From 0dba1314d4f81115dce711292ec7981d17231064 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 1 Feb 2017 14:05:23 -0800 Subject: scsi, block: fix duplicate bdi name registration crashes 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 Cc: Bart Van Assche Cc: "Martin K. Petersen" Cc: Jan Kara Reported-by: Omar Sandoval Tested-by: Omar Sandoval Signed-off-by: Dan Williams Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- block/genhd.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index d9ccd42f36756..3631cd4802955 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -572,6 +572,20 @@ exit: disk_part_iter_exit(&piter); } +void put_disk_devt(struct disk_devt *disk_devt) +{ + if (disk_devt && atomic_dec_and_test(&disk_devt->count)) + disk_devt->release(disk_devt); +} +EXPORT_SYMBOL(put_disk_devt); + +void get_disk_devt(struct disk_devt *disk_devt) +{ + if (disk_devt) + atomic_inc(&disk_devt->count); +} +EXPORT_SYMBOL(get_disk_devt); + /** * device_add_disk - add partitioning information to kernel list * @parent: parent device for the disk @@ -612,6 +626,13 @@ void device_add_disk(struct device *parent, struct gendisk *disk) disk_alloc_events(disk); + /* + * Take a reference on the devt and assign it to queue since it + * must not be reallocated while the bdi is registered + */ + disk->queue->disk_devt = disk->disk_devt; + get_disk_devt(disk->disk_devt); + /* Register BDI before referencing it from bdev */ bdi = disk->queue->backing_dev_info; bdi_register_owner(bdi, disk_to_dev(disk)); -- cgit v1.2.3