[PATCHv3 28/41] mm, hugetlb: switch hugetlbfs to multi-order radix-tree entries

Kirill A. Shutemov
2016-09-15T11:55:10Z

From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Currently, hugetlb pages are linked to page cache on the basis of hugepage
offset (derived from vma_hugecache_offset()) for historical reason, which
doesn't match to the generic usage of page cache and requires some routines
to covert page offset <=> hugepage offset in common path. This patch
adjusts code for multi-order radix-tree to avoid the situation.

Main change is on the behavior of page->index for hugetlbfs. Before this
patch, it represented hugepage offset, but with this patch it represents
page offset. So index-related code have to be updated.
Note that hugetlb_fault_mutex_hash() and reservation region handling are
still working with hugepage offset.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
[kirill.shutemov@linux.intel.com: reject fixed]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
fs/hugetlbfs/inode.c | 22 ++++++++++------------
include/linux/pagemap.h | 10 +---------
mm/filemap.c | 30 ++++++++++++++++++------------
mm/hugetlb.c | 19 ++++++-------------
4 files changed, 35 insertions(+), 46 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 4ea71eba40a5..fc918c0e33e9 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -388,8 +388,8 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
{
struct hstate *h = hstate_inode(inode);
struct address_space *mapping = &inode->i_data;
- const pgoff_t start = lstart >> huge_page_shift(h);
- const pgoff_t end = lend >> huge_page_shift(h);
+ const pgoff_t start = lstart >> PAGE_SHIFT;
+ const pgoff_t end = lend >> PAGE_SHIFT;
struct vm_area_struct pseudo_vma;
struct pagevec pvec;
pgoff_t next;
@@ -447,8 +447,7 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,

i_mmap_lock_write(mapping);
hugetlb_vmdelete_list(&mapping->i_mmap,
- next * pages_per_huge_page(h),
- (next + 1) * pages_per_huge_page(h));
+ next, next + 1);
i_mmap_unlock_write(mapping);
}

@@ -467,7 +466,8 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
freed++;
if (!truncate_op) {
if (unlikely(hugetlb_unreserve_pages(inode,
- next, next + 1, 1)))
+ (next) << huge_page_order(h),
+ (next + 1) << huge_page_order(h), 1)))
hugetlb_fix_reserve_counts(inode,
rsv_on_error);
}
@@ -552,8 +552,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
struct hstate *h = hstate_inode(inode);
struct vm_area_struct pseudo_vma;
struct mm_struct *mm = current->mm;
- loff_t hpage_size = huge_page_size(h);
- unsigned long hpage_shift = huge_page_shift(h);
pgoff_t start, index, end;
int error;
u32 hash;
@@ -569,8 +567,8 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
* For this range, start is rounded down and end is rounded up
* as well as being converted to page offsets.
*/
- start = offset >> hpage_shift;
- end = (offset + len + hpage_size - 1) >> hpage_shift;
+ start = offset >> PAGE_SHIFT;
+ end = (offset + len + huge_page_size(h) - 1) >> PAGE_SHIFT;

inode_lock(inode);

@@ -588,7 +586,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
pseudo_vma.vm_file = file;

- for (index = start; index < end; index++) {
+ for (index = start; index < end; index += pages_per_huge_page(h)) {
/*
* This is supposed to be the vaddr where the page is being
* faulted in, but we have no vaddr here.
@@ -609,10 +607,10 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
}

/* Set numa allocation policy based on index */
- hugetlb_set_vma_policy(&pseudo_vma, inode, index);
+ hugetlb_set_vma_policy(&pseudo_vma, inode, index >> huge_page_order(h));

/* addr is the offset within the file (zero based) */
- addr = index * hpage_size;
+ addr = index << PAGE_SHIFT & ~huge_page_mask(h);

/* mutex taken here, fault path and hole punch */
hash = hugetlb_fault_mutex_hash(h, mm, &pseudo_vma, mapping,
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 4d6e9aec2d1f..645dcb72ca0f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -380,15 +380,11 @@ static inline struct page *read_mapping_page(struct address_space *mapping,

/*
* Get the offset in PAGE_SIZE.
- * (TODO: hugepage should have ->index in PAGE_SIZE)
*/
static inline pgoff_t page_to_pgoff(struct page *page)
{
pgoff_t pgoff;

- if (unlikely(PageHeadHuge(page)))
- return page->index << compound_order(page);
-
if (likely(!PageTransTail(page)))
return page->index;

@@ -414,15 +410,11 @@ static inline loff_t page_file_offset(struct page *page)
return ((loff_t)page_file_index(page)) << PAGE_SHIFT;
}

-extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
- unsigned long address);
-
static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
unsigned long address)
{
pgoff_t pgoff;
- if (unlikely(is_vm_hugetlb_page(vma)))
- return linear_hugepage_index(vma, address);
+
pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
pgoff += vma->vm_pgoff;
return pgoff;
diff --git a/mm/filemap.c b/mm/filemap.c
index 53da93156e60..61d375d7f93e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -114,7 +114,7 @@ static void page_cache_tree_delete(struct address_space *mapping,
struct page *page, void *shadow)
{
struct radix_tree_node *node;
- int nr = PageHuge(page) ? 1 : hpage_nr_pages(page);
+ int nr = hpage_nr_pages(page);

VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(PageTail(page), page);
@@ -668,7 +668,7 @@ static int __add_to_page_cache_locked(struct page *page,
page->index = offset;

spin_lock_irq(&mapping->tree_lock);
- if (PageTransHuge(page)) {
+ if (PageCompound(page)) {
struct radix_tree_iter iter;
void **slot;
void *p;
@@ -677,7 +677,7 @@ static int __add_to_page_cache_locked(struct page *page,

/* Wipe shadow entires */
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, offset) {
- if (iter.index >= offset + HPAGE_PMD_NR)
+ if (iter.index >= offset + hpage_nr_pages(page))
break;

p = radix_tree_deref_slot_protected(slot,
@@ -699,10 +699,15 @@ static int __add_to_page_cache_locked(struct page *page,
compound_order(page), page);

if (!error) {
- count_vm_event(THP_FILE_ALLOC);
- mapping->nrpages += HPAGE_PMD_NR;
- *shadowp = NULL;
- __inc_node_page_state(page, NR_FILE_THPS);
+ if (hugetlb) {
+ mapping->nrpages += 1 << compound_order(page);
+ } else if (PageTransHuge(page)) {
+ count_vm_event(THP_FILE_ALLOC);
+ mapping->nrpages += HPAGE_PMD_NR;
+ *shadowp = NULL;
+ __inc_node_page_state(page, NR_FILE_THPS);
+ } else
+ BUG();
}
} else {
error = page_cache_tree_insert(mapping, page, shadowp);
@@ -1144,9 +1149,9 @@ repeat:
}

/* For multi-order entries, find relevant subpage */
- if (PageTransHuge(page)) {
+ if (PageCompound(page)) {
VM_BUG_ON(offset - page->index < 0);
- VM_BUG_ON(offset - page->index >= HPAGE_PMD_NR);
+ VM_BUG_ON(offset - page->index >= 1 << compound_order(page));
page += offset - page->index;
}
}
@@ -1514,16 +1519,17 @@ repeat:
}

/* For multi-order entries, find relevant subpage */
- if (PageTransHuge(page)) {
+ if (PageCompound(page)) {
VM_BUG_ON(index - page->index < 0);
- VM_BUG_ON(index - page->index >= HPAGE_PMD_NR);
+ VM_BUG_ON(index - page->index >=
+ 1 << compound_order(page));
page += index - page->index;
}

pages[ret] = page;
if (++ret == nr_pages)
break;
- if (!PageTransCompound(page))
+ if (PageHuge(page) || !PageTransCompound(page))
continue;
for (refs = 0; ret < nr_pages &&
(index + 1) % HPAGE_PMD_NR;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 87e11d8ad536..a50e20553265 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -622,13 +622,6 @@ static pgoff_t vma_hugecache_offset(struct hstate *h,
(vma->vm_pgoff >> huge_page_order(h));
}

-pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
- unsigned long address)
-{
- return vma_hugecache_offset(hstate_vma(vma), vma, address);
-}
-EXPORT_SYMBOL_GPL(linear_hugepage_index);
-
/*
* Return the size of the pages allocated when backing a VMA. In the majority
* cases this will be same size as used by the page table entries.
@@ -3491,7 +3484,7 @@ static struct page *hugetlbfs_pagecache_page(struct hstate *h,
pgoff_t idx;

mapping = vma->vm_file->f_mapping;
- idx = vma_hugecache_offset(h, vma, address);
+ idx = linear_page_index(vma, address);

return find_lock_page(mapping, idx);
}
@@ -3508,7 +3501,7 @@ static bool hugetlbfs_pagecache_present(struct hstate *h,
struct page *page;

mapping = vma->vm_file->f_mapping;
- idx = vma_hugecache_offset(h, vma, address);
+ idx = linear_page_index(vma, address);

page = find_get_page(mapping, idx);
if (page)
@@ -3563,7 +3556,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
retry:
page = find_lock_page(mapping, idx);
if (!page) {
- size = i_size_read(mapping->host) >> huge_page_shift(h);
+ size = i_size_read(mapping->host) >> PAGE_SHIFT;
if (idx >= size)
goto out;
page = alloc_huge_page(vma, address, 0);
@@ -3625,7 +3618,7 @@ retry:

ptl = huge_pte_lockptr(h, mm, ptep);
spin_lock(ptl);
- size = i_size_read(mapping->host) >> huge_page_shift(h);
+ size = i_size_read(mapping->host) >> PAGE_SHIFT;
if (idx >= size)
goto backout;

@@ -3672,7 +3665,7 @@ u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm,

if (vma->vm_flags & VM_SHARED) {
key[0] = (unsigned long) mapping;
- key[1] = idx;
+ key[1] = idx >> huge_page_order(h);
} else {
key[0] = (unsigned long) mm;
key[1] = address >> huge_page_shift(h);
@@ -3728,7 +3721,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
}

mapping = vma->vm_file->f_mapping;
- idx = vma_hugecache_offset(h, vma, address);
+ idx = linear_page_index(vma, address);

/*
* Serialize hugepage allocation and instantiation, so that we don't