: dax access failed (-95)
>>> [66567.483713] dm-2: error: dax access failed (-95)
>>> [66567.488722] dm-2: error: dax access failed (-95)
>>> [66567.494061] dm-2: error: dax access failed (-95)
>>> [66567.498823] dm-2: error: dax access failed (-95)
>>> [66567.503693] dm-2: error: dax access failed (-95)
>>>
>>> commit 231609785cbfb must be reverted.
>>>
>>> Please advise, thanks.
>>
>> Adrian Huang from Lenovo posted a patch, which titled: dax: do not print
>> error message for non-persistent memory block device
>>
>> It fixes the issue, but no response for now. Maybe we should take this fix.
>>
> 
> Mike, Coly,
> 
> I applied Adrians patch, and submitted it - it is already in v5.9-rc3 -
> c2affe920b0e dax: do not print error message for non-persistent memory block device
> 

Hi Verma,

Thank you for taking it into mainline :-)

Coly Li
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