linux-kernel - Re: [PATCH v3] scsi, block: fix duplicate bdi name registration crashes

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Date:   Wed, 1 Feb 2017 14:43:19 -0800
From:   Jens Axboe <axboe@...nel.dk>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-block@...r.kernel.org, Jan Kara <jack@...e.cz>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        Omar Sandoval <osandov@...ndov.com>,
        Omar Sandoval <osandov@...com>
Subject: Re: [PATCH v3] scsi, block: fix duplicate bdi name registration
 crashes

On 02/01/2017 02:40 PM, Dan Williams wrote:
> On Wed, Feb 1, 2017 at 2:35 PM, Jens Axboe <axboe@...nel.dk> wrote:
>> On 02/01/2017 02:05 PM, Dan Williams wrote:
>>> Warnings of the following form occur because scsi reuses a devt number
>>> while the block layer still has it referenced as the name of the bdi
>>> [1]:
>>>
>>>  WARNING: CPU: 1 PID: 93 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
>>>  sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:192'
>>>  [..]
>>>  Call Trace:
>>>   dump_stack+0x86/0xc3
>>>   __warn+0xcb/0xf0
>>>   warn_slowpath_fmt+0x5f/0x80
>>>   ? kernfs_path_from_node+0x4f/0x60
>>>   sysfs_warn_dup+0x62/0x80
>>>   sysfs_create_dir_ns+0x77/0x90
>>>   kobject_add_internal+0xb2/0x350
>>>   kobject_add+0x75/0xd0
>>>   device_add+0x15a/0x650
>>>   device_create_groups_vargs+0xe0/0xf0
>>>   device_create_vargs+0x1c/0x20
>>>   bdi_register+0x90/0x240
>>>   ? lockdep_init_map+0x57/0x200
>>>   bdi_register_owner+0x36/0x60
>>>   device_add_disk+0x1bb/0x4e0
>>>   ? __pm_runtime_use_autosuspend+0x5c/0x70
>>>   sd_probe_async+0x10d/0x1c0
>>>   async_run_entry_fn+0x39/0x170
>>>
>>> This is a brute-force fix to pass the devt release information from
>>> sd_probe() to the locations where we register the bdi,
>>> device_add_disk(), and unregister the bdi, blk_cleanup_queue().
>>>
>>> Thanks to Omar for the quick reproducer script [2]. This patch survives
>>> where an unmodified kernel fails in a few seconds.
>>
>> What is the patch against? Doesn't seem to apply cleanly for me on
>> master, nor the 4.11 block tree.
>>
> 
> I built it on top of Jan's bdi fixes series [1]. I can rebase to
> block/for-next, just let me know which patches you want to take first.
> 
> [1]: http://marc.info/?l=linux-block&m=148586843819160&w=2

Ah, no that's fine, we'll just pull Jan's stuff in first. Makes sense.

-- 
Jens Axboe