From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxx Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/khugepaged.c | 53 ++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 27 deletions(-) --- a/mm/khugepaged.c~mm-thp-register-mm-for-khugepaged-when-merging-vma-for-shmem-v3 +++ a/mm/khugepaged.c @@ -397,6 +397,25 @@ static inline int khugepaged_test_exit(s 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 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 **hpag } #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. _
