[SRU J][PATCH V3 0/1] Duplicate Device_dax ids Created and hence Probing is Failing

[Michael Reed]

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