Re: Crash in msm serial on kernel 6.12

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Sep 01, 2025 at 04:40:42PM +0200, Koen Vandeputte wrote:
> Hi all,
> 
> I just updated my ipq4019 boards on OpenWRT from kernel 6.6 to 6.12.
> 
> When using the serial port (/dev/ttyMSM1) I notice that it keeps
> crashing while using that port.
> 
> Going through the commit history, I noticed that not much changed at
> all compared to kernel 6.6:
> 
> f6ae572683d4 serial: msm: Configure correct working mode before
> starting earlycon
> f70f95b485d7 serial: msm: check dma_map_sg() return value properly
> 1788cf6a91d9 tty: serial: switch from circ_buf to kfifo
> f8fef2fa419f tty: msm_serial: use dmaengine_prep_slave_sg()
> 4e5788c0993c serial: msm: Use uart_prepare_sysrq_char().
> 173ebdedcd84 serial: msm: Use OPP table for DVFS support
> a63e5a49d596 serial: msm: Convert to platform remove callback returning void
> 6cbd979080c7 serial: msm: Use port lock wrappers
> 
> As the crash indicates, it has got something to do with DMA transfers,
> which was altered in these 3 commits:
> 
> f70f95b485d7 serial: msm: check dma_map_sg() return value properly
> 1788cf6a91d9 tty: serial: switch from circ_buf to kfifo
> f8fef2fa419f tty: msm_serial: use dmaengine_prep_slave_sg()
> 
> 
> file:  ./drivers/tty/serial/msm_serial.c
> crashing function: msm_start_rx_dma()

Can you do 'git bisect' to track down the offending commit?  And what
about 6.16?

thanks,

greg k-h