author: yanghui <yanghui.def@bytedance.com> 2021-09-08 18:10:20 -0700
committer: Linus Torvalds <torvalds@linux-foundation.org> 2021-09-08 18:45:53 -0700
commit: 276aeee1c5fc00df700f0782060beae126600472
parent: 79d3705040c3b41075f894fdeeebdcbb46550c63
Commit Summary:
Diffstat:
1 file changed, 13 insertions, 4 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5e90b3fb7794..b44f54768766 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1979,17 +1979,26 @@ unsigned int mempolicy_slab_node(void)
*/
static unsigned offset_il_node(struct mempolicy *pol, unsigned long n)
{
- unsigned nnodes = nodes_weight(pol->nodes);
- unsigned target;
+ nodemask_t nodemask = pol->nodes;
+ unsigned int target, nnodes;
int i;
int nid;
+ /*
+ * The barrier will stabilize the nodemask in a register or on
+ * the stack so that it will stop changing under the code.
+ *
+ * Between first_node() and next_node(), pol->nodes could be changed
+ * by other threads. So we put pol->nodes in a local stack.
+ */
+ barrier();
+ nnodes = nodes_weight(nodemask);
if (!nnodes)
return numa_node_id();
target = (unsigned int)n % nnodes;
- nid = first_node(pol->nodes);
+ nid = first_node(nodemask);
for (i = 0; i < target; i++)
- nid = next_node(nid, pol->nodes);
+ nid = next_node(nid, nodemask);
return nid;
}