[PATCH] mmc: block: Delete gendisk before cleaning up the request queue

[Adrian Hunter]

On 22/03/18 10:43, Shawn Lin wrote:
> On 2018/3/22 16:26, Adrian Hunter wrote:
>> On 22/03/18 09:49, Shawn Lin wrote:
>>> dd if=/dev/urandom of=/dev/mmcblk1 bs=4k count=10000
>>> with a SD card hotplug during transfer reports a warning below:
>>
>> What kernel version / commit was it?
> 
> Actually the log below has it, it is clean : 4.16.0-rc6-next-20180321

Ok so it seems to be coming from this patch in next:

commit a063057d7c731cffa7d10740e8ebc2970df8dbb3
Author: Bart Van Assche <bart.vanassche at wdc.com>
Date:   Wed Feb 28 10:15:33 2018 -0800

    block: Fix a race between request queue removal and the block cgroup controller

    Avoid that the following race can occur:

    blk_cleanup_queue()               blkcg_print_blkgs()
      spin_lock_irq(lock) (1)           spin_lock_irq(blkg->q->queue_lock) (2,5)
        q->queue_lock = &q->__queue_lock (3)
      spin_unlock_irq(lock) (4)
                                        spin_unlock_irq(blkg->q->queue_lock) (6)

    (1) take driver lock;
    (2) busy loop for driver lock;
    (3) override driver lock with internal lock;
    (4) unlock driver lock;
    (5) can take driver lock now;
    (6) but unlock internal lock.

    This change is safe because only the SCSI core and the NVME core keep
    a reference on a request queue after having called blk_cleanup_queue().
    Neither driver accesses any of the removed data structures between its
    blk_cleanup_queue() and blk_put_queue() calls.

    Reported-by: Joseph Qi <joseph.qi at linux.alibaba.com>
    Signed-off-by: Bart Van Assche <bart.vanassche at wdc.com>
    Reviewed-by: Joseph Qi <joseph.qi at linux.alibaba.com>
    Cc: Jan Kara <jack at suse.com>
    Signed-off-by: Jens Axboe <axboe at kernel.dk>


> 
>>
>>>
>>> Remove the disk, partition and bdi sysfs attributes before cleaning
>>> up the request queue associated with the disk.
>>>
>>> [  410.331226] mmc1: card 59b4 removed
>>> [  410.348583] WARNING: CPU: 0 PID: 5 at block/blk-core.c:785
>>> blk_cleanup_queue+0x138/0x140
>>> [  410.349294] Modules linked in:
>>> [  410.349570] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted
>>> 4.16.0-rc6-next-20180321-00004-gc2ad6a7 #263
>>> [  410.350363] Hardware name: Excavator-RK3399 Board (DT)
>>> [  410.350819] Workqueue: events_freezable mmc_rescan
>>> [  410.351242] pstate: 60000005 (nZCv daif -PAN -UAO)
>>> [  410.351663] pc : blk_cleanup_queue+0x138/0x140
>>> [  410.352054] lr : blk_cleanup_queue+0xac/0x140
>>> [  410.352436] sp : ffff0000092cbb90
>>> [  410.352727] x29: ffff0000092cbb90 x28: 0000000000000000
>>> [  410.353195] x27: ffff8000f6f23030 x26: ffff00000904e610
>>> [  410.353662] x25: ffff8000f17cc808 x24: ffff8000f1038200
>>> [  410.354128] x23: 0000000000000060 x22: 0000000000000000
>>> [  410.354595] x21: ffff8000f11748d8 x20: ffff8000f1038200
>>> [  410.355061] x19: ffff8000f1174200 x18: 0000ffff936347d8
>>> [  410.355528] x17: 0000ffff935b93c0 x16: ffff0000081263f8
>>> [  410.355994] x15: 0000000000000000 x14: 0000000000000400
>>> [  410.356461] x13: 0000000000000001 x12: 0000000000000001
>>> [  410.356927] x11: 0000000000000040 x10: ffff8000f2400028
>>> [  410.357393] x9 : ffff8000f2400040 x8 : 0000000000000000
>>> [  410.357860] x7 : ffff8000f6f3a340 x6 : ffff8000f6f3a340
>>> [  410.358326] x5 : ffff8000f2400000 x4 : ffff8000f6f3a340
>>> [  410.358792] x3 : 0000000000000000 x2 : 39c1333e45670800
>>> [  410.359259] x1 : 0000000000000000 x0 : 0000000000000003
>>> [  410.359726] Call trace:
>>> [  410.359943]  blk_cleanup_queue+0x138/0x140
>>> [  410.360305]  mmc_cleanup_queue+0x2c/0x48
>>> [  410.360652]  mmc_blk_remove_req+0x1c/0x98
>>> [  410.361005]  mmc_blk_remove+0x180/0x1c0
>>> [  410.361343]  mmc_bus_remove+0x1c/0x28
>>> [  410.361670]  device_release_driver_internal+0x154/0x1f0
>>> [  410.362128]  device_release_driver+0x14/0x20
>>> [  410.362504]  bus_remove_device+0xc8/0x108
>>> [  410.362858]  device_del+0x120/0x350
>>> [  410.363167]  mmc_remove_card+0x5c/0xb8
>>> [  410.363498]  mmc_sd_detect+0x40/0x78
>>> [  410.363813]  mmc_rescan+0x19c/0x368
>>> [  410.364123]  process_one_work+0x1ac/0x318
>>> [  410.364477]  worker_thread+0x50/0x450
>>> [  410.364801]  kthread+0xf8/0x128
>>> [  410.365081]  ret_from_fork+0x10/0x18
>>> [  410.365395] ---[ end trace 268e87a46c28968c ]---
>>>
>>> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
>>> ---
>>>
>>>   drivers/mmc/core/block.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
>>> index a2b9c25..02485e3 100644
>>> --- a/drivers/mmc/core/block.c
>>> +++ b/drivers/mmc/core/block.c
>>> @@ -2659,7 +2659,6 @@ static void mmc_blk_remove_req(struct mmc_blk_data
>>> *md)
>>>            * from being accepted.
>>>            */
>>>           card = md->queue.card;
>>> -        mmc_cleanup_queue(&md->queue);
>>>           if (md->disk->flags & GENHD_FL_UP) {
>>>               device_remove_file(disk_to_dev(md->disk), &md->force_ro);
>>>               if ((md->area_type & MMC_BLK_DATA_AREA_BOOT) &&
>>> @@ -2669,6 +2668,7 @@ static void mmc_blk_remove_req(struct mmc_blk_data
>>> *md)
>>>                 del_gendisk(md->disk);
>>>           }
>>> +        mmc_cleanup_queue(&md->queue);
>>>           mmc_blk_put(md);
>>>       }
>>>   }
>>>
>>
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> 
>