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possible deadlock in btrfs_run_dev_stats

Status: upstream: reported C repro on 2024/05/02 02:20
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+ee7f25e27b96da12819f@syzkaller.appspotmail.com
First crash: 404d, last: 14d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2024/05/04 upstream (ToT) 7367539ad4b0 C [report] BUG: MAX_LOCKDEP_KEYS too low!
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 possible deadlock in btrfs_run_dev_stats btrfs 4 828d 923d 0/1 upstream: reported on 2022/11/29 20:35
▶ ▼ Last patch testing requests (9)
Created Duration User Patch Repo Result
2025/05/27 06:33 15m retest repro linux-5.15.y report log
2025/05/27 06:33 15m retest repro linux-5.15.y report log
2025/05/27 06:33 15m retest repro linux-5.15.y report log
2025/05/27 06:33 18m retest repro linux-5.15.y report log
2025/05/27 06:33 11m retest repro linux-5.15.y report log
2025/03/31 02:42 11m retest repro linux-5.15.y report log
2025/03/31 02:42 11m retest repro linux-5.15.y report log
2025/03/31 02:42 12m retest repro linux-5.15.y report log
2025/03/31 02:42 12m retest repro linux-5.15.y report log

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.182-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor314/4022 is trying to acquire lock:
ffff0000d83930e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_run_dev_stats+0xe0/0xcac fs/btrfs/volumes.c:7985

but task is already holding lock:
ffff0000cdd90720 (&fs_info->tree_log_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xe44/0x3044 fs/btrfs/transaction.c:2369

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&fs_info->tree_log_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
       btrfs_commit_transaction+0xe44/0x3044 fs/btrfs/transaction.c:2369
       btrfs_sync_fs+0x628/0xb2c fs/btrfs/super.c:1454
       sync_filesystem+0x1a0/0x218 fs/sync.c:66
       generic_shutdown_super+0x70/0x2f0 fs/super.c:448
       kill_anon_super+0x4c/0x80 fs/super.c:1089
       btrfs_kill_super+0x40/0x58 fs/btrfs/super.c:2390
       deactivate_locked_super+0xb8/0x13c fs/super.c:335
       deactivate_super+0xf8/0x118 fs/super.c:366
       cleanup_mnt+0x3a4/0x458 fs/namespace.c:1143
       __cleanup_mnt+0x20/0x30 fs/namespace.c:1150
       task_work_run+0x12c/0x1e0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       do_notify_resume+0x24b4/0x3128 arch/arm64/kernel/signal.c:949
       prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
       el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #3 (&fs_info->reloc_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
       btrfs_record_root_in_trans fs/btrfs/transaction.c:513 [inline]
       start_transaction+0x440/0x13f0 fs/btrfs/transaction.c:750
       btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:793
       btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436
       btrfs_update_time+0x224/0x248 fs/btrfs/inode.c:6478
       inode_update_time fs/inode.c:1893 [inline]
       touch_atime+0x3d0/0x914 fs/inode.c:1966
       file_accessed include/linux/fs.h:2521 [inline]
       iterate_dir+0x280/0x4cc fs/readdir.c:70
       __do_sys_getdents64 fs/readdir.c:369 [inline]
       __se_sys_getdents64 fs/readdir.c:354 [inline]
       __arm64_sys_getdents64+0x11c/0x340 fs/readdir.c:354
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #2 (sb_internal#2){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1811 [inline]
       sb_start_intwrite include/linux/fs.h:1928 [inline]
       start_transaction+0x624/0x13f0 fs/btrfs/transaction.c:680
       btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:793
       btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436
       btrfs_update_time+0x224/0x248 fs/btrfs/inode.c:6478
       inode_update_time fs/inode.c:1893 [inline]
       touch_atime+0x3d0/0x914 fs/inode.c:1966
       file_accessed include/linux/fs.h:2521 [inline]
       iterate_dir+0x280/0x4cc fs/readdir.c:70
       __do_sys_getdents64 fs/readdir.c:369 [inline]
       __se_sys_getdents64 fs/readdir.c:354 [inline]
       __arm64_sys_getdents64+0x11c/0x340 fs/readdir.c:354
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&type->i_mutex_dir_key#6){++++}-{3:3}:
       down_read+0xc0/0x390 kernel/locking/rwsem.c:1498
       inode_lock_shared include/linux/fs.h:797 [inline]
       lookup_slow+0x4c/0x80 fs/namei.c:1679
       walk_component+0x2b0/0x3a8 fs/namei.c:1976
       lookup_last fs/namei.c:2431 [inline]
       path_lookupat+0x13c/0x3d0 fs/namei.c:2455
       filename_lookup+0x180/0x414 fs/namei.c:2484
       kern_path+0x4c/0x190 fs/namei.c:2582
       lookup_bdev+0xbc/0x244 block/bdev.c:982
       device_matched fs/btrfs/volumes.c:568 [inline]
       btrfs_free_stale_devices+0x614/0x908 fs/btrfs/volumes.c:608
       btrfs_forget_devices+0x5c/0x98 fs/btrfs/volumes.c:1431
       btrfs_control_ioctl+0x130/0x248 fs/btrfs/super.c:2450
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&fs_devs->device_list_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012
       lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
       btrfs_run_dev_stats+0xe0/0xcac fs/btrfs/volumes.c:7985
       commit_cowonly_roots+0x144/0x7e8 fs/btrfs/transaction.c:1292
       btrfs_commit_transaction+0xf04/0x3044 fs/btrfs/transaction.c:2394
       btrfs_sync_fs+0x628/0xb2c fs/btrfs/super.c:1454
       sync_filesystem+0x1a0/0x218 fs/sync.c:66
       generic_shutdown_super+0x70/0x2f0 fs/super.c:448
       kill_anon_super+0x4c/0x80 fs/super.c:1089
       btrfs_kill_super+0x40/0x58 fs/btrfs/super.c:2390
       deactivate_locked_super+0xb8/0x13c fs/super.c:335
       deactivate_super+0xf8/0x118 fs/super.c:366
       cleanup_mnt+0x3a4/0x458 fs/namespace.c:1143
       __cleanup_mnt+0x20/0x30 fs/namespace.c:1150
       task_work_run+0x12c/0x1e0 kernel/task_work.c:188
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       do_notify_resume+0x24b4/0x3128 arch/arm64/kernel/signal.c:949
       prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
       el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
  &fs_devs->device_list_mutex --> &fs_info->reloc_mutex --> &fs_info->tree_log_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&fs_info->tree_log_mutex);
                               lock(&fs_info->reloc_mutex);
                               lock(&fs_info->tree_log_mutex);
  lock(&fs_devs->device_list_mutex);

