Re: 2.6.20 instability

[Paul M. <le...@li...>]

On Mon, Jan 29, 2007 at 10:27:19AM +0100, Manuel Lauss wrote:
> I wanted to ask if I'm the only one experiencing this:
> With 2.6.20-rc, most apps I try to launch are killed
> due to random segfaults. I tried to build udev
> on the target itself; make V=1 would fail with
> gcc simply segfaulting, sometimes /bin/sh can no longer
> be found, sometimes parts of gcc's cmdline arguments
> are missing 2-3 chars at the beginning and gcc 
> aborts with for example 
> "udev_sysdeps.c:73:1: error: ointer-arith: No such file ..."
> 
> 2.6.19 compiles xfce-4 fine so I assume this is some
> subtle sh-kernel specific fault.
> 
> I appreciate any hints!
> 
We switched the lazy dcache writeback model to PG_dcache_dirty, which
results in measurably less flushing. Unfortunately it seems like there
are still some explicit flushes required that aren't being handled.

My boards do not frequently exhibit this behaviour however, so it's slow
debugging. If you want a quick fix, you can either revert to PG_mapped
behaviour, or insert a dummy flush for the faulting page's dcache lines
in update_mmu_cache().