Re: [PATCH v1 1/3] mm: split vm_normal_pages for LRU and non-LRU handling

On Thu, Mar 10, 2022 at 11:26:31AM -0600, Alex Sierra wrote:

@@ -606,7 +606,7 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,

• PFNMAP mappings in order to support COWable mappings.

*/ -struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, +struct page *vm_normal_any_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte) { unsigned long pfn = pte_pfn(pte); @@ -620,8 +620,6 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, return NULL; if (is_zero_pfn(pfn)) return NULL;

• if (pte_devmap(pte))
  

• 	return NULL;
  
  

  print_bad_pte(vma, addr, pte, NULL); return NULL;

... what?

Haven't you just made it so that a devmap page always prints a bad PTE message, and then returns NULL anyway?

Surely this should be:

if (pte_devmap(pte)) - return NULL; + return pfn_to_page(pfn);

or maybe

+ goto check_pfn;

But I don't know about that highest_memmap_pfn check.

@@ -661,6 +659,22 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, return pfn_to_page(pfn); }

+/*

• • vm_normal_lru_page -- This function gets the "struct page" associated
• • with a pte only for page cache and anon page. These pages are LRU handled.
• */

+struct page *vm_normal_lru_page(struct vm_area_struct *vma, unsigned long addr,

• 	    pte_t pte)
  

It seems a shame to add a new function without proper kernel-doc.