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Commit b18e7e65 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
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[PATCH] slab: fix drain_array() so that it works correctly with the shared_array 



The list_lock also protects the shared array and we call drain_array() with
the shared array.  Therefore we cannot go as far as I wanted to but have to
take the lock in a way so that it also protects the array_cache in
drain_pages.

(Note: maybe we should make the array_cache locking more consistent?  I.e.
always take the array cache lock for shared arrays and disable interrupts
for the per cpu arrays?)

Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 1b55253a

mm/slab.c

+12 −9
Original line number Diff line number Diff line
@@ -3521,7 +3521,8 @@ static void enable_cpucache(struct kmem_cache *cachep) 


/*

 * Drain an array if it contains any elements taking the l3 lock only if

 * necessary.

 * necessary. Note that the l3 listlock also protects the array_cache

 * if drain_array() is used on the shared array.

 */

void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,

			 struct array_cache *ac, int force, int node)
@@ -3532,17 +3533,19 @@ void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3, 
		return;

	if (ac->touched && !force) {

		ac->touched = 0;

	} else if (ac->avail) {

	} else {

		spin_lock_irq(&l3->list_lock);

		if (ac->avail) {

			tofree = force ? ac->avail : (ac->limit + 4) / 5;

			if (tofree > ac->avail)

				tofree = (ac->avail + 1) / 2;

		spin_lock_irq(&l3->list_lock);

			free_block(cachep, ac->entry, tofree, node);

		spin_unlock_irq(&l3->list_lock);

			ac->avail -= tofree;

			memmove(ac->entry, &(ac->entry[tofree]),

				sizeof(void *) * ac->avail);

		}

		spin_unlock_irq(&l3->list_lock);

	}

}



/**