Re: btrfs lockdep issue

Am 13.07.26 um 14:07 schrieb Christian Borntraeger:
[...]

>   Possible unsafe locking scenario:
>         CPU0                    CPU1
>         ----                    ----
>    lock(&fs_devs->device_list_mutex);
>                                 lock(&fs_info->tree_log_mutex);
>                                 lock(&fs_devs->device_list_mutex);
>    rlock(&type->i_mutex_dir_key#2);
>   *** DEADLOCK ***
> 2 locks held by (udev-worker)/1653:
>   #0: 0000016c727051c8 (uuid_mutex){+.+.}-{3:3}, at: btrfs_control_ioctl+0x102/0x1e0
>   #1: 00000069238564d8 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: device_list_add.constprop.0+0x148/0xc60    

So some additional detauls
-------
            
this was a udev-triggered btrfs device scan (BTRFS_IOC_SCAN_DEV) of
/dev/dm-8. The scanned device belongs to the mounted btrfs root filesystem
(multipath, the path flapped between /dev/mapper/mpathg2 and /dev/dm-8),

---snip---
BTRFS info: devid 1 device path /dev/mapper/mpathg2 changed to /dev/dm-8 scanned by (udev-worker) (1653)
---snip---
            
Could this be due to  commit 2e8b6bc0ab41ce41e6dfcc204b6cc01d5abbc952
("btrfs: avoid unnecessary device path update for the same device")
?