Merge branch 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU updates from Paul McKenney:

 - Bitmap parsing support for "all" as an alias for all bits

 - Documentation updates

 - Miscellaneous fixes, including some that overlap into mm and lockdep

 - kvfree_rcu() updates

 - mem_dump_obj() updates, with acks from one of the slab-allocator
   maintainers

 - RCU NOCB CPU updates, including limited deoffloading

 - SRCU updates

 - Tasks-RCU updates

 - Torture-test updates

* 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (78 commits)
  tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline
  rcu-tasks: Make ksoftirqd provide RCU Tasks quiescent states
  rcu: Add missing __releases() annotation
  rcu: Remove obsolete rcu_read_unlock() deadlock commentary
  rcu: Improve comments describing RCU read-side critical sections
  rcu: Create an unrcu_pointer() to remove __rcu from a pointer
  srcu: Early test SRCU polling start
  rcu: Fix various typos in comments
  rcu/nocb: Unify timers
  rcu/nocb: Prepare for fine-grained deferred wakeup
  rcu/nocb: Only cancel nocb timer if not polling
  rcu/nocb: Delete bypass_timer upon nocb_gp wakeup
  rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup
  rcu/nocb: Allow de-offloading rdp leader
  rcu/nocb: Directly call __wake_nocb_gp() from bypass timer
  rcu: Don't penalize priority boosting when there is nothing to boost
  rcu: Point to documentation of ordering guarantees
  rcu: Make rcu_gp_cleanup() be noinline for tracing
  rcu: Restrict RCU_STRICT_GRACE_PERIOD to at most four CPUs
  rcu: Make show_rcu_gp_kthreads() dump rcu_node structures blocking GP
  ...

5 files changed, 22 insertions, 3 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index fcc29e9a3064..c729a4c4a1ac 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -922,7 +922,7 @@ static void __oom_kill_process(struct task_struct *victim, const char *message)
 			continue;
 		}
 		/*
-		 * No kthead_use_mm() user needs to read from the userspace so
+		 * No kthread_use_mm() user needs to read from the userspace so
 		 * we are ok to reap it.
 		 */
 		if (unlikely(p->flags & PF_KTHREAD))
diff --git a/mm/slab.h b/mm/slab.h
index 7b60ef2f32c3..67e06637ff2e 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -634,6 +634,7 @@ struct kmem_obj_info {
 	struct kmem_cache *kp_slab_cache;
 	void *kp_ret;
 	void *kp_stack[KS_ADDRS_COUNT];
+	void *kp_free_stack[KS_ADDRS_COUNT];
 };
 void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page);
 #endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index c126e6f6b5a5..1c673c323baf 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -575,7 +575,7 @@ EXPORT_SYMBOL_GPL(kmem_valid_obj);
  * depends on the type of object and on how much debugging is enabled.
  * For a slab-cache object, the fact that it is a slab object is printed,
  * and, if available, the slab name, return address, and stack trace from
- * the allocation of that object.
+ * the allocation and last free path of that object.
  *
  * This function will splat if passed a pointer to a non-slab object.
  * If you are not sure what type of object you have, you should instead
@@ -620,6 +620,16 @@ void kmem_dump_obj(void *object)
 			break;
 		pr_info("    %pS\n", kp.kp_stack[i]);
 	}
+
+	if (kp.kp_free_stack[0])
+		pr_cont(" Free path:\n");
+
+	for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
+		if (!kp.kp_free_stack[i])
+			break;
+		pr_info("    %pS\n", kp.kp_free_stack[i]);
+	}
+
 }
 EXPORT_SYMBOL_GPL(kmem_dump_obj);
 #endif
diff --git a/mm/slub.c b/mm/slub.c
index 3bc8b940c933..2ee43ff667a5 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4045,6 +4045,7 @@ void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
 	    !(s->flags & SLAB_STORE_USER))
 		return;
 #ifdef CONFIG_SLUB_DEBUG
+	objp = fixup_red_left(s, objp);
 	trackp = get_track(s, objp, TRACK_ALLOC);
 	kpp->kp_ret = (void *)trackp->addr;
 #ifdef CONFIG_STACKTRACE
@@ -4053,6 +4054,13 @@ void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
 		if (!kpp->kp_stack[i])
 			break;
 	}
+
+	trackp = get_track(s, objp, TRACK_FREE);
+	for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) {
+		kpp->kp_free_stack[i] = (void *)trackp->addrs[i];
+		if (!kpp->kp_free_stack[i])
+			break;
+	}
 #endif
 #endif
 }
diff --git a/mm/util.c b/mm/util.c
index a034525e7ba2..99c6cc77de9e 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -983,7 +983,7 @@ int __weak memcmp_pages(struct page *page1, struct page *page2)
  * depends on the type of object and on how much debugging is enabled.
  * For example, for a slab-cache object, the slab name is printed, and,
  * if available, the return address and stack trace from the allocation
- * of that object.
+ * and last free path of that object.
  */
 void mem_dump_obj(void *object)
 {