mm: khugepaged: remove redundant check for VM_NO_KHUGEPAGED

The hugepage_vma_check() called by khugepaged_enter_vma_merge() does check
VM_NO_KHUGEPAGED.  Remove the check from caller and move the check in
hugepage_vma_check() up.

More checks may be run for VM_NO_KHUGEPAGED vmas, but MADV_HUGEPAGE is
definitely not a hot path, so cleaner code does outweigh.

Link: https://lkml.kernel.org/r/20220510203222.24246-3-shy828301@gmail.comSigned-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Vlastmil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged.c

@@ -365,8 +365,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
 		 * register it here without waiting a page fault that
 		 * may not happen any time soon.
 		 */
-		if (!(*vm_flags & VM_NO_KHUGEPAGED) &&
-				khugepaged_enter_vma_merge(vma, *vm_flags))
+		if (khugepaged_enter_vma_merge(vma, *vm_flags))
 			return -ENOMEM;
 		break;
 	case MADV_NOHUGEPAGE:
@@ -445,6 +444,9 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
 	if (!transhuge_vma_enabled(vma, vm_flags))
 		return false;
 
+	if (vm_flags & VM_NO_KHUGEPAGED)
+		return false;
+
 	if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
 				vma->vm_pgoff, HPAGE_PMD_NR))
 		return false;
@@ -470,7 +472,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
 		return false;
 	if (vma_is_temporary_stack(vma))
 		return false;
-	return !(vm_flags & VM_NO_KHUGEPAGED);
+
+	return true;
 }
 
 int __khugepaged_enter(struct mm_struct *mm)