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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: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2006-03-22 00:09:07 -08:00 committed by Linus Torvalds
parent 1b55253a7f
commit b18e7e654d
1 changed files with 12 additions and 9 deletions
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21
mm/slab.c
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@ -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)
@ -3532,16 +3533,18 @@ void drain_array(struct kmem_cache *cachep, struct kmem_list3 *l3,
return;
if (ac->touched && !force) {
ac->touched = 0;
} else if (ac->avail) {
tofree = force ? ac->avail : (ac->limit + 4) / 5;
if (tofree > ac->avail)
tofree = (ac->avail + 1) / 2;
} else {
spin_lock_irq(&l3->list_lock);
free_block(cachep, ac->entry, tofree, node);
if (ac->avail) {
tofree = force ? ac->avail : (ac->limit + 4) / 5;
if (tofree > ac->avail)
tofree = (ac->avail + 1) / 2;
free_block(cachep, ac->entry, tofree, node);
ac->avail -= tofree;
memmove(ac->entry, &(ac->entry[tofree]),
sizeof(void *) * ac->avail);
}
spin_unlock_irq(&l3->list_lock);
ac->avail -= tofree;
memmove(ac->entry, &(ac->entry[tofree]),
sizeof(void *) * ac->avail);
}
}