Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
0b9e66762a
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]
[15.187601] btrfs_alloc_tree_block+0xb5/0x3b0 [btrfs]
[15.187601] __btrfs_cow_block+0x138/0x600 [btrfs]
[15.187601] btrfs_cow_block+0x10f/0x230 [btrfs]
[15.187601] btrfs_search_slot+0x55f/0xbc0 [btrfs]
[15.187601] ? lock_is_held_type+0xd7/0x130
[15.187601] btrfs_insert_empty_items+0x2d/0x60 [btrfs]
[15.187601] btrfs_create_pending_block_groups+0x2b3/0x560 [btrfs]
[15.187601] __btrfs_end_transaction+0x36/0x2a0 [btrfs]
[15.192037] flush_space+0x374/0x600 [btrfs]
[15.192037] ? find_held_lock+0x2b/0x80
[15.192037] ? btrfs_async_reclaim_data_space+0x49/0x180 [btrfs]
[15.192037] ? lock_release+0x131/0x2b0
[15.192037] btrfs_async_reclaim_data_space+0x70/0x180 [btrfs]
[15.192037] process_one_work+0x24c/0x5a0
[15.192037] worker_thread+0x4a/0x3d0
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.