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shmem: add huge pages support

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Here's basic implementation of huge pages support for shmem/tmpfs.

It's all pretty streight-forward:

  - shmem_getpage() allcoates huge page if it can and try to inserd into
    radix tree with shmem_add_to_page_cache();

  - shmem_add_to_page_cache() puts the page onto radix-tree if there's
    space for it;

  - shmem_undo_range() removes huge pages, if it fully within range.
    Partial truncate of huge pages zero out this part of THP.

    This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE)
    behaviour. As we don't really create hole in this case,
    lseek(SEEK_HOLE) may have inconsistent results depending what
    pages happened to be allocated.

  - no need to change shmem_fault: core-mm will map an compound page as
    huge if VMA is suitable;

Link: http://lkml.kernel.org/r/1466021202-61880-30-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>
This commit is contained in:
Kirill A. Shutemov 2016-07-26 15:26:18 -07:00 • committed by Linus Torvalds
parent c01d5b3007
commit 800d8c63b2
9 changed files with 331 additions and 70 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
include/linux/huge_mm.h
View file

@ -156,6 +156,8 @@ void put_huge_zero_page(void);
#define transparent_hugepage_enabled(__vma) 0
static inline void prep_transhuge_page(struct page *page) {}
#define transparent_hugepage_flags 0UL
static inline int
split_huge_page_to_list(struct page *page, struct list_head *list)

3
include/linux/shmem_fs.h
View file

@ -71,6 +71,9 @@ static inline struct page *shmem_read_mapping_page(
mapping_gfp_mask(mapping));
}
extern bool shmem_charge(struct inode *inode, long pages);
extern void shmem_uncharge(struct inode *inode, long pages);
#ifdef CONFIG_TMPFS
extern int shmem_add_seals(struct file *file, unsigned int seals);

7
mm/filemap.c
View file

@ -219,8 +219,13 @@ void __delete_from_page_cache(struct page *page, void *shadow)
/* hugetlb pages do not participate in page cache accounting. */
if (!PageHuge(page))
__mod_zone_page_state(page_zone(page), NR_FILE_PAGES, -nr);
if (PageSwapBacked(page))
if (PageSwapBacked(page)) {
__mod_zone_page_state(page_zone(page), NR_SHMEM, -nr);
if (PageTransHuge(page))
__dec_zone_page_state(page, NR_SHMEM_THPS);
} else {
VM_BUG_ON_PAGE(PageTransHuge(page) && !PageHuge(page), page);
}
/*
* At this point page must be either written or cleaned by truncate.

2
mm/huge_memory.c
View file

@ -3316,6 +3316,8 @@ static void __split_huge_page(struct page *page, struct list_head *list,
if (head[i].index >= end) {
__ClearPageDirty(head + i);
__delete_from_page_cache(head + i, NULL);
if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
shmem_uncharge(head->mapping->host, 1);
put_page(head + i);
}
}

2
mm/memory.c
View file

@ -1142,7 +1142,7 @@ again:
* unmap shared but keep private pages.
*/
if (details->check_mapping &&
details->check_mapping != page->mapping)
details->check_mapping != page_rmapping(page))
continue;
}
ptent = ptep_get_and_clear_full(mm, addr, pte,

2
mm/mempolicy.c
View file

@ -531,7 +531,7 @@ retry:
nid = page_to_nid(page);
if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
continue;
if (PageTransCompound(page) && PageAnon(page)) {
if (PageTransCompound(page)) {
get_page(page);
pte_unmap_unlock(pte, ptl);
lock_page(page);

1
mm/page-writeback.c
View file

@ -2563,6 +2563,7 @@ int set_page_dirty(struct page *page)
{
struct address_space *mapping = page_mapping(page);
page = compound_head(page);
if (likely(mapping)) {
int (*spd)(struct page *) = mapping->a_ops->set_page_dirty;
/*

