UML kernel panic on initialization

[Johannes Berg]

On Tue, 2021-07-13 at 21:26 +0200, Johannes Berg wrote:
> On Tue, 2021-07-13 at 21:22 +0200, Johannes Berg wrote:
> > On Sat, 2021-07-10 at 15:00 -0600, subashab at codeaurora.org wrote:
> > > 
> > > I have reverted the following patches (to allow for a clean revert)
> > > and I don't see the panic anymore -
> > > 
> > > bfc58e2b98e99737409cd9f4d86a79677c5b887c
> > > dc01a3b9db43abf95b801c9694980777a329e303
> > > 9f0b4807a44ff81cf59421c8a86641efec586610
> > > 84b2789d61156db0224724806b20110c0d34b07c
> > 
> > Out of those 4, the last ("separate child and...") seems actually less
> > intrusive than the previous one. If you revert only the first three of
> > this list, does it still happen?
> > 
> > Does it still happen if you unset CONFIG_CC_OPTIMIZE_FOR_SIZE and do
> > CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE instead?
> 
> Oh, and it looks like 84b2789d6115 actually got some bits that shouldn't
> have been there!
> 
> Assuming it does *not* work with just the first three patches reverted,
> does it work again if you revert the first three patches, and only this
> bit of the fourth?

[snip]

And as yet another experiment in this area, does it work again if you
apply this patch?

https://patchwork.ozlabs.org/project/linux-um/patch/20210303155523.124277-11-benjamin@sipsolutions.net/

Not sure it applies as-is, but you can see the schema there.

johannes