shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings

Let's wire up existing madvise() hugepage hints for file mappings.

MADV_HUGEPAGE advise shmem to allocate huge page on page fault in the
VMA.  It only has effect if the filesystem is mounted with huge=advise
or huge=within_size.

MADV_NOHUGEPAGE prevents hugepage from being allocated on page fault in
the VMA.  It doesn't prevent a huge page from being allocated by other
means, i.e.  page fault into different mapping or write(2) into file.

Link: http://lkml.kernel.org/r/1466021202-61880-31-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0f58460..5eba978 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1830,7 +1830,7 @@ spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
        return NULL;
 }
 
-#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
+#define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
 
 int hugepage_madvise(struct vm_area_struct *vma,
                     unsigned long *vm_flags, int advice)
@@ -1846,11 +1846,6 @@ int hugepage_madvise(struct vm_area_struct *vma,
                if (mm_has_pgste(vma->vm_mm))
                        return 0;
 #endif
-               /*
-                * Be somewhat over-protective like KSM for now!
-                */
-               if (*vm_flags & VM_NO_THP)
-                       return -EINVAL;
                *vm_flags &= ~VM_NOHUGEPAGE;
                *vm_flags |= VM_HUGEPAGE;
                /*
@@ -1858,15 +1853,11 @@ int hugepage_madvise(struct vm_area_struct *vma,
                 * register it here without waiting a page fault that
                 * may not happen any time soon.
                 */
-               if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
+               if (!(*vm_flags & VM_NO_KHUGEPAGED) &&
+                               khugepaged_enter_vma_merge(vma, *vm_flags))
                        return -ENOMEM;
                break;
        case MADV_NOHUGEPAGE:
-               /*
-                * Be somewhat over-protective like KSM for now!
-                */
-               if (*vm_flags & VM_NO_THP)
-                       return -EINVAL;
                *vm_flags &= ~VM_HUGEPAGE;
                *vm_flags |= VM_NOHUGEPAGE;
                /*
@@ -1974,7 +1965,7 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
                 * page fault if needed.
                 */
                return 0;
-       if (vma->vm_ops || (vm_flags & VM_NO_THP))
+       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;
@@ -2366,7 +2357,7 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
                return false;
        if (is_vma_temporary_stack(vma))
                return false;
-       return !(vma->vm_flags & VM_NO_THP);
+       return !(vma->vm_flags & VM_NO_KHUGEPAGED);
 }
 
 /*

diff --git a/mm/shmem.c b/mm/shmem.c
index 302ae4a..f19b6b4 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -101,6 +101,8 @@ struct shmem_falloc {
 enum sgp_type {
        SGP_READ,       /* don't exceed i_size, don't allocate page */
        SGP_CACHE,      /* don't exceed i_size, may allocate page */
+       SGP_NOHUGE,     /* like SGP_CACHE, but no huge pages */
+       SGP_HUGE,       /* like SGP_CACHE, huge pages preferred */
        SGP_WRITE,      /* may exceed i_size, may allocate !Uptodate page */
        SGP_FALLOC,     /* like SGP_WRITE, but make existing page Uptodate */
 };
@@ -1409,6 +1411,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
        struct mem_cgroup *memcg;
        struct page *page;
        swp_entry_t swap;
+       enum sgp_type sgp_huge = sgp;
        pgoff_t hindex = index;
        int error;
        int once = 0;
@@ -1416,6 +1419,8 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 
        if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
                return -EFBIG;
+       if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
+               sgp = SGP_CACHE;
 repeat:
        swap.val = 0;
        page = find_lock_entry(mapping, index);
@@ -1534,7 +1539,7 @@ repeat:
                /* shmem_symlink() */
                if (mapping->a_ops != &shmem_aops)
                        goto alloc_nohuge;
-               if (shmem_huge == SHMEM_HUGE_DENY)
+               if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
                        goto alloc_nohuge;
                if (shmem_huge == SHMEM_HUGE_FORCE)
                        goto alloc_huge;
@@ -1551,7 +1556,9 @@ repeat:
                                goto alloc_huge;
                        /* fallthrough */
                case SHMEM_HUGE_ADVISE:
-                       /* TODO: wire up fadvise()/madvise() */
+                       if (sgp_huge == SGP_HUGE)
+                               goto alloc_huge;
+                       /* TODO: implement fadvise() hints */
                        goto alloc_nohuge;
                }
 
@@ -1680,6 +1687,7 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
        struct inode *inode = file_inode(vma->vm_file);
        gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
+       enum sgp_type sgp;
        int error;
        int ret = VM_FAULT_LOCKED;
 
@@ -1741,7 +1749,13 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
                spin_unlock(&inode->i_lock);
        }
 
-       error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE,
+       sgp = SGP_CACHE;
+       if (vma->vm_flags & VM_HUGEPAGE)
+               sgp = SGP_HUGE;
+       else if (vma->vm_flags & VM_NOHUGEPAGE)
+               sgp = SGP_NOHUGE;
+
+       error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
                                  gfp, vma->vm_mm, &ret);
        if (error)
                return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);