Merge tag 'v4.19.82' into v4.19-rt

This is the 4.19.82 stable release

1 files changed, 11 insertions, 2 deletions

diff --git a/mm/slub.c b/mm/slub.c
index 2240b51a0549..81c32ceab228 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4874,7 +4874,17 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
 		}
 	}
 
-	get_online_mems();
+	/*
+	 * It is impossible to take "mem_hotplug_lock" here with "kernfs_mutex"
+	 * already held which will conflict with an existing lock order:
+	 *
+	 * mem_hotplug_lock->slab_mutex->kernfs_mutex
+	 *
+	 * We don't really need mem_hotplug_lock (to hold off
+	 * slab_mem_going_offline_callback) here because slab's memory hot
+	 * unplug code doesn't destroy the kmem_cache->node[] data.
+	 */
+
 #ifdef CONFIG_SLUB_DEBUG
 	if (flags & SO_ALL) {
 		struct kmem_cache_node *n;
@@ -4915,7 +4925,6 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
 			x += sprintf(buf + x, " N%d=%lu",
 					node, nodes[node]);
 #endif
-	put_online_mems();
 	kfree(nodes);
 	return x + sprintf(buf + x, "\n");
 }