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mm: compaction: introduce sync-light migration for use by compaction

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This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT
mode that avoids writing back pages to backing storage.  Async compaction
maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT.
For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is
used.

This avoids sync compaction stalling for an excessive length of time,
particularly when copying files to a USB stick where there might be a
large number of dirty pages backed by a filesystem that does not support
->writepages.

[aarcange@redhat.com: This patch is heavily based on Andrea's work]
[akpm@linux-foundation.org: fix fs/nfs/write.c build]
[akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2012-01-12 17:19:43 -08:00 committed by Linus Torvalds
parent 66199712e9
commit a6bc32b899
11 changed files with 76 additions and 52 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
fs/btrfs/disk-io.c
View file

@ -872,7 +872,8 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
#ifdef CONFIG_MIGRATION #ifdef CONFIG_MIGRATION
static int btree_migratepage(struct address_space *mapping, static int btree_migratepage(struct address_space *mapping,
struct page *newpage, struct page *page, bool sync) struct page *newpage, struct page *page,
enum migrate_mode mode)
{ {
/* /*
* we can't safely write a btree page from here, * we can't safely write a btree page from here,
@ -887,7 +888,7 @@ static int btree_migratepage(struct address_space *mapping,
if (page_has_private(page) && if (page_has_private(page) &&
!try_to_release_page(page, GFP_KERNEL)) !try_to_release_page(page, GFP_KERNEL))
return -EAGAIN; return -EAGAIN;
return migrate_page(mapping, newpage, page, sync); return migrate_page(mapping, newpage, page, mode);
} }
#endif #endif

2
fs/hugetlbfs/inode.c
View file

@ -584,7 +584,7 @@ static int hugetlbfs_set_page_dirty(struct page *page)
static int hugetlbfs_migrate_page(struct address_space *mapping, static int hugetlbfs_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page, struct page *newpage, struct page *page,
bool sync) enum migrate_mode mode)
{ {
int rc; int rc;

2
fs/nfs/internal.h
View file

@ -332,7 +332,7 @@ void nfs_commit_release_pages(struct nfs_write_data *data);
#ifdef CONFIG_MIGRATION #ifdef CONFIG_MIGRATION
extern int nfs_migrate_page(struct address_space *, extern int nfs_migrate_page(struct address_space *,
struct page *, struct page *, bool); struct page *, struct page *, enum migrate_mode);
#else #else
#define nfs_migrate_page NULL #define nfs_migrate_page NULL
#endif #endif

4
fs/nfs/write.c
View file

@ -1688,7 +1688,7 @@ int nfs_wb_page(struct inode *inode, struct page *page)
#ifdef CONFIG_MIGRATION #ifdef CONFIG_MIGRATION
int nfs_migrate_page(struct address_space *mapping, struct page *newpage, int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
struct page *page, bool sync) struct page *page, enum migrate_mode mode)
{ {
/* /*
* If PagePrivate is set, then the page is currently associated with * If PagePrivate is set, then the page is currently associated with
@ -1703,7 +1703,7 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
nfs_fscache_release_page(page, GFP_KERNEL); nfs_fscache_release_page(page, GFP_KERNEL);
return migrate_page(mapping, newpage, page, sync); return migrate_page(mapping, newpage, page, mode);
} }
#endif #endif

6
include/linux/fs.h
View file

@ -525,6 +525,7 @@ enum positive_aop_returns {
struct page; struct page;
struct address_space; struct address_space;
struct writeback_control; struct writeback_control;
enum migrate_mode;
struct iov_iter { struct iov_iter {
const struct iovec *iov; const struct iovec *iov;
@ -614,7 +615,7 @@ struct address_space_operations {
* is false, it must not block. * is false, it must not block.
*/ */
int (*migratepage) (struct address_space *, int (*migratepage) (struct address_space *,
struct page *, struct page *, bool); struct page *, struct page *, enum migrate_mode);
int (*launder_page) (struct page *); int (*launder_page) (struct page *);
int (*is_partially_uptodate) (struct page *, read_descriptor_t *, int (*is_partially_uptodate) (struct page *, read_descriptor_t *,
unsigned long); unsigned long);
@ -2540,7 +2541,8 @@ extern int generic_check_addressable(unsigned, u64);
#ifdef CONFIG_MIGRATION #ifdef CONFIG_MIGRATION
extern int buffer_migrate_page(struct address_space *, extern int buffer_migrate_page(struct address_space *,
struct page *, struct page *, bool); struct page *, struct page *,
enum migrate_mode);
#else #else
#define buffer_migrate_page NULL #define buffer_migrate_page NULL
#endif #endif

