[patch 4/5] mm + fs: provide refault distance to page cache instantiations

From: Johannes Weiner
Date: Tue May 01 2012 - 04:43:32 EST

The page allocator needs to be given the non-residency information
stored in the page cache at the time the page is faulted back in.

Every site that does a find_or_create()-style allocation is converted
to pass this refault information to the page_cache_alloc() family of
functions, which in turn passes it down to the page allocator via
current->refault_distance.

XXX: Pages are charged to memory cgroups only when being added to the
page cache, and, in case of multi-page reads, allocation and addition
happen in separate batches. To communicate the individual refault
distance to the memory controller, the refault distance is stored in
page->private between allocation and add_to_page_cache(). memcg does
not do anything with it yet, though, but it will use it when charging
requires reclaiming (hard limit reclaim).

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
fs/btrfs/compression.c | 8 +++--
fs/cachefiles/rdwr.c | 26 +++++++++-----
fs/ceph/xattr.c | 2 +-
fs/logfs/readwrite.c | 9 +++--
fs/ntfs/file.c | 11 ++++--
fs/splice.c | 10 +++--
include/linux/pagemap.h | 28 ++++++++++-----
include/linux/sched.h | 1 +
include/linux/swap.h | 6 +++
mm/filemap.c | 84 ++++++++++++++++++++++++++++++++---------------
mm/readahead.c | 7 +++-
net/ceph/messenger.c | 2 +-
net/ceph/pagelist.c | 4 +-
net/ceph/pagevec.c | 2 +-
14 files changed, 134 insertions(+), 66 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index a0594c9..dc57e09 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -464,6 +464,8 @@ static noinline int add_ra_bio_pages(struct inode *inode,
end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;

while (last_offset < compressed_end) {
+ unsigned long distance;
+
pg_index = last_offset >> PAGE_CACHE_SHIFT;

if (pg_index > end_index)
@@ -478,12 +480,12 @@ static noinline int add_ra_bio_pages(struct inode *inode,
break;
goto next;
}
-
+ distance = workingset_refault_distance(page);
page = __page_cache_alloc(mapping_gfp_mask(mapping) &
- ~__GFP_FS);
+ ~__GFP_FS, distance);
if (!page)
break;
-
+ set_page_private(page, distance);
if (add_to_page_cache_lru(page, mapping, pg_index,
GFP_NOFS)) {
page_cache_release(page);
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index 0e3c092..359be1f 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -12,6 +12,7 @@
#include <linux/mount.h>
#include <linux/slab.h>
#include <linux/file.h>
+#include <linux/swap.h>
#include "internal.h"

/*
@@ -253,16 +254,18 @@ static int cachefiles_read_backing_file_one(struct cachefiles_object *object,
newpage = NULL;

for (;;) {
- backpage = find_get_page(bmapping, netpage->index);
- if (backpage)
- goto backing_page_already_present;
+ unsigned long distance;

+ backpage = __find_get_page(bmapping, netpage->index);
+ if (backpage && !radix_tree_exceptional_entry(backpage))
+ goto backing_page_already_present;
+ distance = workingset_refault_distance(backpage);
if (!newpage) {
- newpage = page_cache_alloc_cold(bmapping);
+ newpage = page_cache_alloc_cold(bmapping, distance);
if (!newpage)
goto nomem_monitor;
}
-
+ set_page_private(newpage, distance);
ret = add_to_page_cache(newpage, bmapping,
netpage->index, GFP_KERNEL);
if (ret == 0)
@@ -495,16 +498,19 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
}

for (;;) {
- backpage = find_get_page(bmapping, netpage->index);
- if (backpage)
- goto backing_page_already_present;
+ unsigned long distance;

