Re: [PATCH] fix memory leak in mm/slab.c::alloc_kmemlist() (try #3)

Christoph Lameter
2006-03-22T01:52:57Z

On Tue, 21 Mar 2006, Andrew Morton wrote:

> Well that's a big pickle. How about allocating everything first, saving it
> locally then, if that all worked out, install it?

That wont work for the tuning case. We need to know somehow if we are
updating or creating a new kmemlist.

But there is so much messy stuff in there. Maybe we should start with a
cleanup patch to increase our comprehension of the situation?

alloc_kmemlist: Some cleanup in preparation for a real memory leak fix

Inspired by Jesper Juhl's patch from today

1. Get rid of err
We do not set it to anything else but zero.

2. Drop the CONFIG_NUMA stuff.
There are definitions for alloc_alien_cache and free_alien_cache()
that do the right thing for the non NUMA case.

3. Better naming of variables.

4. Remove redundant cachep->nodelists[node] expressions.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>

Index: linux-2.6.16-rc6-mm2/mm/slab.c
===================================================================
--- linux-2.6.16-rc6-mm2.orig/mm/slab.c 2006-03-21 17:45:02.000000000 -0800
+++ linux-2.6.16-rc6-mm2/mm/slab.c 2006-03-21 17:49:16.000000000 -0800
@@ -3421,37 +3421,38 @@ static int alloc_kmemlist(struct kmem_ca
{
int node;
struct kmem_list3 *l3;
- int err = 0;
+ struct array_cache *new_shared;
+ struct array_cache **new_alien;

for_each_online_node(node) {
- struct array_cache *nc = NULL, *new;
- struct array_cache **new_alien = NULL;
-#ifdef CONFIG_NUMA
+
new_alien = alloc_alien_cache(node, cachep->limit);
if (!new_alien)
goto fail;
-#endif
- new = alloc_arraycache(node, cachep->shared*cachep->batchcount,
+
+ new_shared = alloc_arraycache(node, cachep->shared*cachep->batchcount,
0xbaadf00d);
- if (!new)
+ if (!new_shared)
goto fail;
+
l3 = cachep->nodelists[node];
if (l3) {
+ struct array_cache *shared = l3->shared;
+
spin_lock_irq(&l3->list_lock);

- nc = cachep->nodelists[node]->shared;
- if (nc)
- free_block(cachep, nc->entry, nc->avail, node);
+ if (shared)
+ free_block(cachep, shared->entry, shared->avail, node);

- l3->shared = new;
- if (!cachep->nodelists[node]->alien) {
+ l3->shared = new_shared;
+ if (!l3->alien) {
l3->alien = new_alien;
new_alien = NULL;
}
l3->free_limit = (1 + nr_cpus_node(node)) *
cachep->batchcount + cachep->num;
spin_unlock_irq(&l3->list_lock);
- kfree(nc);
+ kfree(shared);
free_alien_cache(new_alien);
continue;
}
@@ -3462,16 +3463,15 @@ static int alloc_kmemlist(struct kmem_ca
kmem_list3_init(l3);
l3->next_reap = jiffies + REAPTIMEOUT_LIST3 +
((unsigned long)cachep) % REAPTIMEOUT_LIST3;
- l3->shared = new;
+ l3->shared = new_shared;
l3->alien = new_alien;
l3->free_limit = (1 + nr_cpus_node(node)) *
cachep->batchcount + cachep->num;
cachep->nodelists[node] = l3;
}
- return err;
+ return 0;
fail:
- err = -ENOMEM;
- return err;
+ return -ENOMEM;
}

struct ccupdate_struct {