23
include/linux/migrate.h
View file

@ -6,18 +6,31 @@
typedef struct page *new_page_t(struct page *, unsigned long private, int **); typedef struct page *new_page_t(struct page *, unsigned long private, int **);
/*
* MIGRATE_ASYNC means never block
* MIGRATE_SYNC_LIGHT in the current implementation means to allow blocking
* on most operations but not ->writepage as the potential stall time
* is too significant
* MIGRATE_SYNC will block when migrating pages
*/
enum migrate_mode {
MIGRATE_ASYNC,
MIGRATE_SYNC_LIGHT,
MIGRATE_SYNC,
};
#ifdef CONFIG_MIGRATION #ifdef CONFIG_MIGRATION
#define PAGE_MIGRATION 1 #define PAGE_MIGRATION 1
extern void putback_lru_pages(struct list_head *l); extern void putback_lru_pages(struct list_head *l);
extern int migrate_page(struct address_space *, extern int migrate_page(struct address_space *,
struct page *, struct page *, bool); struct page *, struct page *, enum migrate_mode);
extern int migrate_pages(struct list_head *l, new_page_t x, extern int migrate_pages(struct list_head *l, new_page_t x,
unsigned long private, bool offlining, unsigned long private, bool offlining,
bool sync); enum migrate_mode mode);
extern int migrate_huge_pages(struct list_head *l, new_page_t x, extern int migrate_huge_pages(struct list_head *l, new_page_t x,
unsigned long private, bool offlining, unsigned long private, bool offlining,
bool sync); enum migrate_mode mode);
extern int fail_migrate_page(struct address_space *, extern int fail_migrate_page(struct address_space *,
struct page *, struct page *); struct page *, struct page *);
@ -36,10 +49,10 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
static inline void putback_lru_pages(struct list_head *l) {} static inline void putback_lru_pages(struct list_head *l) {}
static inline int migrate_pages(struct list_head *l, new_page_t x, static inline int migrate_pages(struct list_head *l, new_page_t x,
unsigned long private, bool offlining, unsigned long private, bool offlining,
bool sync) { return -ENOSYS; } enum migrate_mode mode) { return -ENOSYS; }
static inline int migrate_huge_pages(struct list_head *l, new_page_t x, static inline int migrate_huge_pages(struct list_head *l, new_page_t x,
unsigned long private, bool offlining, unsigned long private, bool offlining,
bool sync) { return -ENOSYS; } enum migrate_mode mode) { return -ENOSYS; }
static inline int migrate_prep(void) { return -ENOSYS; } static inline int migrate_prep(void) { return -ENOSYS; }
static inline int migrate_prep_local(void) { return -ENOSYS; } static inline int migrate_prep_local(void) { return -ENOSYS; }

2
mm/compaction.c
View file

@ -557,7 +557,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
nr_migrate = cc->nr_migratepages; nr_migrate = cc->nr_migratepages;
err = migrate_pages(&cc->migratepages, compaction_alloc, err = migrate_pages(&cc->migratepages, compaction_alloc,
(unsigned long)cc, false, (unsigned long)cc, false,
cc->sync); cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC);
update_nr_listpages(cc); update_nr_listpages(cc);
nr_remaining = cc->nr_migratepages; nr_remaining = cc->nr_migratepages;

2
mm/memory-failure.c
View file

@ -1557,7 +1557,7 @@ int soft_offline_page(struct page *page, int flags)
page_is_file_cache(page)); page_is_file_cache(page));
list_add(&page->lru, &pagelist); list_add(&page->lru, &pagelist);
ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
0, true); 0, MIGRATE_SYNC);
if (ret) { if (ret) {
putback_lru_pages(&pagelist); putback_lru_pages(&pagelist);
pr_info("soft offline: %#lx: migration failed %d, type %lx\n", pr_info("soft offline: %#lx: migration failed %d, type %lx\n",