+ backpage = __find_get_page(bmapping, netpage->index);
+ if (backpage && !radix_tree_exceptional_entry(backpage))
+ goto backing_page_already_present;
+ distance = workingset_refault_distance(backpage);
if (!newpage) {
- newpage = page_cache_alloc_cold(bmapping);
+ newpage = page_cache_alloc_cold(bmapping,
+ distance);
if (!newpage)
goto nomem;
}
-
+ set_page_private(newpage, distance);
ret = add_to_page_cache(newpage, bmapping,
netpage->index, GFP_KERNEL);
if (ret == 0)
diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index a76f697..26e85d1 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -647,7 +647,7 @@ static int ceph_sync_setxattr(struct dentry *dentry, const char *name,
return -ENOMEM;
err = -ENOMEM;
for (i = 0; i < nr_pages; i++) {
- pages[i] = __page_cache_alloc(GFP_NOFS);
+ pages[i] = __page_cache_alloc(GFP_NOFS, 0);
if (!pages[i]) {
nr_pages = i;
goto out;
diff --git a/fs/logfs/readwrite.c b/fs/logfs/readwrite.c
index 4153e65..b70fcfe 100644
--- a/fs/logfs/readwrite.c
+++ b/fs/logfs/readwrite.c
@@ -316,11 +316,14 @@ static struct page *logfs_get_write_page(struct inode *inode, u64 bix,
int err;

repeat:
- page = find_get_page(mapping, index);
- if (!page) {
- page = __page_cache_alloc(GFP_NOFS);
+ page = __find_get_page(mapping, index);
+ if (!page || radix_tree_exceptional_entry(page)) {
+ unsigned long distance = workingset_refault_distance(page);
+
+ page = __page_cache_alloc(GFP_NOFS, distance);
if (!page)
return NULL;
+ set_page_private(page, distance);
err = add_to_page_cache_lru(page, mapping, index, GFP_NOFS);
if (unlikely(err)) {
page_cache_release(page);
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index c587e2d..ccca902 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -412,15 +412,20 @@ static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
BUG_ON(!nr_pages);
err = nr = 0;
do {
- pages[nr] = find_lock_page(mapping, index);
- if (!pages[nr]) {
+ pages[nr] = __find_lock_page(mapping, index);
+ if (!pages[nr] || radix_tree_exceptional_entry(pages[nr])) {
+ unsigned long distance;
+
+ distance = workingset_refault_distance(pages[nr]);
if (!*cached_page) {
- *cached_page = page_cache_alloc(mapping);
+ *cached_page = page_cache_alloc(mapping,
+ distance);
if (unlikely(!*cached_page)) {
err = -ENOMEM;
goto err_out;
}
}
+ set_page_private(*cached_page, distance);
err = add_to_page_cache_lru(*cached_page, mapping, index,
GFP_KERNEL);
if (unlikely(err)) {
diff --git a/fs/splice.c b/fs/splice.c
index 1ec0493..96cbad0 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -347,15 +347,17 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
* Page could be there, find_get_pages_contig() breaks on
* the first hole.
*/
- page = find_get_page(mapping, index);
- if (!page) {
+ page = __find_get_page(mapping, index);
+ if (!page || radix_tree_exceptional_entry(page)) {
+ unsigned long distance;
/*
* page didn't exist, allocate one.
*/
- page = page_cache_alloc_cold(mapping);
+ distance = workingset_refault_distance(page);
+ page = page_cache_alloc_cold(mapping, distance);
if (!page)
break;
-
+ set_page_private(page, distance);
error = add_to_page_cache_lru(page, mapping, index,
GFP_KERNEL);
if (unlikely(error)) {
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index c1abb88..7ddfc69 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -212,28 +212,38 @@ static inline void page_unfreeze_refs(struct page *page, int count)
}

#ifdef CONFIG_NUMA
-extern struct page *__page_cache_alloc(gfp_t gfp);
+extern struct page *__page_cache_alloc(gfp_t, unsigned long);
#else
-static inline struct page *__page_cache_alloc(gfp_t gfp)
+static inline struct page *__page_cache_alloc(gfp_t gfp,
+ unsigned long refault_distance)
{
- return alloc_pages(gfp, 0);
+ struct page *page;
+
+ current->refault_distance = refault_distance;
+ page = alloc_pages(gfp, 0);
+ current->refault_distance = 0;
}
#endif

