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Date: Tue, 26 Jan 2016 16:00:02 -0500
From: Johannes Weiner <hannes@...xchg.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Vladimir Davydov <vdavydov@...tuozzo.com>,
Michal Hocko <mhocko@...e.cz>, linux-mm@...ck.org,
cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-team@...com
Subject: [PATCH 1/5] mm: memcontrol: generalize locking for the page->mem_cgroup binding
So far the only sites that needed to exclude charge migration to
stabilize page->mem_cgroup have been per-cgroup page statistics, hence
the name mem_cgroup_begin_page_stat(). But per-cgroup thrash detection
will add another site that needs to ensure page->mem_cgroup lifetime.
Rename these locking functions to the more generic lock_page_memcg()
and unlock_page_memcg(). Since charge migration is a cgroup1 feature
only, we might be able to delete it at some point, and these now easy
to identify locking sites along with it.
Suggested-by: Vladimir Davydov <vdavydov@...tuozzo.com>
Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
fs/buffer.c | 14 +++++++-------
fs/xfs/xfs_aops.c | 8 ++++----
include/linux/memcontrol.h | 16 +++++++++++-----
mm/filemap.c | 12 ++++++------
mm/memcontrol.c | 34 ++++++++++++++--------------------
mm/page-writeback.c | 28 ++++++++++++++--------------
mm/rmap.c | 8 ++++----
mm/truncate.c | 6 +++---
mm/vmscan.c | 8 ++++----
9 files changed, 67 insertions(+), 67 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index e1632abb4ca9..dc991510bb06 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -621,7 +621,7 @@ EXPORT_SYMBOL(mark_buffer_dirty_inode);
* If warn is true, then emit a warning if the page is not uptodate and has
* not been truncated.
*
- * The caller must hold mem_cgroup_begin_page_stat() lock.
+ * The caller must hold lock_page_memcg().
*/
static void __set_page_dirty(struct page *page, struct address_space *mapping,
struct mem_cgroup *memcg, int warn)
@@ -683,17 +683,17 @@ int __set_page_dirty_buffers(struct page *page)
} while (bh != head);
}
/*
- * Use mem_group_begin_page_stat() to keep PageDirty synchronized with
- * per-memcg dirty page counters.
+ * Lock out page->mem_cgroup migration to keep PageDirty
+ * synchronized with per-memcg dirty page counters.
*/
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
newly_dirty = !TestSetPageDirty(page);
spin_unlock(&mapping->private_lock);
if (newly_dirty)
__set_page_dirty(page, mapping, memcg, 1);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (newly_dirty)
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
@@ -1169,13 +1169,13 @@ void mark_buffer_dirty(struct buffer_head *bh)
struct address_space *mapping = NULL;
struct mem_cgroup *memcg;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
if (!TestSetPageDirty(page)) {
mapping = page_mapping(page);
if (mapping)
__set_page_dirty(page, mapping, memcg, 0);
}
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (mapping)
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
}
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 379c089fb051..28eb6f535ca9 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1974,10 +1974,10 @@ xfs_vm_set_page_dirty(
} while (bh != head);
}
/*
- * Use mem_group_begin_page_stat() to keep PageDirty synchronized with
- * per-memcg dirty page counters.
+ * Lock out page->mem_cgroup migration to keep PageDirty
+ * synchronized with per-memcg dirty page counters.
*/
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
newly_dirty = !TestSetPageDirty(page);
spin_unlock(&mapping->private_lock);
@@ -1994,7 +1994,7 @@ xfs_vm_set_page_dirty(
}
spin_unlock_irqrestore(&mapping->tree_lock, flags);
}
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (newly_dirty)
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
return newly_dirty;
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 792c8981e633..2685aaf91511 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -429,8 +429,8 @@ bool mem_cgroup_oom_synchronize(bool wait);
extern int do_swap_account;
#endif
-struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page);
-void mem_cgroup_end_page_stat(struct mem_cgroup *memcg);
+struct mem_cgroup *lock_page_memcg(struct page *page);
+void unlock_page_memcg(struct mem_cgroup *memcg);
/**
* mem_cgroup_update_page_stat - update page state statistics
@@ -438,7 +438,13 @@ void mem_cgroup_end_page_stat(struct mem_cgroup *memcg);
* @idx: page state item to account
* @val: number of pages (positive or negative)
*
- * See mem_cgroup_begin_page_stat() for locking requirements.