2
mm/memory_hotplug.c
View file

@ -809,7 +809,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
} }
/* this function returns # of failed pages */ /* this function returns # of failed pages */
ret = migrate_pages(&source, hotremove_migrate_alloc, 0, ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
true, true); true, MIGRATE_SYNC);
if (ret) if (ret)
putback_lru_pages(&source); putback_lru_pages(&source);
} }

2
mm/mempolicy.c
View file

@ -942,7 +942,7 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
if (!list_empty(&pagelist)) { if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_node_page, dest, err = migrate_pages(&pagelist, new_node_page, dest,
false, true); false, MIGRATE_SYNC);
if (err) if (err)
putback_lru_pages(&pagelist); putback_lru_pages(&pagelist);
} }

78
mm/migrate.c
View file

@ -218,12 +218,13 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
#ifdef CONFIG_BLOCK #ifdef CONFIG_BLOCK
/* Returns true if all buffers are successfully locked */ /* Returns true if all buffers are successfully locked */
static bool buffer_migrate_lock_buffers(struct buffer_head *head, bool sync) static bool buffer_migrate_lock_buffers(struct buffer_head *head,
enum migrate_mode mode)
{ {
struct buffer_head *bh = head; struct buffer_head *bh = head;
/* Simple case, sync compaction */ /* Simple case, sync compaction */
if (sync) { if (mode != MIGRATE_ASYNC) {
do { do {
get_bh(bh); get_bh(bh);
lock_buffer(bh); lock_buffer(bh);
@ -259,7 +260,7 @@ static bool buffer_migrate_lock_buffers(struct buffer_head *head, bool sync)
} }
#else #else
static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
bool sync) enum migrate_mode mode)
{ {
return true; return true;
} }
@ -275,7 +276,7 @@ static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
*/ */
static int migrate_page_move_mapping(struct address_space *mapping, static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page, struct page *newpage, struct page *page,
struct buffer_head *head, bool sync) struct buffer_head *head, enum migrate_mode mode)
{ {
int expected_count; int expected_count;
void **pslot; void **pslot;
@ -311,7 +312,8 @@ static int migrate_page_move_mapping(struct address_space *mapping,
* the mapping back due to an elevated page count, we would have to * the mapping back due to an elevated page count, we would have to
* block waiting on other references to be dropped. * block waiting on other references to be dropped.
*/ */
if (!sync && head && !buffer_migrate_lock_buffers(head, sync)) { if (mode == MIGRATE_ASYNC && head &&
!buffer_migrate_lock_buffers(head, mode)) {
page_unfreeze_refs(page, expected_count); page_unfreeze_refs(page, expected_count);
spin_unlock_irq(&mapping->tree_lock); spin_unlock_irq(&mapping->tree_lock);
return -EAGAIN; return -EAGAIN;
@ -472,13 +474,14 @@ EXPORT_SYMBOL(fail_migrate_page);
* Pages are locked upon entry and exit. * Pages are locked upon entry and exit.
*/ */
int migrate_page(struct address_space *mapping, int migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page, bool sync) struct page *newpage, struct page *page,
enum migrate_mode mode)
{ {
int rc; int rc;
BUG_ON(PageWriteback(page)); /* Writeback must be complete */ BUG_ON(PageWriteback(page)); /* Writeback must be complete */
rc = migrate_page_move_mapping(mapping, newpage, page, NULL, sync); rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode);
if (rc) if (rc)
return rc; return rc;
@ -495,17 +498,17 @@ EXPORT_SYMBOL(migrate_page);
* exist. * exist.
*/ */
int buffer_migrate_page(struct address_space *mapping, int buffer_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page, bool sync) struct page *newpage, struct page *page, enum migrate_mode mode)
{ {
struct buffer_head *bh, *head; struct buffer_head *bh, *head;
int rc; int rc;
if (!page_has_buffers(page)) if (!page_has_buffers(page))
return migrate_page(mapping, newpage, page, sync); return migrate_page(mapping, newpage, page, mode);
head = page_buffers(page); head = page_buffers(page);
rc = migrate_page_move_mapping(mapping, newpage, page, head, sync); rc = migrate_page_move_mapping(mapping, newpage, page, head, mode);