 *** DEADLOCK ***

3 locks held by syz-executor314/4022:
 #0: ffff0000c1a680e0 (&type->s_umount_key#41){+.+.}-{3:3}, at: deactivate_super+0xf0/0x118 fs/super.c:365
 #1: ffff0000cdd90c90 (&fs_info->reloc_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xda8/0x3044 fs/btrfs/transaction.c:2319
 #2: ffff0000cdd90720 (&fs_info->tree_log_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xe44/0x3044 fs/btrfs/transaction.c:2369

stack backtrace:
CPU: 0 PID: 4022 Comm: syz-executor314 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011
 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012
 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
 btrfs_run_dev_stats+0xe0/0xcac fs/btrfs/volumes.c:7985
 commit_cowonly_roots+0x144/0x7e8 fs/btrfs/transaction.c:1292
 btrfs_commit_transaction+0xf04/0x3044 fs/btrfs/transaction.c:2394
 btrfs_sync_fs+0x628/0xb2c fs/btrfs/super.c:1454
 sync_filesystem+0x1a0/0x218 fs/sync.c:66
 generic_shutdown_super+0x70/0x2f0 fs/super.c:448
 kill_anon_super+0x4c/0x80 fs/super.c:1089
 btrfs_kill_super+0x40/0x58 fs/btrfs/super.c:2390
 deactivate_locked_super+0xb8/0x13c fs/super.c:335
 deactivate_super+0xf8/0x118 fs/super.c:366
 cleanup_mnt+0x3a4/0x458 fs/namespace.c:1143
 __cleanup_mnt+0x20/0x30 fs/namespace.c:1150
 task_work_run+0x12c/0x1e0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 do_notify_resume+0x24b4/0x3128 arch/arm64/kernel/signal.c:949
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
 el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/11 17:31 linux-5.15.y 3b8db0e4f263 77908e5f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/09/21 06:32 linux-5.15.y 3a5928702e71 6f888b75 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/08/24 07:07 linux-5.15.y fa93fa65db6e d7d32352 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/07/25 07:38 linux-5.15.y 7c6d66f0266f d1a1b0ca .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/07/25 05:32 linux-5.15.y 7c6d66f0266f d1a1b0ca .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/07/25 03:31 linux-5.15.y 7c6d66f0266f d1a1b0ca .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/07/25 01:30 linux-5.15.y 7c6d66f0266f d1a1b0ca .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/07/20 06:04 linux-5.15.y 7c6d66f0266f 890ce4f3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/05/02 03:54 linux-5.15.y b925f60c6ee7 3ba885bc .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/05/02 03:16 linux-5.15.y b925f60c6ee7 3ba885bc .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/06/23 19:49 linux-5.15.y 4878aadf2d15 edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in btrfs_run_dev_stats
2025/03/16 19:15 linux-5.15.y 0c935c049b5c e2826670 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/05/02 02:22 linux-5.15.y b925f60c6ee7 3ba885bc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
2024/05/02 02:20 linux-5.15.y b925f60c6ee7 3ba885bc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in btrfs_run_dev_stats
* Struck through repros no longer work on HEAD.