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Zhihao Cheng 8111964f1b dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata Following concurrent processes: P1(drop cache) P2(kworker) drop_caches_sysctl_handler drop_slab shrink_slab down_read(&shrinker_rwsem) - LOCK A do_shrink_slab super_cache_scan prune_icache_sb dispose_list evict ext4_evict_inode ext4_clear_inode ext4_discard_preallocations ext4_mb_load_buddy_gfp ext4_mb_init_cache ext4_read_block_bitmap_nowait ext4_read_bh_nowait submit_bh dm_submit_bio do_worker process_deferred_bios commit metadata_operation_failed dm_pool_abort_metadata down_write(&pmd->root_lock) - LOCK B __destroy_persistent_data_objects dm_block_manager_destroy dm_bufio_client_destroy unregister_shrinker down_write(&shrinker_rwsem) thin_map \| dm_thin_find_block ↓ down_read(&pmd->root_lock) --> ABBA deadlock , which triggers hung task: [ 76.974820] INFO: task kworker/u4:3:63 blocked for more than 15 seconds. [ 76.976019] Not tainted 6.1.0-rc4-00011-g8f17dd350364-dirty #910 [ 76.978521] task:kworker/u4:3 state:D stack:0 pid:63 ppid:2 [ 76.978534] Workqueue: dm-thin do_worker [ 76.978552] Call Trace: [ 76.978564] __schedule+0x6ba/0x10f0 [ 76.978582] schedule+0x9d/0x1e0 [ 76.978588] rwsem_down_write_slowpath+0x587/0xdf0 [ 76.978600] down_write+0xec/0x110 [ 76.978607] unregister_shrinker+0x2c/0xf0 [ 76.978616] dm_bufio_client_destroy+0x116/0x3d0 [ 76.978625] dm_block_manager_destroy+0x19/0x40 [ 76.978629] __destroy_persistent_data_objects+0x5e/0x70 [ 76.978636] dm_pool_abort_metadata+0x8e/0x100 [ 76.978643] metadata_operation_failed+0x86/0x110 [ 76.978649] commit+0x6a/0x230 [ 76.978655] do_worker+0xc6e/0xd90 [ 76.978702] process_one_work+0x269/0x630 [ 76.978714] worker_thread+0x266/0x630 [ 76.978730] kthread+0x151/0x1b0 [ 76.978772] INFO: task test.sh:2646 blocked for more than 15 seconds. [ 76.979756] Not tainted 6.1.0-rc4-00011-g8f17dd350364-dirty #910 [ 76.982111] task:test.sh state:D stack:0 pid:2646 ppid:2459 [ 76.982128] Call Trace: [ 76.982139] __schedule+0x6ba/0x10f0 [ 76.982155] schedule+0x9d/0x1e0 [ 76.982159] rwsem_down_read_slowpath+0x4f4/0x910 [ 76.982173] down_read+0x84/0x170 [ 76.982177] dm_thin_find_block+0x4c/0xd0 [ 76.982183] thin_map+0x201/0x3d0 [ 76.982188] __map_bio+0x5b/0x350 [ 76.982195] dm_submit_bio+0x2b6/0x930 [ 76.982202] __submit_bio+0x123/0x2d0 [ 76.982209] submit_bio_noacct_nocheck+0x101/0x3e0 [ 76.982222] submit_bio_noacct+0x389/0x770 [ 76.982227] submit_bio+0x50/0xc0 [ 76.982232] submit_bh_wbc+0x15e/0x230 [ 76.982238] submit_bh+0x14/0x20 [ 76.982241] ext4_read_bh_nowait+0xc5/0x130 [ 76.982247] ext4_read_block_bitmap_nowait+0x340/0xc60 [ 76.982254] ext4_mb_init_cache+0x1ce/0xdc0 [ 76.982259] ext4_mb_load_buddy_gfp+0x987/0xfa0 [ 76.982263] ext4_discard_preallocations+0x45d/0x830 [ 76.982274] ext4_clear_inode+0x48/0xf0 [ 76.982280] ext4_evict_inode+0xcf/0xc70 [ 76.982285] evict+0x119/0x2b0 [ 76.982290] dispose_list+0x43/0xa0 [ 76.982294] prune_icache_sb+0x64/0x90 [ 76.982298] super_cache_scan+0x155/0x210 [ 76.982303] do_shrink_slab+0x19e/0x4e0 [ 76.982310] shrink_slab+0x2bd/0x450 [ 76.982317] drop_slab+0xcc/0x1a0 [ 76.982323] drop_caches_sysctl_handler+0xb7/0xe0 [ 76.982327] proc_sys_call_handler+0x1bc/0x300 [ 76.982331] proc_sys_write+0x17/0x20 [ 76.982334] vfs_write+0x3d3/0x570 [ 76.982342] ksys_write+0x73/0x160 [ 76.982347] __x64_sys_write+0x1e/0x30 [ 76.982352] do_syscall_64+0x35/0x80 [ 76.982357] entry_SYSCALL_64_after_hwframe+0x63/0xcd Function metadata_operation_failed() is called when operations failed on dm pool metadata, dm pool will destroy and recreate metadata. So, shrinker will be unregistered and registered, which could down write shrinker_rwsem under pmd_write_lock. Fix it by allocating dm_block_manager before locking pmd->root_lock and destroying old dm_block_manager after unlocking pmd->root_lock, then old dm_block_manager is replaced with new dm_block_manager under pmd->root_lock. So, shrinker register/unregister could be done without holding pmd->root_lock. Fetch a reproducer in [Link]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=216676 Cc: stable@vger.kernel.org #v5.2+ Fixes: `e49e582965` ("dm thin: add read only and fail io modes") Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>		2022-12-01 11:41:40 -05:00
arch	- ioremap: mask out the bits which are not part of the physical address	2022-11-27 11:59:14 -08:00
block	block-6.1-2022-11-25	2022-11-25 17:50:57 -08:00
certs	certs: make system keyring depend on built-in x509 parser	2022-09-24 04:31:18 +09:00
crypto	treewide: use get_random_bytes() when possible	2022-10-11 17:42:58 -06:00
Documentation	Char/Misc driver fixes for 6.1-rc7	2022-11-27 12:17:10 -08:00
drivers	dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata	2022-12-01 11:41:40 -05:00
fs	Amir's copy_file_range() fix	2022-11-27 12:40:06 -08:00
include	Amir's copy_file_range() fix	2022-11-27 12:40:06 -08:00
init	init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash	2022-11-22 22:42:38 +09:00
io_uring	io_uring: clear TIF_NOTIFY_SIGNAL if set and task_work not available	2022-11-25 10:55:08 -07:00
ipc	ipc/shm: call underlying open/close vm_ops	2022-11-22 18:50:42 -08:00
kernel	- Two more fixes to the perf sigtrap handling:	2022-11-27 11:53:41 -08:00
lib	Char/Misc driver fixes for 6.1-rc7	2022-11-27 12:17:10 -08:00
LICENSES	LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers	2021-12-16 14:33:10 +01:00
mm	24 hotfixes. 8 marked cc:stable and 16 for post-6.0 issues.	2022-11-25 10:18:25 -08:00
net	Networking fixes for 6.1-rc7, including fixes from rxrpc, netfilter and	2022-11-24 11:19:20 -08:00
rust	Kbuild: add Rust support	2022-09-28 09:02:20 +02:00
samples	VFIO updates for v6.1-rc1	2022-10-12 14:46:48 -07:00
scripts	- Handle different output of readelf on different distros running	2022-11-27 12:08:17 -08:00
security	lsm/stable-6.1 PR 20221031	2022-10-31 12:09:42 -07:00
sound	ASoC: Fixes for v6.1	2022-11-23 17:14:10 +01:00
tools	x86:	2022-11-27 09:08:40 -08:00
usr	usr/gen_init_cpio.c: remove unnecessary -1 values from int file	2022-10-03 14:21:44 -07:00
virt	Merge branch 'kvm-dwmw2-fixes' into HEAD	2022-11-23 18:59:45 -05:00
.clang-format	PCI/DOE: Add DOE mailbox support functions	2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	Kbuild: add Rust support	2022-09-28 09:02:20 +02:00
.mailmap	24 hotfixes. 8 marked cc:stable and 16 for post-6.0 issues.	2022-11-25 10:18:25 -08:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: Remove Michal Marek from Kbuild maintainers	2022-11-16 14:53:00 +09:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	s390 updates for 6.1-rc7	2022-11-25 12:37:24 -08:00
Makefile	Linux 6.1-rc7	2022-11-27 13:31:48 -08:00
README

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.