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possible deadlock in __loop_clr_fd

Status: upstream: reported on 2023/03/09 14:25
Reported-by: syzbot+a94f42fb4f5d3739ef4a@syzkaller.appspotmail.com
First crash: 79d, last: 1d12h
▶ ▼ Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in __loop_clr_fd (2) block ext4 C unreliable 6977 564d 689d 22/24 fixed on 2021/11/10 00:50
upstream possible deadlock in __loop_clr_fd 2 799d 796d 0/24 auto-closed as invalid on 2021/05/18 10:52
upstream possible deadlock in __loop_clr_fd (3) block 2972 500d 563d 22/24 fixed on 2022/03/08 16:11

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
5.15.113-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/28541 is trying to acquire lock:
ffff888019cda138 ((wq_completion)loop5){+.+.}-{0:0}, at: flush_workqueue+0x154/0x1610 kernel/workqueue.c:2827

but task is already holding lock:
ffff88801af60468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1365

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #7 (&lo->lo_mutex){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_killable_nested+0x17/0x20 kernel/locking/mutex.c:758
       lo_open+0x68/0x100 drivers/block/loop.c:2055
       blkdev_get_whole+0x94/0x390 block/bdev.c:669
       blkdev_get_by_dev+0x2b2/0xa50 block/bdev.c:824
       blkdev_open+0x138/0x2d0 block/fops.c:463
       do_dentry_open+0x807/0xfb0 fs/open.c:826
       do_open fs/namei.c:3538 [inline]
       path_openat+0x2702/0x2f20 fs/namei.c:3672
       do_filp_open+0x21c/0x460 fs/namei.c:3699
       do_sys_openat2+0x13b/0x500 fs/open.c:1211
       do_sys_open fs/open.c:1227 [inline]
       __do_sys_openat fs/open.c:1243 [inline]
       __se_sys_openat fs/open.c:1238 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1238
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #6 (&disk->open_mutex){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       bd_register_pending_holders+0x33/0x320 block/holder.c:161
       device_add_disk+0x526/0xc50 block/genhd.c:484
       add_disk include/linux/genhd.h:212 [inline]
       loop_add+0x5f2/0x880 drivers/block/loop.c:2430
       blk_request_module+0x181/0x1a0 block/genhd.c:684
       blkdev_get_no_open+0x39/0x190 block/bdev.c:740
       blkdev_get_by_dev+0x89/0xa50 block/bdev.c:804
       blkdev_open+0x138/0x2d0 block/fops.c:463
       do_dentry_open+0x807/0xfb0 fs/open.c:826
       do_open fs/namei.c:3538 [inline]
       path_openat+0x2702/0x2f20 fs/namei.c:3672
       do_filp_open+0x21c/0x460 fs/namei.c:3699
       do_sys_openat2+0x13b/0x500 fs/open.c:1211
       do_sys_open fs/open.c:1227 [inline]
       __do_sys_creat fs/open.c:1301 [inline]
       __se_sys_creat fs/open.c:1295 [inline]
       __x64_sys_creat+0x11f/0x160 fs/open.c:1295
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #5 (major_names_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       blk_request_module+0x2f/0x1a0 block/genhd.c:681
       blkdev_get_no_open+0x39/0x190 block/bdev.c:740
       blkdev_get_by_dev+0x89/0xa50 block/bdev.c:804
       swsusp_check+0xb1/0x2c0 kernel/power/swap.c:1526
       software_resume+0xc6/0x3c0 kernel/power/hibernate.c:977
       resume_store+0xe3/0x130 kernel/power/hibernate.c:1179
       kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2103 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0xacf/0xe50 fs/read_write.c:594
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #4 (system_transition_mutex/1){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       software_resume+0x7c/0x3c0 kernel/power/hibernate.c:932
       resume_store+0xe3/0x130 kernel/power/hibernate.c:1179
       kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2103 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0xacf/0xe50 fs/read_write.c:594
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #3 (&of->mutex){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       kernfs_seq_start+0x50/0x3b0 fs/kernfs/file.c:112
       seq_read_iter+0x3d0/0xd10 fs/seq_file.c:225
       call_read_iter include/linux/fs.h:2097 [inline]
       new_sync_read fs/read_write.c:404 [inline]
       vfs_read+0xa9f/0xe10 fs/read_write.c:485
       ksys_read+0x1a2/0x2c0 fs/read_write.c:623
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #2 (&p->lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       seq_read_iter+0xae/0xd10 fs/seq_file.c:182
       do_iter_readv_writev+0x594/0x7a0
       do_iter_read+0x1ec/0x760 fs/read_write.c:790
       lo_read_simple drivers/block/loop.c:392 [inline]
       do_req_filebacked drivers/block/loop.c:663 [inline]
       loop_handle_cmd drivers/block/loop.c:2234 [inline]
       loop_process_work+0x1d18/0x2af0 drivers/block/loop.c:2274
       process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2307
       worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
       kthread+0x3f6/0x4f0 kernel/kthread.c:319
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #1 ((work_completion)(&worker->work)){+.+.}-{0:0}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       process_one_work+0x7f1/0x10c0 kernel/workqueue.c:2283
       worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
       kthread+0x3f6/0x4f0 kernel/kthread.c:319
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #0 ((wq_completion)loop5){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1646/0x58b0 kernel/locking/lockdep.c:3787
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
       flush_workqueue+0x170/0x1610 kernel/workqueue.c:2827
       drain_workqueue+0xc5/0x390 kernel/workqueue.c:2992
       destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4427
       __loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1383
       loop_clr_fd drivers/block/loop.c:1509 [inline]
       lo_ioctl+0x1529/0x23b0 drivers/block/loop.c:1865
       blkdev_ioctl+0x333/0x6b0 block/ioctl.c:601
       block_ioctl+0xb1/0xf0 block/fops.c:493
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x61/0xcb

other info that might help us debug this:

