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authorPaul E. McKenney <paulmck@kernel.org>2023-04-03 16:49:14 -0700
committerPaul E. McKenney <paulmck@kernel.org>2023-05-09 17:26:21 -0700
commitcdfa0f6fa6b7183c062046043b649b9a91e3ac52 (patch)
treef41f5abdf97e0fa3060ac924c0b62be0b5def5a6 /kernel/rcu
parent7e3f926bf4538cb4988b3e3f8bc1cb4a603b2ef6 (diff)
downloadlwn-cdfa0f6fa6b7183c062046043b649b9a91e3ac52.tar.gz
lwn-cdfa0f6fa6b7183c062046043b649b9a91e3ac52.zip
rcu/kvfree: Add debug to check grace periods
This commit adds debugging checks to verify that the required RCU grace period has elapsed for each kvfree_rcu_bulk_data structure that arrives at the kvfree_rcu_bulk() function. These checks make use of that structure's ->gp_snap field, which has been upgraded from an unsigned long to an rcu_gp_oldstate structure. This upgrade reduces the chances of false positives to nearly zero, even on 32-bit systems, for which this structure carries 64 bits of state. Cc: Ziwei Dai <ziwei.dai@unisoc.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c37
1 files changed, 19 insertions, 18 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f52ff7241041..91d75fd6c579 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2756,7 +2756,7 @@ EXPORT_SYMBOL_GPL(call_rcu);
*/
struct kvfree_rcu_bulk_data {
struct list_head list;
- unsigned long gp_snap;
+ struct rcu_gp_oldstate gp_snap;
unsigned long nr_records;
void *records[];
};
@@ -2921,23 +2921,24 @@ kvfree_rcu_bulk(struct kfree_rcu_cpu *krcp,
int i;
debug_rcu_bhead_unqueue(bnode);
-
- rcu_lock_acquire(&rcu_callback_map);
- if (idx == 0) { // kmalloc() / kfree().
- trace_rcu_invoke_kfree_bulk_callback(
- rcu_state.name, bnode->nr_records,
- bnode->records);
-
- kfree_bulk(bnode->nr_records, bnode->records);
- } else { // vmalloc() / vfree().
- for (i = 0; i < bnode->nr_records; i++) {
- trace_rcu_invoke_kvfree_callback(
- rcu_state.name, bnode->records[i], 0);
-
- vfree(bnode->records[i]);
+ if (!WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&bnode->gp_snap))) {
+ rcu_lock_acquire(&rcu_callback_map);
+ if (idx == 0) { // kmalloc() / kfree().
+ trace_rcu_invoke_kfree_bulk_callback(
+ rcu_state.name, bnode->nr_records,
+ bnode->records);
+
+ kfree_bulk(bnode->nr_records, bnode->records);
+ } else { // vmalloc() / vfree().
+ for (i = 0; i < bnode->nr_records; i++) {
+ trace_rcu_invoke_kvfree_callback(
+ rcu_state.name, bnode->records[i], 0);
+
+ vfree(bnode->records[i]);
+ }
}
+ rcu_lock_release(&rcu_callback_map);
}
- rcu_lock_release(&rcu_callback_map);
raw_spin_lock_irqsave(&krcp->lock, flags);
if (put_cached_bnode(krcp, bnode))
@@ -3081,7 +3082,7 @@ kvfree_rcu_drain_ready(struct kfree_rcu_cpu *krcp)
INIT_LIST_HEAD(&bulk_ready[i]);
list_for_each_entry_safe_reverse(bnode, n, &krcp->bulk_head[i], list) {
- if (!poll_state_synchronize_rcu(bnode->gp_snap))
+ if (!poll_state_synchronize_rcu_full(&bnode->gp_snap))
break;
atomic_sub(bnode->nr_records, &krcp->bulk_count[i]);
@@ -3285,7 +3286,7 @@ add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
// Finally insert and update the GP for this page.
bnode->records[bnode->nr_records++] = ptr;
- bnode->gp_snap = get_state_synchronize_rcu();
+ get_state_synchronize_rcu_full(&bnode->gp_snap);
atomic_inc(&(*krcp)->bulk_count[idx]);
return true;