Re: [GIT PULL] ARM: SoC fixes

[Tony Lindgren]

* Corentin Labbe <clabbe.montjoie@xxxxxxxxx> [181112 06:13]:
> On Sat, Nov 10, 2018 at 10:09:19AM -0800, Olof Johansson wrote:
> > On Thu, Nov 8, 2018 at 7:49 AM Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> > >
> > > * Olof Johansson <olof@xxxxxxxxx> [181107 09:28]:
> > > > On Wed, Nov 7, 2018 at 9:17 AM Linus Torvalds
> > > > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > > >
> > > > > On Wed, Nov 7, 2018 at 9:10 AM Olof Johansson <olof@xxxxxxxxx> wrote:
> > > > > >
> > > > > > ARM: SoC fixes
> > > > >
> > > > > Pulled.
> > > > >
> > > > > > I was a bit too trigger happy to enable PREEMPT on multi_v7_defconfig,
> > > > > > and it ended up regressing at least BeagleBone XM boards.
> > > > >
> > > > > Odd. Did it hit some "may_sleep()" test in a driver that is hidden by
> > > > > preempt being off? Otherwise I don't see how/why preempt should fail
> > > > > in a board-specific manner..
> > > >
> > > > The board hangs early during boot and the usual way of collecting
> > > > early console doesn't seem to work when attempted (I haven't tried
> > > > personally).
> > > >
> > > > It's one of the major non-SMP platforms covered by tests. I'd be
> > > > surprised if it turns out to be truly _board_ specific (and rather
> > > > specific to OMAP3), but we don't have enough data yet. Chances are it
> > > > either shuffles some timing around or indeed hits a may_sleep() test
> > > > somewhere.
> > > >
> > > > (I just realized I might have missed to attribute Guillaume in the
> > > > revert patch. Sorry about that).
> > >
> > > Looks like we're missing the stdout-path for earlycon, maybe try
> > > with the following patch? I can't find my Beagleboard-xm right now,
> > > time to clean-up a bit I guess.
> > >
> > > At least omap3-evm, logicpd-torpedo and n900 all boot with PREEMPT.
> > 
> > To follow up on this, it turned out to be an issue where the kernel
> > outgrew the location it was loaded to, and overwrite the device tree
> > on decompression. So, not a code issue.
> > 
> > It's a known fragile aspect on some of the u-boot setups, and
> > something I've been hit by myself on my farm a few times.
> > 
> > Still, for now we'll keep PREEMPT off until next merge window.
> > 
> 
> Hello
> 
> Note that CONFIG_PREEMPT cause some errors also on sun8i-a83t-bananapi-m3
> Already reported https://lkml.org/lkml/2017/12/29/139

Also thread "[PATCH v1 1/5] drivercore: Revert "deferral race condition fix"
is reverting commit 58b116bce136 ("drivercore: deferral race condition fix")
which has CONFIG_PREEMPT mentioned in the log. So more testing is
probably needed in Linux next before enabling CONFIG_PREEMPT again.

Regards,

Tony