Commit 6b51e881 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Linus Torvalds
Browse files

mm/list_lru: introduce list_lru_shrink_walk_irq() 

Provide list_lru_shrink_walk_irq() and let it behave like
list_lru_walk_one() except that it locks the spinlock with
spin_lock_irq().  This is used by scan_shadow_nodes() because its lock
nests within the i_pages lock which is acquired with IRQ.  This change
allows to use proper locking promitives instead hand crafted
lock_irq_disable() plus spin_lock().

There is no EXPORT_SYMBOL provided because the current user is in-kernel
only.

Add list_lru_shrink_walk_irq() which acquires the spinlock with the
proper locking primitives.

Link: http://lkml.kernel.org/r/20180716111921.5365-5-bigeasy@linutronix.de


Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarVladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6e018968

include/linux/list_lru.h

+25 −0
Original line number Diff line number Diff line
@@ -166,6 +166,23 @@ unsigned long list_lru_walk_one(struct list_lru *lru, 
				int nid, struct mem_cgroup *memcg,

				list_lru_walk_cb isolate, void *cb_arg,

				unsigned long *nr_to_walk);

/**

 * list_lru_walk_one_irq: walk a list_lru, isolating and disposing freeable items.

 * @lru: the lru pointer.

 * @nid: the node id to scan from.

 * @memcg: the cgroup to scan from.

 * @isolate: callback function that is resposible for deciding what to do with

 *  the item currently being scanned

 * @cb_arg: opaque type that will be passed to @isolate

 * @nr_to_walk: how many items to scan.

 *

 * Same as @list_lru_walk_one except that the spinlock is acquired with

 * spin_lock_irq().

 */

unsigned long list_lru_walk_one_irq(struct list_lru *lru,

				    int nid, struct mem_cgroup *memcg,

				    list_lru_walk_cb isolate, void *cb_arg,

				    unsigned long *nr_to_walk);

unsigned long list_lru_walk_node(struct list_lru *lru, int nid,

				 list_lru_walk_cb isolate, void *cb_arg,

				 unsigned long *nr_to_walk);
@@ -178,6 +195,14 @@ list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc, 
				 &sc->nr_to_scan);

}



static inline unsigned long

list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc,

			 list_lru_walk_cb isolate, void *cb_arg)

{

	return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg,

				     &sc->nr_to_scan);

}



static inline unsigned long

list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,

	      void *cb_arg, unsigned long nr_to_walk)

mm/list_lru.c

+15 −0
Original line number Diff line number Diff line
@@ -282,6 +282,21 @@ list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg, 
}

EXPORT_SYMBOL_GPL(list_lru_walk_one);



unsigned long

list_lru_walk_one_irq(struct list_lru *lru, int nid, struct mem_cgroup *memcg,

		      list_lru_walk_cb isolate, void *cb_arg,

		      unsigned long *nr_to_walk)

{

	struct list_lru_node *nlru = &lru->node[nid];

	unsigned long ret;



	spin_lock_irq(&nlru->lock);

	ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,

				  nr_to_walk);

	spin_unlock_irq(&nlru->lock);

	return ret;

}



unsigned long list_lru_walk_node(struct list_lru *lru, int nid,

				 list_lru_walk_cb isolate, void *cb_arg,

				 unsigned long *nr_to_walk)

mm/workingset.c

+2 −6
Original line number Diff line number Diff line
@@ -483,13 +483,9 @@ out: 
static unsigned long scan_shadow_nodes(struct shrinker *shrinker,

				       struct shrink_control *sc)

{

	unsigned long ret;



	/* list_lru lock nests inside the IRQ-safe i_pages lock */

	local_irq_disable();

	ret = list_lru_shrink_walk(&shadow_nodes, sc, shadow_lru_isolate, NULL);

	local_irq_enable();

	return ret;

	return list_lru_shrink_walk_irq(&shadow_nodes, sc, shadow_lru_isolate,

					NULL);

}



static struct shrinker workingset_shadow_shrinker = {

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