mm: thp: register mm for khugepaged when merging vma for shmem
When merging anonymous page vma, if the size of the vma can fit in at
least one hugepage, the mm will be registered for khugepaged for
collapsing THP in the future.
But it skips shmem vmas. Do so for shmem also, but not for file-private
mappings when merging a vma in order to increase the odds of collapsing
a hugepage via khugepaged.
hugepage_vma_check() sounds like a good fit to do the check. And move
the definition of it before khugepaged_enter_vma_merge() to avoid a
build error.
Link: http://lkml.kernel.org/r/1529697791-6950-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d7b2a4b..22da712 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -397,6 +397,25 @@
return atomic_read(&mm->mm_users) == 0;
}
+static bool hugepage_vma_check(struct vm_area_struct *vma)
+{
+ if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
+ (vma->vm_flags & VM_NOHUGEPAGE) ||
+ test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+ return false;
+ if (shmem_file(vma->vm_file)) {
+ if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
+ return false;
+ return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
+ HPAGE_PMD_NR);
+ }
+ if (!vma->anon_vma || vma->vm_ops)
+ return false;
+ if (is_vma_temporary_stack(vma))
+ return false;
+ return !(vma->vm_flags & VM_NO_KHUGEPAGED);
+}
+
int __khugepaged_enter(struct mm_struct *mm)
{
struct mm_slot *mm_slot;
@@ -434,15 +453,14 @@
unsigned long vm_flags)
{
unsigned long hstart, hend;
- if (!vma->anon_vma)
- /*
- * Not yet faulted in so we will register later in the
- * page fault if needed.
- */
+
+ /*
+ * khugepaged does not yet work on non-shmem files or special
+ * mappings. And file-private shmem THP is not supported.
+ */
+ if (!hugepage_vma_check(vma))
return 0;
- if (vma->vm_ops || (vm_flags & VM_NO_KHUGEPAGED))
- /* khugepaged not yet working on file or special mappings */
- return 0;
+
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
if (hstart < hend)
@@ -819,25 +837,6 @@
}
#endif
-static bool hugepage_vma_check(struct vm_area_struct *vma)
-{
- if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
- (vma->vm_flags & VM_NOHUGEPAGE) ||
- test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
- return false;
- if (shmem_file(vma->vm_file)) {
- if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
- return false;
- return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
- HPAGE_PMD_NR);
- }
- if (!vma->anon_vma || vma->vm_ops)
- return false;
- if (is_vma_temporary_stack(vma))
- return false;
- return !(vma->vm_flags & VM_NO_KHUGEPAGED);
-}
-
/*
* If mmap_sem temporarily dropped, revalidate vma
* before taking mmap_sem.