+ * Callers must use lock_page_memcg() to prevent double accounting
+ * when the page is concurrently being moved to another memcg:
+ *
+ * memcg = lock_page_memcg(page);
+ * if (TestClearPageState(page))
+ * mem_cgroup_update_page_stat(memcg, state, -1);
+ * unlock_page_memcg(memcg);
*/
static inline void mem_cgroup_update_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx, int val)
@@ -613,12 +619,12 @@ mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
{
}
-static inline struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page)
+static inline struct mem_cgroup *lock_page_memcg(struct page *page)
{
return NULL;
}
-static inline void mem_cgroup_end_page_stat(struct mem_cgroup *memcg)
+static inline void unlock_page_memcg(struct mem_cgroup *memcg)
{
}
diff --git a/mm/filemap.c b/mm/filemap.c
index 0720c9d19365..f812976350ca 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -101,7 +101,7 @@
* ->tree_lock (page_remove_rmap->set_page_dirty)
* bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
* ->inode->i_lock (page_remove_rmap->set_page_dirty)
- * ->memcg->move_lock (page_remove_rmap->mem_cgroup_begin_page_stat)
+ * ->memcg->move_lock (page_remove_rmap->lock_page_memcg)
* bdi.wb->list_lock (zap_pte_range->set_page_dirty)
* ->inode->i_lock (zap_pte_range->set_page_dirty)
* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
@@ -177,7 +177,7 @@ static void page_cache_tree_delete(struct address_space *mapping,
* Delete a page from the page cache and free it. Caller has to make
* sure the page is locked and that nobody else uses it - or that usage
* is safe. The caller must hold the mapping's tree_lock and
- * mem_cgroup_begin_page_stat().
+ * lock_page_memcg().
*/
void __delete_from_page_cache(struct page *page, void *shadow,
struct mem_cgroup *memcg)
@@ -240,11 +240,11 @@ void delete_from_page_cache(struct page *page)
freepage = mapping->a_ops->freepage;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
spin_lock_irqsave(&mapping->tree_lock, flags);
__delete_from_page_cache(page, NULL, memcg);
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (freepage)
freepage(page);
@@ -542,7 +542,7 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
new->mapping = mapping;
new->index = offset;
- memcg = mem_cgroup_begin_page_stat(old);
+ memcg = lock_page_memcg(old);
spin_lock_irqsave(&mapping->tree_lock, flags);
__delete_from_page_cache(old, NULL, memcg);
error = radix_tree_insert(&mapping->page_tree, offset, new);
@@ -557,7 +557,7 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
if (PageSwapBacked(new))
__inc_zone_page_state(new, NR_SHMEM);
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
mem_cgroup_replace_page(old, new);
radix_tree_preload_end();
if (freepage)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d06cae2de783..953f0f984392 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1709,19 +1709,13 @@ cleanup:
}
/**
- * mem_cgroup_begin_page_stat - begin a page state statistics transaction
- * @page: page that is going to change accounted state
- *
- * This function must mark the beginning of an accounted page state
- * change to prevent double accounting when the page is concurrently
- * being moved to another memcg:
+ * lock_page_memcg - lock a page->mem_cgroup binding
+ * @page: the page
*
- * memcg = mem_cgroup_begin_page_stat(page);
- * if (TestClearPageState(page))
- * mem_cgroup_update_page_stat(memcg, state, -1);
- * mem_cgroup_end_page_stat(memcg);
+ * This function protects unlocked LRU pages from being moved to
+ * another cgroup and stabilizes their page->mem_cgroup binding.
