On 07/01/2018 11:16 PM, Michael Ellerman wrote:

Linus Torvalds [off-list ref] writes:

quoted

On Fri, Jun 29, 2018 at 1:42 PM Larry Finger [off-list ref] wrote:

quoted

I have more information regarding this BUG. Line 700 of page-flags.h is the
macro PAGE_TYPE_OPS(Table, table). For further debugging, I manually expanded
the macro, and found that the bug line is VM_BUG_ON_PAGE(!PageTable(page), page)
in routine __ClearPageTable(), which is called from pgtable_page_dtor() in
include/linux/mm.h. I also added a printk call to PageTable() that logs
page->page_type. The routine was called twice. The first had page_type of
0xfffffbff, which would have been expected for a . The second call had
0xffffffff, which led to the BUG.

So it looks to me like the tear-down of the page tables first found a
page that is indeed a page table, and cleared the page table bit
(well, it set it - the bits are reversed).

...

quoted

That said, can some ppc person who knows the 32-bit ppc code and maybe
knows what that "interrupt: 700" means talk about that oddity in the
trace, please?

I think everyone else answered your questions here, and it should be
fixed now in your tree.

Larry let me know if you're still seeing a crash with 4.18-rc3.

The problem is fixed in 4.18-rc3. Thanks to all that helped.

Larry