Re: Fragmented physical memory on powerpc/32

From: Christophe Leroy
Date: Tue Sep 13 2022 - 08:36:40 EST

Le 13/09/2022 à 08:11, Christophe Leroy a écrit :

Le 12/09/2022 à 23:16, Pali Rohár a écrit :

My guess would be that something went wrong in the linear map setup, but it
won't hurt running with "memblock=debug" added to the kernel command line
to see if there is anything suspicious there.

Here is boot log on serial console with memblock=debug command line:


Do you need something more for debug?

Can you send me the 'vmlinux' used to generate the above Oops so that I can see exactly where we are in function mem_init().

And could you also try without CONFIG_HIGHMEM just in case.

I looked at the vmlinux you sent me, the problem is in the loop for highmem in mem_init(). It crashes in the call to free_highmem_page()

unsigned long pfn, highmem_mapnr;

highmem_mapnr = lowmem_end_addr >> PAGE_SHIFT;
for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
phys_addr_t paddr = (phys_addr_t)pfn << PAGE_SHIFT;
struct page *page = pfn_to_page(pfn);
if (!memblock_is_reserved(paddr))
#endif /* CONFIG_HIGHMEM */

As far as I can see in the memblock debug lines, the holes don't seem to be marked as reserved by memblock. So it is above valid ? Other architectures seem to do differently.

Can you try by replacing !memblock_is_reserved(paddr) by memblock_is_memory(paddr) ?