*/
-struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page)
+struct mem_cgroup *lock_page_memcg(struct page *page)
{
struct mem_cgroup *memcg;
unsigned long flags;
@@ -1759,20 +1753,20 @@ again:
/*
* When charge migration first begins, we can have locked and
* unlocked page stat updates happening concurrently. Track
- * the task who has the lock for mem_cgroup_end_page_stat().
+ * the task who has the lock for unlock_page_memcg().
*/
memcg->move_lock_task = current;
memcg->move_lock_flags = flags;
return memcg;
}
-EXPORT_SYMBOL(mem_cgroup_begin_page_stat);
+EXPORT_SYMBOL(lock_page_memcg);
/**
- * mem_cgroup_end_page_stat - finish a page state statistics transaction
- * @memcg: the memcg that was accounted against
+ * unlock_page_memcg - unlock a page->mem_cgroup binding
+ * @memcg: the memcg returned by lock_page_memcg()
*/
-void mem_cgroup_end_page_stat(struct mem_cgroup *memcg)
+void unlock_page_memcg(struct mem_cgroup *memcg)
{
if (memcg && memcg->move_lock_task == current) {
unsigned long flags = memcg->move_lock_flags;
@@ -1785,7 +1779,7 @@ void mem_cgroup_end_page_stat(struct mem_cgroup *memcg)
rcu_read_unlock();
}
-EXPORT_SYMBOL(mem_cgroup_end_page_stat);
+EXPORT_SYMBOL(unlock_page_memcg);
/*
* size of first charge trial. "32" comes from vmscan.c's magic value.
@@ -4923,9 +4917,9 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
lru_add_drain_all();
/*
- * Signal mem_cgroup_begin_page_stat() to take the memcg's
- * move_lock while we're moving its pages to another memcg.
- * Then wait for already started RCU-only updates to finish.
+ * Signal lock_page_memcg() to take the memcg's move_lock
+ * while we're moving its pages to another memcg. Then wait
+ * for already started RCU-only updates to finish.
*/
atomic_inc(&mc.from->moving_account);
synchronize_rcu();
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index d782cbab735a..2b5ea1271e32 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2410,7 +2410,7 @@ int __set_page_dirty_no_writeback(struct page *page)
/*
* Helper function for set_page_dirty family.
*
- * Caller must hold mem_cgroup_begin_page_stat().
+ * Caller must hold lock_page_memcg().
*
* NOTE: This relies on being atomic wrt interrupts.
*/
@@ -2442,7 +2442,7 @@ EXPORT_SYMBOL(account_page_dirtied);
/*
* Helper function for deaccounting dirty page without writeback.
*
- * Caller must hold mem_cgroup_begin_page_stat().
+ * Caller must hold lock_page_memcg().
*/
void account_page_cleaned(struct page *page, struct address_space *mapping,
struct mem_cgroup *memcg, struct bdi_writeback *wb)
@@ -2471,13 +2471,13 @@ int __set_page_dirty_nobuffers(struct page *page)
{
struct mem_cgroup *memcg;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
if (!TestSetPageDirty(page)) {
struct address_space *mapping = page_mapping(page);
unsigned long flags;
if (!mapping) {
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return 1;
}
@@ -2488,7 +2488,7 @@ int __set_page_dirty_nobuffers(struct page *page)
radix_tree_tag_set(&mapping->page_tree, page_index(page),
PAGECACHE_TAG_DIRTY);
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (mapping->host) {
/* !PageAnon && !swapper_space */
@@ -2496,7 +2496,7 @@ int __set_page_dirty_nobuffers(struct page *page)
}
return 1;
}
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return 0;
}
EXPORT_SYMBOL(__set_page_dirty_nobuffers);
@@ -2629,14 +2629,14 @@ void cancel_dirty_page(struct page *page)
struct mem_cgroup *memcg;
bool locked;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
wb = unlocked_inode_to_wb_begin(inode, &locked);
if (TestClearPageDirty(page))
account_page_cleaned(page, mapping, memcg, wb);
unlocked_inode_to_wb_end(inode, locked);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
} else {
ClearPageDirty(page);
}
@@ -2705,7 +2705,7 @@ int clear_page_dirty_for_io(struct page *page)
* always locked coming in here, so we get the desired
* exclusion.
