rcu/kvfree: Avoid freeing new kfree_rcu() memory after old grace period

[platform/kernel/linux-starfive.git] / kernel / rcu / tree.c

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ce34ca0..d03122f 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3099,6 +3099,18 @@ need_offload_krc(struct kfree_rcu_cpu *krcp)
        return !!krcp->head;
 }
 
+static bool
+need_wait_for_krwp_work(struct kfree_rcu_cpu_work *krwp)
+{
+       int i;
+
+       for (i = 0; i < FREE_N_CHANNELS; i++)
+               if (krwp->bkvhead_free[i])
+                       return true;
+
+       return !!krwp->head_free;
+}
+
 static void
 schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
 {
@@ -3130,14 +3142,13 @@ static void kfree_rcu_monitor(struct work_struct *work)
        for (i = 0; i < KFREE_N_BATCHES; i++) {
                struct kfree_rcu_cpu_work *krwp = &(krcp->krw_arr[i]);
 
-               // Try to detach bkvhead or head and attach it over any
-               // available corresponding free channel. It can be that
-               // a previous RCU batch is in progress, it means that
-               // immediately to queue another one is not possible so
-               // in that case the monitor work is rearmed.
-               if ((krcp->bkvhead[0] && !krwp->bkvhead_free[0]) ||
-                       (krcp->bkvhead[1] && !krwp->bkvhead_free[1]) ||
-                               (krcp->head && !krwp->head_free)) {
+               // Try to detach bulk_head or head and attach it, only when
+               // all channels are free.  Any channel is not free means at krwp
+               // there is on-going rcu work to handle krwp's free business.
+               if (need_wait_for_krwp_work(krwp))
+                       continue;
+
+               if (need_offload_krc(krcp)) {
                        // Channel 1 corresponds to the SLAB-pointer bulk path.
                        // Channel 2 corresponds to vmalloc-pointer bulk path.
                        for (j = 0; j < FREE_N_CHANNELS; j++) {