-static inline struct page *page_cache_alloc(struct address_space *x)
+static inline struct page *page_cache_alloc(struct address_space *x,
+ unsigned long refault_distance)
{
- return __page_cache_alloc(mapping_gfp_mask(x));
+ return __page_cache_alloc(mapping_gfp_mask(x), refault_distance);
}

-static inline struct page *page_cache_alloc_cold(struct address_space *x)
+static inline struct page *page_cache_alloc_cold(struct address_space *x,
+ unsigned long refault_distance)
{
- return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
+ return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD,
+ refault_distance);
}

-static inline struct page *page_cache_alloc_readahead(struct address_space *x)
+static inline struct page *page_cache_alloc_readahead(struct address_space *x,
+ unsigned long refault_distance)
{
return __page_cache_alloc(mapping_gfp_mask(x) |
- __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN);
+ __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN,
+ refault_distance);
}

typedef int filler_t(void *, struct page *);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0657368..f1a984b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1296,6 +1296,7 @@ struct task_struct {
#endif

struct mm_struct *mm, *active_mm;
+ unsigned long refault_distance;
#ifdef CONFIG_COMPAT_BRK
unsigned brk_randomized:1;
#endif
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 3e60228..03d327f 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -204,6 +204,12 @@ struct swap_list_t {
/* Swap 50% full? Release swapcache more aggressively.. */
#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)

+/* linux/mm/workingset.c */
+static inline unsigned long workingset_refault_distance(struct page *page)
+{
+ return 0;
+}
+
/* linux/mm/page_alloc.c */
extern unsigned long totalram_pages;
extern unsigned long totalreserve_pages;
diff --git a/mm/filemap.c b/mm/filemap.c
index 4ca12a3..288346a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -468,13 +468,19 @@ static int page_cache_insert(struct address_space *mapping, pgoff_t offset,
int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
pgoff_t offset, gfp_t gfp_mask)
{
+ unsigned long distance;
int error;

VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(PageSwapBacked(page));

+ distance = page_private(page);
+ set_page_private(page, 0);
+
+ current->refault_distance = distance;
error = mem_cgroup_cache_charge(page, current->mm,
gfp_mask & GFP_RECLAIM_MASK);
+ current->refault_distance = 0;
if (error)
goto out;

@@ -518,19 +524,21 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
EXPORT_SYMBOL_GPL(add_to_page_cache_lru);

#ifdef CONFIG_NUMA
-struct page *__page_cache_alloc(gfp_t gfp)
+struct page *__page_cache_alloc(gfp_t gfp, unsigned long refault_distance)
{
int n;
struct page *page;

+ current->refault_distance = refault_distance;
if (cpuset_do_page_mem_spread()) {
get_mems_allowed();
n = cpuset_mem_spread_node();
page = alloc_pages_exact_node(n, gfp, 0);
put_mems_allowed();
- return page;
- }
- return alloc_pages(gfp, 0);
+ } else
+ page = alloc_pages(gfp, 0);
+ current->refault_distance = 0;
+ return page;
}
EXPORT_SYMBOL(__page_cache_alloc);
#endif
@@ -810,11 +818,14 @@ struct page *find_or_create_page(struct address_space *mapping,
struct page *page;
int err;
repeat:
- page = find_lock_page(mapping, index);
- if (!page) {
- page = __page_cache_alloc(gfp_mask);
+ page = __find_lock_page(mapping, index);
+ if (!page || radix_tree_exceptional_entry(page)) {
+ unsigned long distance = workingset_refault_distance(page);
+
+ page = __page_cache_alloc(gfp_mask, distance);
if (!page)
return NULL;
+ set_page_private(page, distance);
/*
* We want a regular kernel memory (not highmem or DMA etc)
* allocation for the radix tree nodes, but we need to honour
@@ -1128,16 +1139,22 @@ EXPORT_SYMBOL(find_get_pages_tag);
struct page *
grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
{
- struct page *page = find_get_page(mapping, index);
+ struct page *page = __find_get_page(mapping, index);
+ unsigned long distance;

