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mempolicy: fix refcount leak in mpol_set_shared_policy()

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When shared_policy_replace() fails to allocate new->policy is not freed
correctly by mpol_set_shared_policy().  The problem is that shared
mempolicy code directly call kmem_cache_free() in multiple places where
it is easy to make a mistake.

This patch creates an sp_free wrapper function and uses it. The bug was
introduced pre-git age (IOW, before 2.6.12-rc2).

[mgorman@suse.de: Editted changelog]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro 2012-10-08 16:29:19 -07:00 committed by Linus Torvalds
parent b22d127a39
commit 63f74ca21f
1 changed files with 9 additions and 6 deletions
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15
mm/mempolicy.c
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@ -2157,12 +2157,17 @@ mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
return pol;
}
static void sp_free(struct sp_node *n)
{
mpol_put(n->policy);
kmem_cache_free(sn_cache, n);
}
static void sp_delete(struct shared_policy *sp, struct sp_node *n)
{
pr_debug("deleting %lx-l%lx\n", n->start, n->end);
rb_erase(&n->nd, &sp->root);
mpol_put(n->policy);
kmem_cache_free(sn_cache, n);
sp_free(n);
}
static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
@ -2301,7 +2306,7 @@ int mpol_set_shared_policy(struct shared_policy *info,
}
err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);
if (err && new)
kmem_cache_free(sn_cache, new);
sp_free(new);
return err;
}
@ -2318,9 +2323,7 @@ void mpol_free_shared_policy(struct shared_policy *p)
while (next) {
n = rb_entry(next, struct sp_node, nd);
next = rb_next(&n->nd);
rb_erase(&n->nd, &p->root);
mpol_put(n->policy);
kmem_cache_free(sn_cache, n);
sp_delete(p, n);
}
mutex_unlock(&p->mutex);
}