380
mm/shmem.c
View file

@ -173,10 +173,13 @@ static inline int shmem_reacct_size(unsigned long flags,
* shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
* so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
*/
static inline int shmem_acct_block(unsigned long flags)
static inline int shmem_acct_block(unsigned long flags, long pages)
{
return (flags & VM_NORESERVE) ?
security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_SIZE)) : 0;
if (!(flags & VM_NORESERVE))
return 0;
return security_vm_enough_memory_mm(current->mm,
pages * VM_ACCT(PAGE_SIZE));
}
static inline void shmem_unacct_blocks(unsigned long flags, long pages)
@ -249,6 +252,51 @@ static void shmem_recalc_inode(struct inode *inode)
}
}
bool shmem_charge(struct inode *inode, long pages)
{
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
if (shmem_acct_block(info->flags, pages))
return false;
spin_lock(&info->lock);
info->alloced += pages;
inode->i_blocks += pages * BLOCKS_PER_PAGE;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
inode->i_mapping->nrpages += pages;
if (!sbinfo->max_blocks)
return true;
if (percpu_counter_compare(&sbinfo->used_blocks,
sbinfo->max_blocks - pages) > 0) {
inode->i_mapping->nrpages -= pages;
spin_lock(&info->lock);
info->alloced -= pages;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
return false;
}
percpu_counter_add(&sbinfo->used_blocks, pages);
return true;
}
void shmem_uncharge(struct inode *inode, long pages)
{
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
spin_lock(&info->lock);
info->alloced -= pages;
inode->i_blocks -= pages * BLOCKS_PER_PAGE;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
if (sbinfo->max_blocks)
percpu_counter_sub(&sbinfo->used_blocks, pages);
}
/*
* Replace item expected in radix tree by a new item, while holding tree lock.
*/
@ -376,30 +424,57 @@ static int shmem_add_to_page_cache(struct page *page,
struct address_space *mapping,
pgoff_t index, void *expected)
{
int error;
int error, nr = hpage_nr_pages(page);
VM_BUG_ON_PAGE(PageTail(page), page);
VM_BUG_ON_PAGE(index != round_down(index, nr), page);
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
VM_BUG_ON(expected && PageTransHuge(page));
get_page(page);
page_ref_add(page, nr);
page->mapping = mapping;
page->index = index;
spin_lock_irq(&mapping->tree_lock);
if (!expected)
if (PageTransHuge(page)) {
void __rcu **results;
pgoff_t idx;
int i;
error = 0;
if (radix_tree_gang_lookup_slot(&mapping->page_tree,
&results, &idx, index, 1) &&
idx < index + HPAGE_PMD_NR) {
error = -EEXIST;
}
if (!error) {
for (i = 0; i < HPAGE_PMD_NR; i++) {
error = radix_tree_insert(&mapping->page_tree,
index + i, page + i);
VM_BUG_ON(error);
}
count_vm_event(THP_FILE_ALLOC);
}
} else if (!expected) {
error = radix_tree_insert(&mapping->page_tree, index, page);
else
} else {
error = shmem_radix_tree_replace(mapping, index, expected,
page);
}
if (!error) {
mapping->nrpages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
__inc_zone_page_state(page, NR_SHMEM);
mapping->nrpages += nr;
if (PageTransHuge(page))
__inc_zone_page_state(page, NR_SHMEM_THPS);
__mod_zone_page_state(page_zone(page), NR_FILE_PAGES, nr);
__mod_zone_page_state(page_zone(page), NR_SHMEM, nr);
spin_unlock_irq(&mapping->tree_lock);
} else {
page->mapping = NULL;
spin_unlock_irq(&mapping->tree_lock);
put_page(page);
page_ref_sub(page, nr);
}
return error;
}
