From c2231020ea7b53d486395dbd8d3216e0dd1fc7ee Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Fri, 17 Aug 2018 15:45:26 -0700 Subject: 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 Acked-by: Kirill A. Shutemov Cc: Hugh Dickins Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/khugepaged.c | 53 ++++++++++++++++++++++++++--------------------------- 1 file changed, 26 insertions(+), 27 deletions(-) (limited to 'mm/khugepaged.c') diff --git a/mm/khugepaged.c b/mm/khugepaged.c index d7b2a4bf8671..22da712022de 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -397,6 +397,25 @@ 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) +{ + 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 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma, 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. - */ - return 0; - if (vma->vm_ops || (vm_flags & VM_NO_KHUGEPAGED)) - /* khugepaged not yet working on file or special mappings */ + + /* + * 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; + hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK; if (hstart < hend) @@ -819,25 +837,6 @@ khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) } #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. -- cgit v1.2.3