CVE-2022-49079: In the Linux kernel, the following vulnerability has been resolved:  btrfs: zoned: traverse devices under chunk_mutex in btrfs_can_activate_zone  btrfs_can_activate_zone() can be called with the device_list_mutex already held, which will lead to a deadlock:  insert_dev_extents() // Takes device_list_mutex `-> insert_dev_extent()  `-> btrfs_insert_empty_item()   `-> btrfs_insert_empty_items()    `-> btrfs_search_slot()     `-> btrfs_cow_block()      `-> __btrfs_cow_block()       `-> btrfs_alloc_tree_block()        `-> btrfs_reserve_extent()         `-> find_free_extent()          `-> find_free_extent_update_loop()           `-> can_allocate_chunk()            `-> btrfs_can_activate_zone() // Takes device_list_mutex again  Instead of using the RCU on fs_devices->device_list we can use fs_devices->alloc_list, protected by the chunk_mutex to traverse the list of active devices.  We are in the chunk allocation thread. The newer chunk allocation happens from the devices in the fs_device->alloc_list protected by the chunk_mutex.    btrfs_create_chunk()     lockdep_assert_held(&info->chunk_mutex);     gather_device_info       list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list)  Also, a device that reappears after the mount won't join the alloc_list yet and, it will be in the dev_list, which we don't want to consider in the context of the chunk alloc.    [15.166572] WARNING: possible recursive locking detected   [15.167117] 5.17.0-rc6-dennis #79 Not tainted   [15.167487] --------------------------------------------   [15.167733] kworker/u8:3/146 is trying to acquire lock:   [15.167733] ffff888102962ee0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: find_free_extent+0x15a/0x14f0 [btrfs]   [15.167733]   [15.167733] but task is already holding lock:   [15.167733] ffff888102962ee0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_create_pending_block_groups+0x20a/0x560 [btrfs]   [15.167733]   [15.167733] other info that might help us debug this:   [15.167733]  Possible unsafe locking scenario:   [15.167733]   [15.171834]        CPU0   [15.171834]        ----   [15.171834]   lock(&fs_devs->device_list_mutex);   [15.171834]   lock(&fs_devs->device_list_mutex);   [15.171834]   [15.171834]  *** DEADLOCK ***   [15.171834]   [15.171834]  May be due to missing lock nesting notation   [15.171834]   [15.171834] 5 locks held by kworker/u8:3/146:   [15.171834]  #0: ffff888100050938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1c3/0x5a0   [15.171834]  #1: ffffc9000067be80 ((work_completion)(&fs_info->async_data_reclaim_work)){+.+.}-{0:0}, at: process_one_work+0x1c3/0x5a0   [15.176244]  #2: ffff88810521e620 (sb_internal){.+.+}-{0:0}, at: flush_space+0x335/0x600 [btrfs]   [15.176244]  #3: ffff888102962ee0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_create_pending_block_groups+0x20a/0x560 [btrfs]   [15.176244]  #4: ffff8881152e4b78 (btrfs-dev-00){++++}-{3:3}, at: __btrfs_tree_lock+0x27/0x130 [btrfs]   [15.179641]   [15.179641] stack backtrace:   [15.179641] CPU: 1 PID: 146 Comm: kworker/u8:3 Not tainted 5.17.0-rc6-dennis #79   [15.179641] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014   [15.179641] Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]   [15.179641] Call Trace:   [15.179641]  <TASK>   [15.179641]  dump_stack_lvl+0x45/0x59   [15.179641]  __lock_acquire.cold+0x217/0x2b2   [15.179641]  lock_acquire+0xbf/0x2b0   [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]   [15.183838]  __mutex_lock+0x8e/0x970   [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]   [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]   [15.183838]  ? lock_is_held_type+0xd7/0x130   [15.183838]  ? find_free_extent+0x15a/0x14f0 [btrfs]   [15.183838]  find_free_extent+0x15a/0x14f0 [btrfs]   [15.183838]  ? _raw_spin_unlock+0x24/0x40   [15.183838]  ? btrfs_get_alloc_profile+0x106/0x230 [btrfs]   [15.187601]  btrfs_reserve_extent+0x131/0x260 [btrfs]   [15. ---truncated---