@ -412,6 +487,8 @@ static void shmem_delete_from_page_cache(struct page *page, void *radswap)
struct address_space *mapping = page->mapping;
int error;
VM_BUG_ON_PAGE(PageCompound(page), page);
spin_lock_irq(&mapping->tree_lock);
error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
page->mapping = NULL;
@ -591,10 +668,33 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
continue;
}
VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
if (!trylock_page(page))
continue;
if (PageTransTail(page)) {
/* Middle of THP: zero out the page */
clear_highpage(page);
unlock_page(page);
continue;
} else if (PageTransHuge(page)) {
if (index == round_down(end, HPAGE_PMD_NR)) {
/*
* Range ends in the middle of THP:
* zero out the page
*/
clear_highpage(page);
unlock_page(page);
continue;
}
index += HPAGE_PMD_NR - 1;
i += HPAGE_PMD_NR - 1;
}
if (!unfalloc || !PageUptodate(page)) {
if (page->mapping == mapping) {
VM_BUG_ON_PAGE(PageTail(page), page);
if (page_mapping(page) == mapping) {
VM_BUG_ON_PAGE(PageWriteback(page), page);
truncate_inode_page(mapping, page);
}
@ -670,8 +770,36 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
}
lock_page(page);
if (PageTransTail(page)) {
/* Middle of THP: zero out the page */
clear_highpage(page);
unlock_page(page);
/*
* Partial thp truncate due 'start' in middle
* of THP: don't need to look on these pages
* again on !pvec.nr restart.
*/
if (index != round_down(end, HPAGE_PMD_NR))
start++;
continue;
} else if (PageTransHuge(page)) {
if (index == round_down(end, HPAGE_PMD_NR)) {
/*
* Range ends in the middle of THP:
* zero out the page
*/
clear_highpage(page);
unlock_page(page);
continue;
}
index += HPAGE_PMD_NR - 1;
i += HPAGE_PMD_NR - 1;
}
if (!unfalloc || !PageUptodate(page)) {
if (page->mapping == mapping) {
VM_BUG_ON_PAGE(PageTail(page), page);
if (page_mapping(page) == mapping) {
VM_BUG_ON_PAGE(PageWriteback(page), page);
truncate_inode_page(mapping, page);
} else {
@ -929,6 +1057,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
swp_entry_t swap;
pgoff_t index;
VM_BUG_ON_PAGE(PageCompound(page), page);
BUG_ON(!PageLocked(page));
mapping = page->mapping;
index = page->index;
@ -1065,24 +1194,63 @@ static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
#define vm_policy vm_private_data
#endif
static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
struct shmem_inode_info *info, pgoff_t index)
{
/* Create a pseudo vma that just contains the policy */
vma->vm_start = 0;
/* Bias interleave by inode number to distribute better across nodes */
vma->vm_pgoff = index + info->vfs_inode.i_ino;
vma->vm_ops = NULL;
vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
}
static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
{
/* Drop reference taken by mpol_shared_policy_lookup() */
mpol_cond_put(vma->vm_policy);
}
static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct vm_area_struct pvma;
struct page *page;
/* Create a pseudo vma that just contains the policy */
pvma.vm_start = 0;
/* Bias interleave by inode number to distribute better across nodes */
pvma.vm_pgoff = index + info->vfs_inode.i_ino;
pvma.vm_ops = NULL;
pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
shmem_pseudo_vma_init(&pvma, info, index);
page = swapin_readahead(swap, gfp, &pvma, 0);
shmem_pseudo_vma_destroy(&pvma);
/* Drop reference taken by mpol_shared_policy_lookup() */
mpol_cond_put(pvma.vm_policy);
return page;
}
