1 files changed, 13 insertions, 21 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1fccb98aa28f..76f460e36f1d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1574,22 +1574,6 @@ static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
         return NOTIFY_OK;
 }
 
-static int blk_mq_hctx_cpu_online(struct blk_mq_hw_ctx *hctx, int cpu)
-{
-        struct request_queue *q = hctx->queue;
-        struct blk_mq_tag_set *set = q->tag_set;
-
-        if (set->tags[hctx->queue_num])
-                return NOTIFY_OK;
-
-        set->tags[hctx->queue_num] = blk_mq_init_rq_map(set, hctx->queue_num);
-        if (!set->tags[hctx->queue_num])
-                return NOTIFY_STOP;
-
-        hctx->tags = set->tags[hctx->queue_num];
-        return NOTIFY_OK;
-}
-
 static int blk_mq_hctx_notify(void *data, unsigned long action,
                               unsigned int cpu)
 {
@@ -1597,8 +1581,11 @@ static int blk_mq_hctx_notify(void *data, unsigned long action,
 
         if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
                 return blk_mq_hctx_cpu_offline(hctx, cpu);
-        else if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
-                return blk_mq_hctx_cpu_online(hctx, cpu);
+
+        /*
+         * In case of CPU online, tags may be reallocated
+         * in blk_mq_map_swqueue() after mapping is updated.
+         */
 
         return NOTIFY_OK;
 }
@@ -1778,6 +1765,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
         unsigned int i;
         struct blk_mq_hw_ctx *hctx;
         struct blk_mq_ctx *ctx;
+        struct blk_mq_tag_set *set = q->tag_set;
 
         queue_for_each_hw_ctx(q, hctx, i) {
                 cpumask_clear(hctx->cpumask);
@@ -1806,16 +1794,20 @@ static void blk_mq_map_swqueue(struct request_queue *q)
                  * disable it and free the request entries.
                  */
                 if (!hctx->nr_ctx) {
-                        struct blk_mq_tag_set *set = q->tag_set;
-
                         if (set->tags[i]) {
                                 blk_mq_free_rq_map(set, set->tags[i], i);
                                 set->tags[i] = NULL;
-                                hctx->tags = NULL;
                         }
+                        hctx->tags = NULL;
                         continue;
                 }
 
+                /* unmapped hw queue can be remapped after CPU topo changed */
+                if (!set->tags[i])
+                        set->tags[i] = blk_mq_init_rq_map(set, i);
+                hctx->tags = set->tags[i];
+                WARN_ON(!hctx->tags);
+
                 /*
                  * Set the map size to the number of mapped software queues.
                  * This is more accurate and more efficient than looping