Commit 81f8c3a4 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

mm: memcontrol: generalize locking for the page->mem_cgroup binding 



These patches tag the page cache radix tree eviction entries with the
memcg an evicted page belonged to, thus making per-cgroup LRU reclaim
work properly and be as adaptive to new cache workingsets as global
reclaim already is.

This should have been part of the original thrash detection patch
series, but was deferred due to the complexity of those patches.

This patch (of 5):

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.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0db2cb8d

fs/buffer.c

+7 −7
Original line number Diff line number Diff line
@@ -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);

	}

fs/xfs/xfs_aops.c

+4 −4
Original line number Diff line number Diff line
@@ -1978,10 +1978,10 @@ 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);
@@ -1998,7 +1998,7 @@ 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;

include/linux/memcontrol.h

+11 −5
Original line number Diff line number Diff line
@@ -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)

{

}

mm/filemap.c

+6 −6
Original line number Diff line number Diff line
@@ -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)
@@ -263,11 +263,11 @@ 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);
@@ -561,7 +561,7 @@ 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);
@@ -576,7 +576,7 @@ 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)

mm/memcontrol.c

+14 −20
Original line number Diff line number Diff line
@@ -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();

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