4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ming Lei <[email protected]>


[ Upstream commit 737f98cfe7de8df7433a4d846850aa8efa44bd48 ]

Both q->mq_kobj and sw queues' kobjects should have been initialized
once, instead of doing that each add_disk context.

Also this patch removes clearing of ctx in blk_mq_init_cpu_queues()
because percpu allocator fills zero to allocated variable.

This patch fixes one issue[1] reported from Omar.

[1] kernel wearning when doing unbind/bind on one scsi-mq device

[   19.347924] kobject (ffff8800791ea0b8): tried to init an initialized object, 
something is seriously wrong.
[   19.349781] CPU: 1 PID: 84 Comm: kworker/u8:1 Not tainted 
4.10.0-rc7-00210-g53f39eeaa263 #34
[   19.350686] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
1.10.1-20161122_114906-anatol 04/01/2014
[   19.350920] Workqueue: events_unbound async_run_entry_fn
[   19.350920] Call Trace:
[   19.350920]  dump_stack+0x63/0x83
[   19.350920]  kobject_init+0x77/0x90
[   19.350920]  blk_mq_register_dev+0x40/0x130
[   19.350920]  blk_register_queue+0xb6/0x190
[   19.350920]  device_add_disk+0x1ec/0x4b0
[   19.350920]  sd_probe_async+0x10d/0x1c0 [sd_mod]
[   19.350920]  async_run_entry_fn+0x48/0x150
[   19.350920]  process_one_work+0x1d0/0x480
[   19.350920]  worker_thread+0x48/0x4e0
[   19.350920]  kthread+0x101/0x140
[   19.350920]  ? process_one_work+0x480/0x480
[   19.350920]  ? kthread_create_on_node+0x60/0x60
[   19.350920]  ret_from_fork+0x2c/0x40

Cc: Omar Sandoval <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Tested-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 block/blk-mq-sysfs.c |    4 +---
 block/blk-mq.c       |    4 +++-
 block/blk-mq.h       |    1 +
 3 files changed, 5 insertions(+), 4 deletions(-)

--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -429,7 +429,7 @@ void blk_mq_hctx_kobj_init(struct blk_mq
        kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
 }
 
-static void blk_mq_sysfs_init(struct request_queue *q)
+void blk_mq_sysfs_init(struct request_queue *q)
 {
        struct blk_mq_ctx *ctx;
        int cpu;
@@ -449,8 +449,6 @@ int blk_mq_register_dev(struct device *d
 
        blk_mq_disable_hotplug();
 
-       blk_mq_sysfs_init(q);
-
        ret = kobject_add(&q->mq_kobj, kobject_get(&dev->kobj), "%s", "mq");
        if (ret < 0)
                goto out;
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1707,7 +1707,6 @@ static void blk_mq_init_cpu_queues(struc
                struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
                struct blk_mq_hw_ctx *hctx;
 
-               memset(__ctx, 0, sizeof(*__ctx));
                __ctx->cpu = i;
                spin_lock_init(&__ctx->lock);
                INIT_LIST_HEAD(&__ctx->rq_list);
@@ -1970,6 +1969,9 @@ struct request_queue *blk_mq_init_alloca
        if (!q->queue_ctx)
                goto err_exit;
 
+       /* init q->mq_kobj and sw queues' kobjects */
+       blk_mq_sysfs_init(q);
+
        q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
                                                GFP_KERNEL, set->numa_node);
        if (!q->queue_hw_ctx)
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -50,6 +50,7 @@ static inline struct blk_mq_hw_ctx *blk_
 /*
  * sysfs helpers
  */
+extern void blk_mq_sysfs_init(struct request_queue *q);
 extern int blk_mq_sysfs_register(struct request_queue *q);
 extern void blk_mq_sysfs_unregister(struct request_queue *q);
 extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);


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