if (rc) if (rc)
return rc; return rc;
@ -515,8 +518,8 @@ int buffer_migrate_page(struct address_space *mapping,
* with an IRQ-safe spinlock held. In the sync case, the buffers * with an IRQ-safe spinlock held. In the sync case, the buffers
* need to be locked now * need to be locked now
*/ */
if (sync) if (mode != MIGRATE_ASYNC)
BUG_ON(!buffer_migrate_lock_buffers(head, sync)); BUG_ON(!buffer_migrate_lock_buffers(head, mode));
ClearPagePrivate(page); ClearPagePrivate(page);
set_page_private(newpage, page_private(page)); set_page_private(newpage, page_private(page));
@ -593,10 +596,11 @@ static int writeout(struct address_space *mapping, struct page *page)
* Default handling if a filesystem does not provide a migration function. * Default handling if a filesystem does not provide a migration function.
*/ */
static int fallback_migrate_page(struct address_space *mapping, static int fallback_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page, bool sync) struct page *newpage, struct page *page, enum migrate_mode mode)
{ {
if (PageDirty(page)) { if (PageDirty(page)) {
if (!sync) /* Only writeback pages in full synchronous migration */
if (mode != MIGRATE_SYNC)
return -EBUSY; return -EBUSY;
return writeout(mapping, page); return writeout(mapping, page);
} }
@ -609,7 +613,7 @@ static int fallback_migrate_page(struct address_space *mapping,
!try_to_release_page(page, GFP_KERNEL)) !try_to_release_page(page, GFP_KERNEL))
return -EAGAIN; return -EAGAIN;
return migrate_page(mapping, newpage, page, sync); return migrate_page(mapping, newpage, page, mode);
} }
/* /*
@ -624,7 +628,7 @@ static int fallback_migrate_page(struct address_space *mapping,
* == 0 - success * == 0 - success
*/ */
static int move_to_new_page(struct page *newpage, struct page *page, static int move_to_new_page(struct page *newpage, struct page *page,
int remap_swapcache, bool sync) int remap_swapcache, enum migrate_mode mode)
{ {
struct address_space *mapping; struct address_space *mapping;
int rc; int rc;
@ -645,7 +649,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
mapping = page_mapping(page); mapping = page_mapping(page);
if (!mapping) if (!mapping)
rc = migrate_page(mapping, newpage, page, sync); rc = migrate_page(mapping, newpage, page, mode);
else if (mapping->a_ops->migratepage) else if (mapping->a_ops->migratepage)
/* /*
* Most pages have a mapping and most filesystems provide a * Most pages have a mapping and most filesystems provide a
@ -654,9 +658,9 @@ static int move_to_new_page(struct page *newpage, struct page *page,
* is the most common path for page migration. * is the most common path for page migration.
*/ */
rc = mapping->a_ops->migratepage(mapping, rc = mapping->a_ops->migratepage(mapping,
newpage, page, sync); newpage, page, mode);
else else
rc = fallback_migrate_page(mapping, newpage, page, sync); rc = fallback_migrate_page(mapping, newpage, page, mode);
if (rc) { if (rc) {
newpage->mapping = NULL; newpage->mapping = NULL;
@ -671,7 +675,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
} }
static int __unmap_and_move(struct page *page, struct page *newpage, static int __unmap_and_move(struct page *page, struct page *newpage,
int force, bool offlining, bool sync) int force, bool offlining, enum migrate_mode mode)
{ {
int rc = -EAGAIN; int rc = -EAGAIN;
int remap_swapcache = 1; int remap_swapcache = 1;
@ -680,7 +684,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
struct anon_vma *anon_vma = NULL; struct anon_vma *anon_vma = NULL;
if (!trylock_page(page)) { if (!trylock_page(page)) {
if (!force || !sync) if (!force || mode == MIGRATE_ASYNC)
goto out; goto out;
/* /*
@ -726,10 +730,12 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
if (PageWriteback(page)) { if (PageWriteback(page)) {
/* /*
* For !sync, there is no point retrying as the retry loop * Only in the case of a full syncronous migration is it
* is expected to be too short for PageWriteback to be cleared * necessary to wait for PageWriteback. In the async case,
* the retry loop is too short and in the sync-light case,
* the overhead of stalling is too much
