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Commit c0a5b560 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

list_lru: organize all list_lrus to list 



To make list_lru memcg aware, we need all list_lrus to be kept on a list
protected by a mutex, so that we could sleep while walking over the
list.

Therefore after this change list_lru_destroy may sleep.  Fortunately,
there is only one user that calls it from an atomic context - it's
put_super - and we can easily fix it by calling list_lru_destroy before
put_super in destroy_locked_super - anyway we don't longer need lrus by
that time.

Another point that should be noted is that list_lru_destroy is allowed
to be called on an uninitialized zeroed-out object, in which case it is
a no-op.  Before this patch this was guaranteed by kfree, but now we
need an explicit check there.

Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ff0b67ef

fs/super.c

+8 −0
Original line number Diff line number Diff line
@@ -282,6 +282,14 @@ void deactivate_locked_super(struct super_block *s) 
		unregister_shrinker(&s->s_shrink);

		fs->kill_sb(s);



		/*

		 * Since list_lru_destroy() may sleep, we cannot call it from

		 * put_super(), where we hold the sb_lock. Therefore we destroy

		 * the lru lists right now.

		 */

		list_lru_destroy(&s->s_dentry_lru);

		list_lru_destroy(&s->s_inode_lru);



		put_filesystem(fs);

		put_super(s);

	} else {

include/linux/list_lru.h

+3 −0
Original line number Diff line number Diff line
@@ -31,6 +31,9 @@ struct list_lru_node { 


struct list_lru {

	struct list_lru_node	*node;

#ifdef CONFIG_MEMCG_KMEM

	struct list_head	list;

#endif

};



void list_lru_destroy(struct list_lru *lru);

mm/list_lru.c

+34 −0
Original line number Diff line number Diff line
@@ -9,6 +9,34 @@ 
#include <linux/mm.h>

#include <linux/list_lru.h>

#include <linux/slab.h>

#include <linux/mutex.h>



#ifdef CONFIG_MEMCG_KMEM

static LIST_HEAD(list_lrus);

static DEFINE_MUTEX(list_lrus_mutex);



static void list_lru_register(struct list_lru *lru)

{

	mutex_lock(&list_lrus_mutex);

	list_add(&lru->list, &list_lrus);

	mutex_unlock(&list_lrus_mutex);

}



static void list_lru_unregister(struct list_lru *lru)

{

	mutex_lock(&list_lrus_mutex);

	list_del(&lru->list);

	mutex_unlock(&list_lrus_mutex);

}

#else

static void list_lru_register(struct list_lru *lru)

{

}



static void list_lru_unregister(struct list_lru *lru)

{

}

#endif /* CONFIG_MEMCG_KMEM */



bool list_lru_add(struct list_lru *lru, struct list_head *item)

{
@@ -137,12 +165,18 @@ int list_lru_init_key(struct list_lru *lru, struct lock_class_key *key) 
		INIT_LIST_HEAD(&lru->node[i].list);

		lru->node[i].nr_items = 0;

	}

	list_lru_register(lru);

	return 0;

}

EXPORT_SYMBOL_GPL(list_lru_init_key);



void list_lru_destroy(struct list_lru *lru)

{

	/* Already destroyed or not yet initialized? */

	if (!lru->node)

		return;

	list_lru_unregister(lru);

	kfree(lru->node);

	lru->node = NULL;

}

EXPORT_SYMBOL_GPL(list_lru_destroy);