Re: [PATCH] eeprom: at25: convert to spi-mem API

[Christophe Leroy]

Hi Alexander,

Le 04/11/2025 à 14:13, Sverdlin, Alexander a écrit :
> Hi Christophe,
>
> On Mon, 2025-11-03 at 23:36 +0100, Christophe Leroy wrote:
> > > > > > > Replace the RAW SPI accesses with spi-mem API. The latter will fall back to
> > > > > > > RAW SPI accesses if spi-mem callbacks are not implemented by a controller
> > > > > > > driver.
> > > > > >
> > > > > > With this patch (kernel v6.17.1) our powerpc boards are totally
> > > > > > unstable, we get multiple random Oops due to bad memory accesses.
> > > > > >
> > > > > > With this commit reverted the board is stable again.
> > > > > >
> > > > > > The SPI driver is:
> > > > > >
> > > > > > CONFIG_SPI=y
> > > > > > CONFIG_SPI_MASTER=y
> > > > > > CONFIG_SPI_MEM=y
> > > > > > CONFIG_SPI_FSL_LIB=y
> > > > > > CONFIG_SPI_FSL_CPM=y
> > > > > > CONFIG_SPI_FSL_SPI=y
> > > > > >
> > > > > > How can we further investigate the issue ?
> > > > >
> > > > > could you share these "random Oops"?
> > > >
> > > > Sure. At the first place they look unrelated. Something is likely
> > >
> > > indeed, no obvious connection... Do you have a chance to run KASAN?
> >
> > I ran KASAN, it found an overrun in the loop in
> > fsl_spi_cpm_bufs_complete() when t->len is odd, but once fixed the
> > random problem is still there.
>
> thanks for the quick reply!
> That sounds promising already!
>
> Do you have a chance to run with CONFIG_DEBUG_STACKOVERFLOW=y ?

Unfortunately I won't be able to do any additionnal test until Monday 
next week as I'm travelling at the moment.

However, our kernel is built with CONFIG_VMAP_STACK, so a stack overflow 
would have been caught by the early stack overflow detection, see commit 
3978eb78517c ("powerpc/32: Add early stack overflow detection with VMAP 
stack.") for details.

Christophe