mm/vma: move VM_NO_KHUGEPAGED into generic header

Patch series "mm/vma: some more minor changes", v2.

The motivation here is to consolidate VMA flags and helpers in generic
memory header and reduce code duplication when ever applicable.  If there
are other possible similar instances which might be missing here, please
do let me me know.  I will be happy to incorporate them.

This patch (of 3):

Move VM_NO_KHUGEPAGED into generic header (include/linux/mm.h).  This just
makes sure that no VMA flag is scattered in individual function files any
longer.  While at this, fix an old comment which is no longer valid.  This
should not cause any functional change.
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1582782965-3274-2-git-send-email-anshuman.khandual@arm.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -356,10 +356,12 @@ extern unsigned int kobjsize(const void *objp);
 
 /*
  * Special vmas that are non-mergable, non-mlock()able.
- * Note: mm/huge_memory.c VM_NO_THP depends on this definition.
  */
 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP)
 
+/* This mask prevents VMA from being scanned with khugepaged */
+#define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB)
+
 /* This mask defines which mm->def_flags a process can inherit its parent */
 #define VM_INIT_DEF_MASK	VM_NOHUGEPAGE
 

mm/khugepaged.c

@@ -308,8 +308,6 @@ struct attribute_group khugepaged_attr_group = {
 };
 #endif /* CONFIG_SYSFS */
 
-#define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB)
-
 int hugepage_madvise(struct vm_area_struct *vma,
 		     unsigned long *vm_flags, int advice)
 {