On Tue, Feb 02, 2021 at 02:29:11PM +0100, David Hildenbrand wrote:

quoted

@@ -1088,10 +1150,10 @@ remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end,
  				pages++;
  			} else {
  				/* If here, we are freeing vmemmap pages. */
-				memset((void *)addr, PAGE_INUSE, next - addr);
+				memset((void *)addr, PAGE_UNUSED, next - addr);
  				page_addr = page_address(pud_page(*pud));
-				if (!memchr_inv(page_addr, PAGE_INUSE,
+				if (!memchr_inv(page_addr, PAGE_UNUSED,
  						PUD_SIZE)) {
  					free_pagetable(pud_page(*pud),
  						       get_order(PUD_SIZE));

I'm sorry to bother you again, but isn't that dead code as well?

Heh, I spotted that earlier, but I did not think much of it honestly.

All this was introduced by:

 commit ae9aae9eda2db71bf4b592f15618b0160eb07731
 Author: Wen Congyang [off-list ref]
 Date:   Fri Feb 22 16:33:04 2013 -0800

     memory-hotplug: common APIs to support page tables hot-remove

How do we ever end up using 1GB pages for the vmemmap? At least not via
vmemmap_populate() - so I guess never? There are not many occurrences of
"PUD_SIZE" in the file after all ...

AFAICT, we don't. The largest we populate for vmemmap is 2MB.
I see init_memory_mapping can use 1G, but that should not affect us.

I guess that the vmemmap handling for 1GB can go as well.
I will update the patchset.

-- 
Oscar Salvador
SUSE L3