mt7921: Oops in mt76_dma_rx_fill

Hi,

on the latest stable 5.16.8 (df659ebe) the Mediatek WLAN driver crashes on my machine in a DMA function.

Please excuse me for the crappy photos. The first one has been captured out of a video. Therefore it's partially interleaved with the predecessor frame.

https://bues.ch/misc/mt7921/mt7921_oops1.jpg
https://bues.ch/misc/mt7921/mt7921_oops2.jpg

Most of the time the crash happens right during system boot.

The stable kernel 5.15.y does not crash. (However, I frequently get connection interruptions. But I'm not sure whether that's related to the driver.)

03:00.0 Network controller: MEDIATEK Corp. MT7921 802.11ax PCI Express Wireless Network Adapter

03:00.0 0280: 14c3:7961
Subsystem: 17aa:e0bc
Physical Slot: 0
Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0, Cache Line Size: 32 bytes
Interrupt: pin A routed to IRQ 94
IOMMU group: 11
Region 0: Memory at 670200000 (64-bit, prefetchable) [size=1M]
Region 2: Memory at 670300000 (64-bit, prefetchable) [size=16K]
Region 4: Memory at 670304000 (64-bit, prefetchable) [size=4K]
Capabilities: <access denied>
Kernel driver in use: mt7921e
Kernel modules: mt7921e

Michael Büsch
https://bues.ch/

Does anybody have an idea why this driver crashes?

I tried to bisect it. But that turns out to be very hard as the intermediate versions are all very unstable, too. For various reasons. Therefore, I aborted my bisect attempt.

But if you have an idea what patch I could try, I'd be very happy to do so.

Michael Büsch
https://bues.ch/


On Wed, 9 Feb 2022 17:05:50 +0100