On Wed, 26 Jun 2019, Christophe Leroy wrote:

Hi Finn,

On 06/26/2019 02:06 AM, Finn Thain wrote:

quoted

Hi Christophe,

I received a report of a regression between v5.0 and v5.1 which causes 
the current release to crash during boot with a machine check 
exception. Please see console log below.

Stan (whom I've Cc'd) tells me that this happens on every attempt to 
boot. I asked him to try 'git bisect'. The results are given below. 
Can you see anything in commit 93c4a162b014 that might explain this?

Might be a false positive. That commit has a problem, but that problem 
is fixed by 4622a2d43101 ("powerpc/6xx: fix setup and use of 
SPRN_SPRG_PGDIR for hash32")

I would bet your problem is related to commit f7354ccac844 ("powerpc/32: 
Remove CURRENT_THREAD_INFO and rename TI_CPU"). That problem is fixed by 
commit 397d2300b08c ("powerpc/32s: fix flush_hash_pages() on SMP") 
upstream, and in linux 5.1.4 by commit fda49aec2515 on 
stable/linux-5.1.y

I see. I've just discovered that this issue has already been covered on 
this list. I should have done a bit more research.

Can you test ?

Stan did some more tests and confirmed that the problem has been fixed in 
397d2300b08c and stable/linux-5.1.y.

Thanks.

-- 

Thanks
Christophe