Re: Your System ate a SPARC! Gah! in map_pages()

[Helge Deller <deller@gmx.de>]

On 12/6/21 00:05, John David Anglin wrote:
> On 2021-12-05 4:00 p.m., John David Anglin wrote:
>>> Does it boot if you remove the __init in front of map_pages?
>> I'll try.  I thought of trying it but wasn't sure if map_pages() had to be an init routine or not.
> This appears to fix boot.  System booted okay about six times.

Do you have huge pages enabled?
If so you could try this patch (instead of markung map_pages __init):

diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index 1ae31db9988f..a9a510338ced 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -405,7 +405,7 @@ static void __init map_pages(unsigned long start_vaddr,
                                } else if (!kernel_set_to_readonly) {
                                        /* still initializing, allow writing to RO memory */
                                        prot = PAGE_KERNEL_RWX;
-                                       huge = true;
+                                       huge = false;
                                } else if (address >= ro_start) {
                                        /* Code (ro) and Data areas */
                                        prot = (address < ro_end) ?

Maybe the whole kernel is initially mapped via one/multiple huge pages(s), and
then we suddenly turn huge pages partly off. Therefore maybe not all TLB entries for the code of
map_pages() is already loaded?

On the other side the problem is somewhat similar to what I see with patching
the kernel code in the fixmap code on PA1.x CPUs... it showed strange asm statements too..

Helge