Chain exists of:
  (wq_completion)loop5 --> &disk->open_mutex --> &lo->lo_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&lo->lo_mutex);
                               lock(&disk->open_mutex);
                               lock(&lo->lo_mutex);
  lock((wq_completion)loop5);

 *** DEADLOCK ***

1 lock held by syz-executor.5/28541:
 #0: ffff88801af60468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1365

stack backtrace:
CPU: 1 PID: 28541 Comm: syz-executor.5 Not tainted 5.15.113-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 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+0x1646/0x58b0 kernel/locking/lockdep.c:3787
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
 flush_workqueue+0x170/0x1610 kernel/workqueue.c:2827
 drain_workqueue+0xc5/0x390 kernel/workqueue.c:2992
 destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4427
 __loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1383
 loop_clr_fd drivers/block/loop.c:1509 [inline]
 lo_ioctl+0x1529/0x23b0 drivers/block/loop.c:1865
 blkdev_ioctl+0x333/0x6b0 block/ioctl.c:601
 block_ioctl+0xb1/0xf0 block/fops.c:493
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fa3b2351f57
Code: 3c 1c 48 f7 d8 49 39 c4 72 b8 e8 c4 57 02 00 85 c0 78 bd 48 83 c4 08 4c 89 e0 5b 41 5c c3 0f 1f 44 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc07caa58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffcc07caae0 RCX: 00007fa3b2351f57
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 00007ffcc07ca8f0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000032
R13: 0000000000242adb R14: 0000000000000019 R15: 00007ffcc07cab20
 </TASK>

Crashes (41):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Manager Title
2023/05/26 21:23 linux-5.15.y 1fe619a7d252 cf184559 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/16 22:03 linux-5.15.y b0ece631f84a 11c89444 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/16 12:00 linux-5.15.y b0ece631f84a 71b00cfb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/15 18:45 linux-5.15.y b0ece631f84a c4d362e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/15 12:31 linux-5.15.y b0ece631f84a c4d362e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/13 01:49 linux-5.15.y b0ece631f84a ecca8a24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/13 01:42 linux-5.15.y b0ece631f84a ecca8a24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/11 12:14 linux-5.15.y 8a7f2a5c5aa1 0fbd49f4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/06 02:15 linux-5.15.y 8a7f2a5c5aa1 de870ca5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/05 19:36 linux-5.15.y 8a7f2a5c5aa1 de870ca5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/04 20:40 linux-5.15.y 8a7f2a5c5aa1 518a39a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/04 11:44 linux-5.15.y 8a7f2a5c5aa1 3a560463 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/04 02:42 linux-5.15.y 8a7f2a5c5aa1 b5918830 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/03 20:48 linux-5.15.y 8a7f2a5c5aa1 b5918830 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/03 08:33 linux-5.15.y 8a7f2a5c5aa1 48e0a81d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/03 05:53 linux-5.15.y 8a7f2a5c5aa1 48e0a81d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/01 20:02 linux-5.15.y 8a7f2a5c5aa1 62df2017 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/01 14:11 linux-5.15.y 8a7f2a5c5aa1 62df2017 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/04/28 21:49 linux-5.15.y f48aeeaaa64c 62df2017 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/04/24 21:20 linux-5.15.y 3299fb36854f fdc18293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/04/12 17:38 linux-5.15.y d86dfc4d95cd 1a1596b6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/04/06 15:45 linux-5.15.y d86dfc4d95cd 08707520 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/04/05 22:21 linux-5.15.y d86dfc4d95cd 8b834965 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/03/31 12:06 linux-5.15.y c957cbb87315 f325deb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/03/23 03:10 linux-5.15.y 115472395b0a f94b4a29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/03/22 03:34 linux-5.15.y 8020ae3c051d 8b4eb097 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/03/20 15:12 linux-5.15.y 8020ae3c051d 7939252e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/03/17 13:48 linux-5.15.y 8020ae3c051d 18b58603 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/03/09 14:24 linux-5.15.y d9b4a0c83a2d f08b59ac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __loop_clr_fd
2023/05/25 03:15 linux-5.15.y 1fe619a7d252 4bce1a3e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/05/12 18:46 linux-5.15.y b0ece631f84a ecca8a24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/05/04 18:35 linux-5.15.y 8a7f2a5c5aa1 518a39a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/05/01 09:42 linux-5.15.y 8a7f2a5c5aa1 62df2017 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/29 06:09 linux-5.15.y f48aeeaaa64c 62df2017 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/28 14:01 linux-5.15.y f48aeeaaa64c 70a605de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/28 03:28 linux-5.15.y f48aeeaaa64c 6f3d6fa7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/25 15:32 linux-5.15.y 3299fb36854f 65320f8e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/24 01:56 linux-5.15.y 3299fb36854f 2b32bd34 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/19 03:35 linux-5.15.y 4fdad925aa1a d931e9f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/04/01 14:28 linux-5.15.y c957cbb87315 f325deb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
2023/03/24 22:46 linux-5.15.y 115472395b0a 9700afae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 possible deadlock in __loop_clr_fd
* Struck through repros no longer work on HEAD.