Hi Coly,
> -----Original Message-----
> From: Coly Li <col...@suse.de>
> Sent: Thursday, September 3, 2020 1:20 PM
> To: Mike Snitzer <snit...@redhat.com>
> Cc: Jan Kara <j...@suse.com>; Ira Weiny <ira.we...@intel.com>; Pankaj Gupta
> <pankaj.gupta.li...@gmail.com>; Vishal Verma <vishal.l.ve...@intel.com>;
> linux-nvdimm@lists.01.org; Adrian Huang12 <ahuan...@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 <col...@suse.de> wrote:
> >
> >> On 2020/9/3 00:44, Mike Snitzer wrote:
> >>> On Wed, Sep 02 2020 at 12:40pm -0400, Coly Li <col...@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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