Re: [PATCH -stable] block: fix ext_dev_lock lockdep report

[Dan Williams]

On Thu, Jun 11, 2015 at 12:51 AM, Jiri Slaby <jslaby@xxxxxxx> wrote:
> On 06/11/2015, 05:47 AM, Dan Williams wrote:
>>  =================================
>>  [ INFO: inconsistent lock state ]
>>  4.1.0-rc7+ #217 Tainted: G           O
>>  ---------------------------------
>>  inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
>>  swapper/6/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
>>   (ext_devt_lock){+.?...}, at: [<ffffffff8143a60c>] blk_free_devt+0x3c/0x70
>>  {SOFTIRQ-ON-W} state was registered at:
>>    [<ffffffff810bf6b1>] __lock_acquire+0x461/0x1e70
>>    [<ffffffff810c1947>] lock_acquire+0xb7/0x290
>>    [<ffffffff818ac3a8>] _raw_spin_lock+0x38/0x50
>>    [<ffffffff8143a07d>] blk_alloc_devt+0x6d/0xd0  <-- take the lock in process context
>> [..]
>>   [<ffffffff810bf64e>] __lock_acquire+0x3fe/0x1e70
>>   [<ffffffff810c00ad>] ? __lock_acquire+0xe5d/0x1e70
>>   [<ffffffff810c1947>] lock_acquire+0xb7/0x290
>>   [<ffffffff8143a60c>] ? blk_free_devt+0x3c/0x70
>>   [<ffffffff818ac3a8>] _raw_spin_lock+0x38/0x50
>>   [<ffffffff8143a60c>] ? blk_free_devt+0x3c/0x70
>>   [<ffffffff8143a60c>] blk_free_devt+0x3c/0x70    <-- take the lock in softirq
>>   [<ffffffff8143bfec>] part_release+0x1c/0x50
>>   [<ffffffff8158edf6>] device_release+0x36/0xb0
>>   [<ffffffff8145ac2b>] kobject_cleanup+0x7b/0x1a0
>>   [<ffffffff8145aad0>] kobject_put+0x30/0x70
>>   [<ffffffff8158f147>] put_device+0x17/0x20
>>   [<ffffffff8143c29c>] delete_partition_rcu_cb+0x16c/0x180
>>   [<ffffffff8143c130>] ? read_dev_sector+0xa0/0xa0
>>   [<ffffffff810e0e0f>] rcu_process_callbacks+0x2ff/0xa90
>>   [<ffffffff810e0dcf>] ? rcu_process_callbacks+0x2bf/0xa90
>>   [<ffffffff81067e2e>] __do_softirq+0xde/0x600
>>
>> Neil sees this in his tests and it also triggers on pmem driver unbind
>> for the libnvdimm tests.  This fix is on top of an initial fix by Keith
>> for incorrect usage of mutex_lock() in this path: 2da78092dda1 "block:
>> Fix dev_t minor allocation lifetime".  Both this and 2da78092dda1 are
>> candidates for -stable.
>
> And what is *this* in terms of SHA? Thanks.

Whatever it becomes when applied by Jens, i.e. self-referencing.
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