[SRU][PATCH V2 0/1] Duplicate Device_dax ids Created and hence Probing is Failing

[Andrea Righi]

What is(are) the target kernel(s)/release(s) for this patch?

Thanks,
-Andrea

On Tue, Dec 12, 2023 at 04:41:31PM -0600, Michael Reed wrote:
> From: Michael Reed <Michael.Reed at canonical.com>
> 
> 
> [Impact]
> Description of problem:
> 
> Observed device_dax related probe errors in dmesg when HBM CPU is set to flat mode. Duplicate device_dax ids were created and hence probing is failing.
> 
> How reproducible:
> Frequently
> 
> Version-Release
> Release: 22.04.2, 22.10
> 
> [Test Case]
> 
> Steps to Reproduce:
> 1. Set HBM cpu to flat mode in memory settings in BIOS.
> 2. Boot to the OS.
> 3. Perform OS warm boot cycle test.
> 4. Observe the dax2.0/dax3.0/dax4.0/dax5.0 probe error.
> 
> Actual results:
> Observed device_dax related errors in dmesg, device Dax is creating dummy/duplicate devices and probe failing.
> 
> Expected results:
> Dummy/duplicate devices should not create.
> 
> [Fix]
> Upstream Fix
> https://lore.kernel.org/linux-mm/166890823379.4183293.15333502171004313377.stgit@dwillia2-xfh.jf.intel.com/T/
> 
> [Where problems could occur]
> 
> [Other Info]
>  This was initially submitted on Sept. 22, 2023
>  
> https://code.launchpad.net/~mreed8855/ubuntu/+source/linux/+git/jammy/+ref/lp_2028158_device_dax_2
> 
> Additional info:
> SUT is having 2*32C HBM cpus. Eligible system-ram mode change devices should be only 2[dax0.0, dax1.0], but under "daxctl list -u" is showing 1st time 4 devices [dax0.0, 1.0, 2.0, 3.0], 2 is "state":"disabled" and 2 more devices is "mode":"devdax" which are actuall devadax to system-ram convertible devices. After reconfigure-device dax0.0, dax1.0 when you list the devices couple of more dummy/dumplicate devices are creating with "state":"disabled"[Ex: dax4.0, 5.0 etc..].
> 
> 
> Dan Williams (1):
>   device-dax: Fix duplicate 'hmem' device registration
> 
>  drivers/dax/hmem/device.c | 26 ++++++++++++++++----------
>  1 file changed, 16 insertions(+), 10 deletions(-)
> 
> -- 
> 2.34.1
> 
> 
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