- if (page) {
+ if (page && !radix_tree_exceptional_entry(page)) {
if (trylock_page(page))
return page;
page_cache_release(page);
return NULL;
}
- page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
- if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
+ distance = workingset_refault_distance(page);
+ page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS,
+ distance);
+ if (!page)
+ return NULL;
+ set_page_private(page, distance);
+ if (add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
page_cache_release(page);
page = NULL;
}
@@ -1199,6 +1216,7 @@ static void do_generic_file_read(struct file *filp, loff_t *ppos,
offset = *ppos & ~PAGE_CACHE_MASK;

for (;;) {
+ unsigned long distance;
struct page *page;
pgoff_t end_index;
loff_t isize;
@@ -1211,8 +1229,9 @@ find_page:
page_cache_sync_readahead(mapping,
ra, filp,
index, last_index - index);
- page = find_get_page(mapping, index);
- if (unlikely(page == NULL))
+ page = __find_get_page(mapping, index);
+ if (unlikely(!page ||
+ radix_tree_exceptional_entry(page)))
goto no_cached_page;
}
if (PageReadahead(page)) {
@@ -1370,11 +1389,13 @@ no_cached_page:
* Ok, it wasn't cached, so we need to create a new
* page..
*/
- page = page_cache_alloc_cold(mapping);
+ distance = workingset_refault_distance(page);
+ page = page_cache_alloc_cold(mapping, distance);
if (!page) {
desc->error = -ENOMEM;
goto out;
}
+ set_page_private(page, distance);
error = add_to_page_cache_lru(page, mapping,
index, GFP_KERNEL);
if (error) {
@@ -1621,21 +1642,23 @@ SYSCALL_ALIAS(sys_readahead, SyS_readahead);
* page_cache_read - adds requested page to the page cache if not already there
* @file: file to read
* @offset: page index
+ * @distance: refault distance
*
* This adds the requested page to the page cache if it isn't already there,
* and schedules an I/O to read in its contents from disk.
*/
-static int page_cache_read(struct file *file, pgoff_t offset)
+static int page_cache_read(struct file *file, pgoff_t offset,
+ unsigned long distance)
{
struct address_space *mapping = file->f_mapping;
struct page *page;
int ret;

do {
- page = page_cache_alloc_cold(mapping);
+ page = page_cache_alloc_cold(mapping, distance);
if (!page)
return -ENOMEM;
-
+ set_page_private(page, distance);
ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
if (ret == 0)
ret = mapping->a_ops->readpage(file, page);
@@ -1738,6 +1761,7 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
struct file_ra_state *ra = &file->f_ra;
struct inode *inode = mapping->host;
pgoff_t offset = vmf->pgoff;
+ unsigned long distance;
struct page *page;
pgoff_t size;
int ret = 0;
@@ -1763,8 +1787,8 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
ret = VM_FAULT_MAJOR;
retry_find:
- page = find_get_page(mapping, offset);
- if (!page)
+ page = __find_get_page(mapping, offset);
+ if (!page || radix_tree_exceptional_entry(page))
goto no_cached_page;
}

@@ -1807,7 +1831,8 @@ no_cached_page:
* We're only likely to ever get here if MADV_RANDOM is in
* effect.
*/
- error = page_cache_read(file, offset);
+ distance = workingset_refault_distance(page);
+ error = page_cache_read(file, offset, distance);

/*
* The page we want has now been added to the page cache.
@@ -1901,11 +1926,14 @@ static struct page *__read_cache_page(struct address_space *mapping,
struct page *page;
int err;
repeat:
- page = find_get_page(mapping, index);
- if (!page) {
- page = __page_cache_alloc(gfp | __GFP_COLD);
+ page = __find_get_page(mapping, index);
+ if (!page || radix_tree_exceptional_entry(page)) {
+ unsigned long distance = workingset_refault_distance(page);
+
+ page = __page_cache_alloc(gfp | __GFP_COLD, distance);
if (!page)
return ERR_PTR(-ENOMEM);
+ set_page_private(page, distance);
err = add_to_page_cache_lru(page, mapping, index, gfp);
if (unlikely(err)) {
page_cache_release(page);
@@ -2432,18 +2460,20 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping,
gfp_t gfp_mask;
struct page *page;
gfp_t gfp_notmask = 0;
+ unsigned long distance;