static struct page *shmem_alloc_hugepage(gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct vm_area_struct pvma;
struct inode *inode = &info->vfs_inode;
struct address_space *mapping = inode->i_mapping;
pgoff_t idx, hindex = round_down(index, HPAGE_PMD_NR);
void __rcu **results;
struct page *page;
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
return NULL;
rcu_read_lock();
if (radix_tree_gang_lookup_slot(&mapping->page_tree, &results, &idx,
hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
rcu_read_unlock();
return NULL;
}
rcu_read_unlock();
shmem_pseudo_vma_init(&pvma, info, hindex);
page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
shmem_pseudo_vma_destroy(&pvma);
if (page)
prep_transhuge_page(page);
return page;
}
@ -1092,23 +1260,51 @@ static struct page *shmem_alloc_page(gfp_t gfp,
struct vm_area_struct pvma;
struct page *page;
/* Create a pseudo vma that just contains the policy */
pvma.vm_start = 0;
/* Bias interleave by inode number to distribute better across nodes */
pvma.vm_pgoff = index + info->vfs_inode.i_ino;
pvma.vm_ops = NULL;
pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
shmem_pseudo_vma_init(&pvma, info, index);
page = alloc_page_vma(gfp, &pvma, 0);
shmem_pseudo_vma_destroy(&pvma);
page = alloc_pages_vma(gfp, 0, &pvma, 0, numa_node_id(), false);
return page;
}
static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
struct shmem_inode_info *info, struct shmem_sb_info *sbinfo,
pgoff_t index, bool huge)
{
struct page *page;
int nr;
int err = -ENOSPC;
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
huge = false;
nr = huge ? HPAGE_PMD_NR : 1;
if (shmem_acct_block(info->flags, nr))
goto failed;
if (sbinfo->max_blocks) {
if (percpu_counter_compare(&sbinfo->used_blocks,
sbinfo->max_blocks - nr) > 0)
goto unacct;
percpu_counter_add(&sbinfo->used_blocks, nr);
}
if (huge)
page = shmem_alloc_hugepage(gfp, info, index);
else
page = shmem_alloc_page(gfp, info, index);
if (page) {
__SetPageLocked(page);
__SetPageSwapBacked(page);
return page;
}
/* Drop reference taken by mpol_shared_policy_lookup() */
mpol_cond_put(pvma.vm_policy);
return page;
err = -ENOMEM;
if (sbinfo->max_blocks)
percpu_counter_add(&sbinfo->used_blocks, -nr);
unacct:
shmem_unacct_blocks(info->flags, nr);
failed:
return ERR_PTR(err);
}
/*
@ -1213,6 +1409,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
struct mem_cgroup *memcg;
struct page *page;
swp_entry_t swap;
pgoff_t hindex = index;
int error;
int once = 0;
int alloced = 0;
@ -1334,47 +1531,74 @@ repeat:
swap_free(swap);
} else {
if (shmem_acct_block(info->flags)) {
error = -ENOSPC;
goto failed;
}
if (sbinfo->max_blocks) {
if (percpu_counter_compare(&sbinfo->used_blocks,
sbinfo->max_blocks) >= 0) {
error = -ENOSPC;
goto unacct;
}
percpu_counter_inc(&sbinfo->used_blocks);
/* shmem_symlink() */
if (mapping->a_ops != &shmem_aops)
goto alloc_nohuge;
if (shmem_huge == SHMEM_HUGE_DENY)
goto alloc_nohuge;
if (shmem_huge == SHMEM_HUGE_FORCE)
goto alloc_huge;
switch (sbinfo->huge) {
loff_t i_size;
pgoff_t off;
case SHMEM_HUGE_NEVER:
goto alloc_nohuge;
case SHMEM_HUGE_WITHIN_SIZE:
off = round_up(index, HPAGE_PMD_NR);
i_size = round_up(i_size_read(inode), PAGE_SIZE);
if (i_size >= HPAGE_PMD_SIZE &&
i_size >> PAGE_SHIFT >= off)
goto alloc_huge;
/* fallthrough */
case SHMEM_HUGE_ADVISE:
/* TODO: wire up fadvise()/madvise() */
goto alloc_nohuge;
}
page = shmem_alloc_page(gfp, info, index);
if (!page) {
error = -ENOMEM;
goto decused;
