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SubjectRe: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
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On 01/29/2017 05:58 AM, 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.
>
> [1]: https://marc.info/?l=linux-scsi&m=147116857810716&w=4
> [2]: http://marc.info/?l=linux-block&m=148554717109098&w=2
>
> Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
> Cc: Bart Van Assche <bart.vanassche@sandisk.com>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Jens Axboe <axboe@kernel.dk>
> Reported-by: Omar Sandoval <osandov@osandov.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> block/blk-core.c | 1 +
> block/genhd.c | 7 +++++++
> drivers/scsi/sd.c | 41 +++++++++++++++++++++++++++++++++--------
> include/linux/blkdev.h | 1 +
> include/linux/genhd.h | 17 +++++++++++++++++
> 5 files changed, 59 insertions(+), 8 deletions(-)
>
Please check the patchset from Jan Kara (cf 'BDI lifetime fix' on
linux-block), which attempts to solve the same problem.

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

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