Boot failed after patch "mtd: rawnand: Support for sequential cache reads"

[Miquel Raynal]

Hi Alexander,

eagle.alexander923 at gmail.com wrote on Thu, 25 May 2023 10:48:39 +0300:

> Hello.
> 
> Kernel boot fails after patch "mtd: rawnand: Support for sequential
> cache reads" (thanks to git bisect).
> Please advise what can be done here and where to look for a bug.

Thanks for the report, and sorry for the trouble. Right now I don't
know what's wrong with the driver but as a first step, you could just
try to reset chip->controller->supported_op.cont_read after
rawnand_check_cont_read_support(). It should just avoid using the
optimization and solve the boot. That's of course a very early fix, we
now need to understand further what's going on.

My first guess would be that the sequential read patterns are not
supported by the controller or badly implemented by its driver. But
that is strange given the simplicity of this controller. This
controller is meant to be versatile, I doubt it does not support these
operations. Plus, I would expect page accesses to be directly
implemented by the driver and not be affected by this logic. Could you
try to trace the actual calls which are made through the mtd layer
which lead to these errors? Is ->exec_op() involved in the process?
Where? How?

Also, what kernel are you using exactly? I'm surprised there is no
mtd-related error. If you reboot with an older kernel, you get your
data, right?

Otherwise maybe the Micron chip is in fault. Which would mean that
there are unsupported commands. I believed they were all standard,
maybe some of them are optional? Could you check in the chip datasheet
if there is any command used there that is unsupported?

> 
> Thanks.
> 
> ...
> omap-gpmc 50000000.gpmc: GPMC revision 6.0
> ...
> nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xda
> nand: Micron MT29F2G08ABAEAWP
> nand: 256 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
> nand: using OMAP_ECC_BCH8_CODE_HW ECC scheme
> ...
> VFS: Mounted root (squashfs filesystem) readonly on device 254:0.
> devtmpfs: mounted
> Freeing unused kernel image (initmem) memory: 1024K
> Run /sbin/init as init process
> SQUASHFS error: lzo decompression failed, data probably corrupt
> SQUASHFS error: Failed to read block 0xd291c2: -5
> SQUASHFS error: lzo decompression failed, data probably corrupt
> SQUASHFS error: Failed to read block 0xd291c2: -5
> SQUASHFS error: Unable to read data cache entry [d291c2]
> SQUASHFS error: Unable to read page, block d291c2, size 14307
> SQUASHFS error: Unable to read data cache entry [d291c2]
> SQUASHFS error: Unable to read page, block d291c2, size 14307
> Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x00000007 CPU: 0 PID: 1 Comm: init Not tainted 6.3.0+ #105
> Hardware name: Generic AM33XX (Flattened Device Tree)
>  unwind_backtrace from show_stack+0xb/0xc
>  show_stack from dump_stack_lvl+0x2b/0x34
>  dump_stack_lvl from panic+0xbd/0x230
>  panic from make_task_dead+0x1/0x120
>  make_task_dead from 0xc102ca80
> ---[ end Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x00000007 ]---


Thanks,
Miquèl