crash in ath11k_mac_op_unassign_vif_chanctx / kernel 5.12.0-0.rc7

Tue Apr 20 11:42:47 BST 2021

Hey. I originally reported for Fedora 34 at 
https://bugzilla.redhat.com/show_bug.cgi?id=1950410 but now feel like 
this list is more appropriate.

Hardware: Dell XPS 15 9500 with newest BIOS (1.7.1 03/29/2021) and 
QCA6390 Wireless Network Adapter [AX500-DBS (2x2)]

Kernel: tested with both: 5.12.0-0.rc7 and 5.11.12-300 from Fedora 34. 
Focusing on the 5.12 one here, but the crash in 
ath11k_mac_op_unassign_vif_chanctx seems to be the same in both.

   $ uname -a
   Linux fedora 5.12.0-0.rc7.189.fc35.x86_64 #1 SMP Mon Apr 12 18:53:43 
UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Kernel log excerpt right after boot:

   [   27.093803] RIP: 0010:ath11k_mac_op_unassign_vif_chanctx+0x17e/0x1d0 [ath11k]

   [   27.093876] Call Trace:
   [   27.093885]  ieee80211_assign_vif_chanctx+0x8b/0x420 [mac80211]
   [   27.093989]  ? ath11k_mac_op_bss_info_changed+0x3c/0xc60 [ath11k]
   [   27.094017]  __ieee80211_vif_release_channel+0x4f/0x130 [mac80211]
   [   27.094103]  ieee80211_vif_release_channel+0x3a/0x50 [mac80211]
   [   27.094185]  ieee80211_mgd_auth.cold+0x10d/0x167 [mac80211]
   [   27.094289]  cfg80211_mlme_auth+0x113/0x1d0 [cfg80211]
   [   27.094402]  nl80211_authenticate+0x296/0x2f0 [cfg80211]

Is this expected? https://bugzilla.kernel.org/show_bug.cgi?id=211569 
sounded promising to me, that this hardware is going to work in 5.12 -- 
however the thread also left ambiguitiy for, especially the

 > But unfortunately it was crashing and I couldn't take it to v5.12
 > (the deadline was yesterday). So it will have to wait for v5.13,
 > if we can fix the crashes. And I'm optimistic we can, but
 > I cannot promise anything.

* Is it likely that I can address this by changing configuration?
* If this crash is unexpected an not understood: can I help by providing 
further information?
* What can I do to make this Wifi hardware work? Build a custom kernel?

Thank you for help, and also for understanding that my competence in 
this area is limited. Happy to learn.

Jan-Philip