*/
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
wb = unlocked_inode_to_wb_begin(inode, &locked);
if (TestClearPageDirty(page)) {
mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
@@ -2714,7 +2714,7 @@ int clear_page_dirty_for_io(struct page *page)
ret = 1;
}
unlocked_inode_to_wb_end(inode, locked);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return ret;
}
return TestClearPageDirty(page);
@@ -2727,7 +2727,7 @@ int test_clear_page_writeback(struct page *page)
struct mem_cgroup *memcg;
int ret;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
if (mapping) {
struct inode *inode = mapping->host;
struct backing_dev_info *bdi = inode_to_bdi(inode);
@@ -2755,7 +2755,7 @@ int test_clear_page_writeback(struct page *page)
dec_zone_page_state(page, NR_WRITEBACK);
inc_zone_page_state(page, NR_WRITTEN);
}
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return ret;
}
@@ -2765,7 +2765,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
struct mem_cgroup *memcg;
int ret;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
if (mapping) {
struct inode *inode = mapping->host;
struct backing_dev_info *bdi = inode_to_bdi(inode);
@@ -2796,7 +2796,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_WRITEBACK);
inc_zone_page_state(page, NR_WRITEBACK);
}
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return ret;
}
diff --git a/mm/rmap.c b/mm/rmap.c
index 79f3bf047f38..2871e7d3cced 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1289,19 +1289,19 @@ void page_add_file_rmap(struct page *page)
{
struct mem_cgroup *memcg;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
if (atomic_inc_and_test(&page->_mapcount)) {
__inc_zone_page_state(page, NR_FILE_MAPPED);
mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
}
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
}
static void page_remove_file_rmap(struct page *page)
{
struct mem_cgroup *memcg;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
/* Hugepages are not counted in NR_FILE_MAPPED for now. */
if (unlikely(PageHuge(page))) {
@@ -1325,7 +1325,7 @@ static void page_remove_file_rmap(struct page *page)
if (unlikely(PageMlocked(page)))
clear_page_mlock(page);
out:
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
}
static void page_remove_anon_compound_rmap(struct page *page)
diff --git a/mm/truncate.c b/mm/truncate.c
index e3ee0e27cd17..51a24f6a555d 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -528,7 +528,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
return 0;
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
spin_lock_irqsave(&mapping->tree_lock, flags);
if (PageDirty(page))
goto failed;
@@ -536,7 +536,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
BUG_ON(page_has_private(page));
__delete_from_page_cache(page, NULL, memcg);
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (mapping->a_ops->freepage)
mapping->a_ops->freepage(page);
@@ -545,7 +545,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
return 1;
failed:
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return 0;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 30e0cd7a0ceb..45771323e863 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -616,7 +616,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
BUG_ON(!PageLocked(page));
BUG_ON(mapping != page_mapping(page));
- memcg = mem_cgroup_begin_page_stat(page);
+ memcg = lock_page_memcg(page);
spin_lock_irqsave(&mapping->tree_lock, flags);
/*
* The non racy check for a busy page.
@@ -656,7 +656,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
mem_cgroup_swapout(page, swap);
__delete_from_swap_cache(page);
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
swapcache_free(swap);
} else {
void (*freepage)(struct page *);
@@ -684,7 +684,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
shadow = workingset_eviction(mapping, page);
__delete_from_page_cache(page, shadow, memcg);
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
if (freepage != NULL)
freepage(page);
@@ -694,7 +694,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
cannot_free:
spin_unlock_irqrestore(&mapping->tree_lock, flags);
- mem_cgroup_end_page_stat(memcg);
+ unlock_page_memcg(memcg);
return 0;
}
--
2.7.0
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