mm: khugepaged: make hugepage_vma_check() non-static

The hugepage_vma_check() could be reused by khugepaged_enter() and
khugepaged_enter_vma_merge(), but it is static in khugepaged.c.  Make it
non-static and declare it in khugepaged.h.

Link: https://lkml.kernel.org/r/20220510203222.24246-7-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <song@kernel.org>
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>

include/linux/khugepaged.h

@@ -3,8 +3,6 @@
 #define _LINUX_KHUGEPAGED_H
 
 #include <linux/sched/coredump.h> /* MMF_VM_HUGEPAGE */
-#include <linux/shmem_fs.h>
-
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern struct attribute_group khugepaged_attr_group;
@@ -12,6 +10,8 @@ extern struct attribute_group khugepaged_attr_group;
 extern int khugepaged_init(void);
 extern void khugepaged_destroy(void);
 extern int start_stop_khugepaged(void);
+extern bool hugepage_vma_check(struct vm_area_struct *vma,
+			       unsigned long vm_flags);
 extern void __khugepaged_enter(struct mm_struct *mm);
 extern void __khugepaged_exit(struct mm_struct *mm);
 extern void khugepaged_enter_vma_merge(struct vm_area_struct *vma,
@@ -55,13 +55,11 @@ static inline void khugepaged_exit(struct mm_struct *mm)
 static inline void khugepaged_enter(struct vm_area_struct *vma,
 				   unsigned long vm_flags)
 {
-	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
-		if ((khugepaged_always() ||
-		     (shmem_file(vma->vm_file) && shmem_huge_enabled(vma)) ||
-		     (khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) &&
-		    !(vm_flags & VM_NOHUGEPAGE) &&
-		    !test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
+	    khugepaged_enabled()) {
+		if (hugepage_vma_check(vma, vm_flags))
 			__khugepaged_enter(vma->vm_mm);
+	}
 }
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)

mm/khugepaged.c

@@ -437,7 +437,7 @@ static inline int khugepaged_test_exit(struct mm_struct *mm)
 	return atomic_read(&mm->mm_users) == 0;
 }
 
-static bool hugepage_vma_check(struct vm_area_struct *vma,
+bool hugepage_vma_check(struct vm_area_struct *vma,
 			unsigned long vm_flags)
 {
 	if (!transhuge_vma_enabled(vma, vm_flags))
@@ -508,20 +508,13 @@ void __khugepaged_enter(struct mm_struct *mm)
 void khugepaged_enter_vma_merge(struct vm_area_struct *vma,
 			       unsigned long vm_flags)
 {
-	unsigned long hstart, hend;
-
-	/*
-	 * khugepaged only supports read-only files for non-shmem files.
-	 * khugepaged does not yet work on special mappings. And
-	 * file-private shmem THP is not supported.
-	 */
-	if (!hugepage_vma_check(vma, vm_flags))
-		return;
-
-	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
-	hend = vma->vm_end & HPAGE_PMD_MASK;
-	if (hstart < hend)
-		khugepaged_enter(vma, vm_flags);
+	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
+	    khugepaged_enabled() &&
+	    (((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
+	     (vma->vm_end & HPAGE_PMD_MASK))) {
+		if (hugepage_vma_check(vma, vm_flags))
+			__khugepaged_enter(vma->vm_mm);
+	}
 }
 
 void __khugepaged_exit(struct mm_struct *mm)