alloc_huge:
page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
index, true);
if (IS_ERR(page)) {
alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
index, false);
}
if (IS_ERR(page)) {
error = PTR_ERR(page);
page = NULL;
goto failed;
}
if (PageTransHuge(page))
hindex = round_down(index, HPAGE_PMD_NR);
else
hindex = index;
if (sgp == SGP_WRITE)
__SetPageReferenced(page);
error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
false);
PageTransHuge(page));
if (error)
goto decused;
error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
goto unacct;
error = radix_tree_maybe_preload_order(gfp & GFP_RECLAIM_MASK,
compound_order(page));
if (!error) {
error = shmem_add_to_page_cache(page, mapping, index,
error = shmem_add_to_page_cache(page, mapping, hindex,
NULL);
radix_tree_preload_end();
}
if (error) {
mem_cgroup_cancel_charge(page, memcg, false);
goto decused;
mem_cgroup_cancel_charge(page, memcg,
PageTransHuge(page));
goto unacct;
}
mem_cgroup_commit_charge(page, memcg, false, false);
mem_cgroup_commit_charge(page, memcg, false,
PageTransHuge(page));
lru_cache_add_anon(page);
spin_lock(&info->lock);
info->alloced++;
inode->i_blocks += BLOCKS_PER_PAGE;
info->alloced += 1 << compound_order(page);
inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
alloced = true;
@ -1390,10 +1614,15 @@ clear:
* but SGP_FALLOC on a page fallocated earlier must initialize
* it now, lest undo on failure cancel our earlier guarantee.
*/
if (sgp != SGP_WRITE) {
clear_highpage(page);
flush_dcache_page(page);
SetPageUptodate(page);
if (sgp != SGP_WRITE && !PageUptodate(page)) {
struct page *head = compound_head(page);
int i;
for (i = 0; i < (1 << compound_order(head)); i++) {
clear_highpage(head + i);
flush_dcache_page(head + i);
}
SetPageUptodate(head);
}
}
@ -1410,17 +1639,23 @@ clear:
error = -EINVAL;
goto unlock;
}
*pagep = page;
*pagep = page + index - hindex;
return 0;
/*
* Error recovery.
*/
decused:
if (sbinfo->max_blocks)
percpu_counter_add(&sbinfo->used_blocks, -1);
unacct:
shmem_unacct_blocks(info->flags, 1);
if (sbinfo->max_blocks)
percpu_counter_sub(&sbinfo->used_blocks,
1 << compound_order(page));
shmem_unacct_blocks(info->flags, 1 << compound_order(page));
if (PageTransHuge(page)) {
unlock_page(page);
put_page(page);
goto alloc_nohuge;
}
failed:
if (swap.val && !shmem_confirm_swap(mapping, index, swap))
error = -EEXIST;
@ -1758,12 +1993,23 @@ shmem_write_end(struct file *file, struct address_space *mapping,
i_size_write(inode, pos + copied);
if (!PageUptodate(page)) {
struct page *head = compound_head(page);
if (PageTransCompound(page)) {
int i;
for (i = 0; i < HPAGE_PMD_NR; i++) {
if (head + i == page)
continue;
clear_highpage(head + i);
flush_dcache_page(head + i);
}
}
if (copied < PAGE_SIZE) {
unsigned from = pos & (PAGE_SIZE - 1);
zero_user_segments(page, 0, from,
from + copied, PAGE_SIZE);
}
SetPageUptodate(page);
SetPageUptodate(head);
}
set_page_dirty(page);
unlock_page(page);

2
mm/swap.c
View file

@ -292,6 +292,7 @@ static bool need_activate_page_drain(int cpu)
void activate_page(struct page *page)
{
page = compound_head(page);
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
@ -316,6 +317,7 @@ void activate_page(struct page *page)
{
struct zone *zone = page_zone(page);
page = compound_head(page);
spin_lock_irq(&zone->lru_lock);
__activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
spin_unlock_irq(&zone->lru_lock);