*/ */
if (!sync) { if (mode != MIGRATE_SYNC) {
rc = -EBUSY; rc = -EBUSY;
goto uncharge; goto uncharge;
} }
@ -800,7 +806,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
skip_unmap: skip_unmap:
if (!page_mapped(page)) if (!page_mapped(page))
rc = move_to_new_page(newpage, page, remap_swapcache, sync); rc = move_to_new_page(newpage, page, remap_swapcache, mode);
if (rc && remap_swapcache) if (rc && remap_swapcache)
remove_migration_ptes(page, page); remove_migration_ptes(page, page);
@ -823,7 +829,8 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
* to the newly allocated page in newpage. * to the newly allocated page in newpage.
*/ */
static int unmap_and_move(new_page_t get_new_page, unsigned long private, static int unmap_and_move(new_page_t get_new_page, unsigned long private,
struct page *page, int force, bool offlining, bool sync) struct page *page, int force, bool offlining,
enum migrate_mode mode)
{ {
int rc = 0; int rc = 0;
int *result = NULL; int *result = NULL;
@ -843,7 +850,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
if (unlikely(split_huge_page(page))) if (unlikely(split_huge_page(page)))
goto out; goto out;
rc = __unmap_and_move(page, newpage, force, offlining, sync); rc = __unmap_and_move(page, newpage, force, offlining, mode);
out: out:
if (rc != -EAGAIN) { if (rc != -EAGAIN) {
/* /*
@ -891,7 +898,8 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
*/ */
static int unmap_and_move_huge_page(new_page_t get_new_page, static int unmap_and_move_huge_page(new_page_t get_new_page,
unsigned long private, struct page *hpage, unsigned long private, struct page *hpage,
int force, bool offlining, bool sync) int force, bool offlining,
enum migrate_mode mode)
{ {
int rc = 0; int rc = 0;
int *result = NULL; int *result = NULL;
@ -904,7 +912,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
rc = -EAGAIN; rc = -EAGAIN;
if (!trylock_page(hpage)) { if (!trylock_page(hpage)) {
if (!force || !sync) if (!force || mode != MIGRATE_SYNC)
goto out; goto out;
lock_page(hpage); lock_page(hpage);
} }
@ -915,7 +923,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
if (!page_mapped(hpage)) if (!page_mapped(hpage))
rc = move_to_new_page(new_hpage, hpage, 1, sync); rc = move_to_new_page(new_hpage, hpage, 1, mode);
if (rc) if (rc)
remove_migration_ptes(hpage, hpage); remove_migration_ptes(hpage, hpage);
@ -958,7 +966,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
*/ */
int migrate_pages(struct list_head *from, int migrate_pages(struct list_head *from,
new_page_t get_new_page, unsigned long private, bool offlining, new_page_t get_new_page, unsigned long private, bool offlining,
bool sync) enum migrate_mode mode)
{ {
int retry = 1; int retry = 1;
int nr_failed = 0; int nr_failed = 0;
@ -979,7 +987,7 @@ int migrate_pages(struct list_head *from,
rc = unmap_and_move(get_new_page, private, rc = unmap_and_move(get_new_page, private,
page, pass > 2, offlining, page, pass > 2, offlining,
sync); mode);
switch(rc) { switch(rc) {
case -ENOMEM: case -ENOMEM:
@ -1009,7 +1017,7 @@ int migrate_pages(struct list_head *from,
int migrate_huge_pages(struct list_head *from, int migrate_huge_pages(struct list_head *from,
new_page_t get_new_page, unsigned long private, bool offlining, new_page_t get_new_page, unsigned long private, bool offlining,
bool sync) enum migrate_mode mode)
{ {
int retry = 1; int retry = 1;
int nr_failed = 0; int nr_failed = 0;
@ -1026,7 +1034,7 @@ int migrate_huge_pages(struct list_head *from,
rc = unmap_and_move_huge_page(get_new_page, rc = unmap_and_move_huge_page(get_new_page,
private, page, pass > 2, offlining, private, page, pass > 2, offlining,
sync); mode);
switch(rc) { switch(rc) {
case -ENOMEM: case -ENOMEM:
@ -1155,7 +1163,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
err = 0; err = 0;
if (!list_empty(&pagelist)) { if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_page_node, err = migrate_pages(&pagelist, new_page_node,
(unsigned long)pm, 0, true); (unsigned long)pm, 0, MIGRATE_SYNC);
if (err) if (err)
putback_lru_pages(&pagelist); putback_lru_pages(&pagelist);
} }