gfp_mask = mapping_gfp_mask(mapping) | __GFP_WRITE;
if (flags & AOP_FLAG_NOFS)
gfp_notmask = __GFP_FS;
repeat:
- page = find_lock_page(mapping, index);
- if (page)
+ page = __find_lock_page(mapping, index);
+ if (page && !radix_tree_exceptional_entry(page))
goto found;
-
- page = __page_cache_alloc(gfp_mask & ~gfp_notmask);
+ distance = workingset_refault_distance(page);
+ page = __page_cache_alloc(gfp_mask & ~gfp_notmask, distance);
if (!page)
return NULL;
+ set_page_private(page, distance);
status = add_to_page_cache_lru(page, mapping, index,
GFP_KERNEL & ~gfp_notmask);
if (unlikely(status)) {
diff --git a/mm/readahead.c b/mm/readahead.c
index 43f9dd2..dc071cc 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -11,6 +11,7 @@
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/mm.h>
+#include <linux/swap.h>
#include <linux/export.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
@@ -170,6 +171,7 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
*/
for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
pgoff_t page_offset = offset + page_idx;
+ unsigned long distance;

if (page_offset > end_index)
break;
@@ -179,10 +181,11 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
rcu_read_unlock();
if (page && !radix_tree_exceptional_entry(page))
continue;
-
- page = page_cache_alloc_readahead(mapping);
+ distance = workingset_refault_distance(page);
+ page = page_cache_alloc_readahead(mapping, distance);
if (!page)
break;
+ set_page_private(page, distance);
page->index = page_offset;
list_add(&page->lru, &page_pool);
if (page_idx == nr_to_read - lookahead_size)
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index ad5b708..b57933a 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2218,7 +2218,7 @@ struct ceph_messenger *ceph_messenger_create(struct ceph_entity_addr *myaddr,

/* the zero page is needed if a request is "canceled" while the message
* is being written over the socket */
- msgr->zero_page = __page_cache_alloc(GFP_KERNEL | __GFP_ZERO);
+ msgr->zero_page = __page_cache_alloc(GFP_KERNEL | __GFP_ZERO, 0);
if (!msgr->zero_page) {
kfree(msgr);
return ERR_PTR(-ENOMEM);
diff --git a/net/ceph/pagelist.c b/net/ceph/pagelist.c
index 13cb409..ffc6289 100644
--- a/net/ceph/pagelist.c
+++ b/net/ceph/pagelist.c
@@ -33,7 +33,7 @@ static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
struct page *page;

if (!pl->num_pages_free) {
- page = __page_cache_alloc(GFP_NOFS);
+ page = __page_cache_alloc(GFP_NOFS, 0);
} else {
page = list_first_entry(&pl->free_list, struct page, lru);
list_del(&page->lru);
@@ -85,7 +85,7 @@ int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */

while (space > pl->num_pages_free) {
- struct page *page = __page_cache_alloc(GFP_NOFS);
+ struct page *page = __page_cache_alloc(GFP_NOFS, 0);
if (!page)
return -ENOMEM;
list_add_tail(&page->lru, &pl->free_list);
diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c
index cd9c21d..4bc4ffd 100644
--- a/net/ceph/pagevec.c
+++ b/net/ceph/pagevec.c
@@ -79,7 +79,7 @@ struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags)
if (!pages)
return ERR_PTR(-ENOMEM);
for (i = 0; i < num_pages; i++) {
- pages[i] = __page_cache_alloc(flags);
+ pages[i] = __page_cache_alloc(flags, 0);
if (pages[i] == NULL) {
ceph_release_page_vector(pages, i);
return ERR_PTR(-ENOMEM);
--
1.7.7.6

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