[dpdk-dev] [PATCH] mem: fix undefined behavior in NUMA code

[Anatoly Burakov <anatoly.burakov@intel.com>]

When NUMA-aware hugepages config option is set, we rely on
libnuma to tell the kernel to allocate hugepages on a specific
NUMA node. However, we allocate node mask before we check if
NUMA is available in the first place, which, according to
the manpage [1], causes undefined behaviour.

Fix by only using nodemask when we have NUMA available.

[1] https://linux.die.net/man/3/numa_alloc_onnode

Bugzilla ID: 20

Fixes: 1b72605d2416 ("mem: balanced allocation of hugepages")
Cc: i.maximets@samsung.com
Cc: stable@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/linuxapp/eal/eal_memory.c | 28 ++++++++++++++----------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
index dbf19499e..4976eeacd 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -263,7 +263,7 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi,
 	int node_id = -1;
 	int essential_prev = 0;
 	int oldpolicy;
-	struct bitmask *oldmask = numa_allocate_nodemask();
+	struct bitmask *oldmask = NULL;
 	bool have_numa = true;
 	unsigned long maxnode = 0;
 
@@ -275,6 +275,7 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi,
 
 	if (have_numa) {
 		RTE_LOG(DEBUG, EAL, "Trying to obtain current memory policy.\n");
+		oldmask = numa_allocate_nodemask();
 		if (get_mempolicy(&oldpolicy, oldmask->maskp,
 				  oldmask->size + 1, 0, 0) < 0) {
 			RTE_LOG(ERR, EAL,
@@ -390,19 +391,22 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct hugepage_info *hpi,
 
 out:
 #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
-	if (maxnode) {
-		RTE_LOG(DEBUG, EAL,
-			"Restoring previous memory policy: %d\n", oldpolicy);
-		if (oldpolicy == MPOL_DEFAULT) {
-			numa_set_localalloc();
-		} else if (set_mempolicy(oldpolicy, oldmask->maskp,
-					 oldmask->size + 1) < 0) {
-			RTE_LOG(ERR, EAL, "Failed to restore mempolicy: %s\n",
-				strerror(errno));
-			numa_set_localalloc();
+	if (have_numa) {
+		if (maxnode) {
+			RTE_LOG(DEBUG, EAL,
+				"Restoring previous memory policy: %d\n",
+					oldpolicy);
+			if (oldpolicy == MPOL_DEFAULT) {
+				numa_set_localalloc();
+			} else if (set_mempolicy(oldpolicy, oldmask->maskp,
+						 oldmask->size + 1) < 0) {
+				RTE_LOG(ERR, EAL, "Failed to restore mempolicy: %s\n",
+					strerror(errno));
+				numa_set_localalloc();
+			}
 		}
+		numa_free_cpumask(oldmask);
 	}
-	numa_free_cpumask(oldmask);
 #endif
 	return i;
 }
-- 
2.17.1