mm/huge_memory.c: remove dedicated macro HPAGE_CACHE_INDEX_MASK

Patch series "Cleanup and fixup for huge_memory:, v3.

This series contains cleanups to remove dedicated macro and remove
unnecessary tlb_remove_page_size() for huge zero pmd.  Also this adds
missing read-only THP checking for transparent_hugepage_enabled() and
avoids discarding hugepage if other processes are mapping it.  More
details can be found in the respective changelogs.

Thi patch (of 5):

Rewrite the pgoff checking logic to remove macro HPAGE_CACHE_INDEX_MASK
which is only used here to simplify the code.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

include/linux/huge_mm.h

@@ -152,15 +152,13 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 
 bool transparent_hugepage_enabled(struct vm_area_struct *vma);
 
-#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
-
 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 		unsigned long haddr)
 {
 	/* Don't have to check pgoff for anonymous vma */
 	if (!vma_is_anonymous(vma)) {
-		if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
-			(vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
+		if (!IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
+				HPAGE_PMD_NR))
 			return false;
 	}