Re: [PATCH v4 1/3] x86/vmemmap: Drop handling of 4K unaligned vmemmap range

[Dave Hansen]

On 3/1/21 12:32 AM, Oscar Salvador wrote:
> remove_pte_table() is prepared to handle the case where either the
> start or the end of the range is not PAGE aligned.
> This cannot actually happen:
> 
> __populate_section_memmap enforces the range to be PMD aligned,
> so as long as the size of the struct page remains multiple of 8,
> the vmemmap range will be aligned to PAGE_SIZE.
> 
> Drop the dead code and place a VM_BUG_ON in vmemmap_{populate,free}
> to catch nasty cases.

I was wondering why the VM_BUG_ON()s went in vmemmap_free() instead of
closer to the code that you modified in remove_pte_table().  I assume
this was because vmemmap_free() is the only (indirect) caller of
remove_pte_table().

Otherwise, this looks fine to me:

Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>