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SubjectRe: [patch 3/4] mempolicy: add MPOL_F_STATIC_NODES flag
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On Mon, 2008-02-11 at 11:56 -0800, David Rientjes wrote: 
> On Tue, 12 Feb 2008, KOSAKI Motohiro wrote:
>
> > > @@ -218,21 +167,27 @@ static struct mempolicy *mpol_new(enum mempolicy_mode mode,
> > > return ERR_PTR(-ENOMEM);
> > > flags &= MPOL_MODE_FLAGS;
> > > atomic_set(&policy->refcnt, 1);
> > > + cpuset_update_task_memory_state();
> > > + nodes_and(cpuset_context_nmask, *nodes, cpuset_current_mems_allowed);
> > > switch (mode) {
> > > case MPOL_INTERLEAVE:
> > > - policy->v.nodes = *nodes;
> > > + if (nodes_empty(*nodes))
> > > + return ERR_PTR(-EINVAL);
> >
> > need kmem_cache_free(policy_cache, policy) before return?
> >
>
> Very good catch!
>
>
>
> mempolicy: fix policy memory leak in mpol_new()
>
> If mpol_new() cannot setup a new mempolicy because of an invalid argument
> provided by the user, avoid leaking the mempolicy that has been dynamically
> allocated.
>
> Reported by KOSAKI Motohiro.
>
> Cc: Paul Jackson <pj@sgi.com>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
> Cc: Andi Kleen <ak@suse.de>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
> mm/mempolicy.c | 10 +++++-----
> 1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -171,13 +171,11 @@ static struct mempolicy *mpol_new(enum mempolicy_mode mode,
> nodes_and(cpuset_context_nmask, *nodes, cpuset_current_mems_allowed);
> switch (mode) {
> case MPOL_INTERLEAVE:
> - if (nodes_empty(*nodes))
> - return ERR_PTR(-EINVAL);
> - policy->v.nodes = cpuset_context_nmask;
> - if (nodes_weight(policy->v.nodes) == 0) {
> + if (nodes_empty(*nodes) || nodes_empty(cpuset_context_nmask)) {
> kmem_cache_free(policy_cache, policy);
> return ERR_PTR(-EINVAL);
> }
> + policy->v.nodes = cpuset_context_nmask;
> break;
> case MPOL_PREFERRED:
> policy->v.preferred_node = first_node(cpuset_context_nmask);
> @@ -185,8 +183,10 @@ static struct mempolicy *mpol_new(enum mempolicy_mode mode,
> policy->v.preferred_node = -1;
> break;
> case MPOL_BIND:
> - if (nodes_empty(*nodes))
> + if (nodes_empty(*nodes)) {
> + kmem_cache_free(policy_cache, policy);
> return ERR_PTR(-EINVAL);
> + }
> policy->v.zonelist = bind_zonelist(&cpuset_context_nmask);
> if (IS_ERR(policy->v.zonelist)) {
> void *error_code = policy->v.zonelist;

With this patch, we now have 3 error paths from mpol_new that need to
free the mempolicy struct. How about consolidating them with something
like this [uncompiled/untested]:

PATCH mempolicy - consolidate mpol_new() error paths

Use common error path in mpol_new() for errors that we discover
after allocation the new mempolicy structure. Free the mempolicy
in the common error path.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

mm/mempolicy.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

Index: Linux/mm/mempolicy.c
===================================================================
--- Linux.orig/mm/mempolicy.c 2008-02-12 15:18:12.000000000 -0700
+++ Linux/mm/mempolicy.c 2008-02-12 15:22:07.000000000 -0700
@@ -156,6 +156,7 @@ static struct mempolicy *mpol_new(enum m
{
struct mempolicy *policy;
nodemask_t cpuset_context_nmask;
+ void *error_code = ERR_PTR(-EINVAL);

pr_debug("setting mode %d flags %d nodes[0] %lx\n",
mode, flags, nodes ? nodes_addr(*nodes)[0] : -1);
@@ -172,8 +173,7 @@ static struct mempolicy *mpol_new(enum m
switch (mode) {
case MPOL_INTERLEAVE:
if (nodes_empty(*nodes) || nodes_empty(cpuset_context_nmask)) {
- kmem_cache_free(policy_cache, policy);
- return ERR_PTR(-EINVAL);
+ goto free_mpol;
}
policy->v.nodes = cpuset_context_nmask;
break;
@@ -184,14 +184,12 @@ static struct mempolicy *mpol_new(enum m
break;
case MPOL_BIND:
if (nodes_empty(*nodes)) {
- kmem_cache_free(policy_cache, policy);
- return ERR_PTR(-EINVAL);
+ goto free_mpol;
}
policy->v.zonelist = bind_zonelist(&cpuset_context_nmask);
if (IS_ERR(policy->v.zonelist)) {
- void *error_code = policy->v.zonelist;
- kmem_cache_free(policy_cache, policy);
- return error_code;
+ error_code = policy->v.zonelist;
+ goto free_mpol;
}
break;
default:
@@ -201,6 +199,10 @@ static struct mempolicy *mpol_new(enum m
policy->cpuset_mems_allowed = cpuset_mems_allowed(current);
policy->user_nodemask = *nodes;
return policy;
+
+free_mpol:
+ kmem_cache_free(policy_cache, policy);
+ return error_code;
}

static void gather_stats(struct page *, void *, int pte_dirty);



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