====================================================== WARNING: possible circular locking dependency detected 5.15.169-syzkaller #0 Not tainted ------------------------------------------------------ syz.0.249/5855 is trying to acquire lock: ffff888076fb5938 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x154/0x1610 kernel/workqueue.c:2830 but task is already holding lock: ffff8881476d5468 (&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:5623 __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+0x2bc/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:3608 [inline] path_openat+0x2705/0x2f20 fs/namei.c:3742 do_filp_open+0x21c/0x460 fs/namei.c:3769 do_sys_openat2+0x13b/0x4f0 fs/open.c:1253 do_sys_open fs/open.c:1269 [inline] __do_sys_openat fs/open.c:1285 [inline] __se_sys_openat fs/open.c:1280 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1280 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #6 (&disk->open_mutex){+.+.}-{3:3}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __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 blkdev_get_by_dev+0x14d/0xa50 block/bdev.c:817 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:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacd/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+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #5 (system_transition_mutex/1){+.+.}-{3:3}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __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:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacd/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+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #4 (&of->mutex){+.+.}-{3:3}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __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:2168 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0xa93/0xe10 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+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #3 (&p->lock){+.+.}-{3:3}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __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 call_read_iter include/linux/fs.h:2168 [inline] generic_file_splice_read+0x4ad/0x790 fs/splice.c:311 do_splice_to fs/splice.c:796 [inline] splice_direct_to_actor+0x448/0xc10 fs/splice.c:870 do_splice_direct+0x285/0x3d0 fs/splice.c:979 do_sendfile+0x622/0x1000 fs/read_write.c:1249 __do_sys_sendfile64 fs/read_write.c:1317 [inline] __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #2 (sb_writers#3){.+.+}-{0:0}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1813 [inline] sb_start_write include/linux/fs.h:1883 [inline] file_start_write include/linux/fs.h:3044 [inline] lo_write_bvec+0x1a3/0x740 drivers/block/loop.c:315 lo_write_simple drivers/block/loop.c:338 [inline] do_req_filebacked drivers/block/loop.c:656 [inline] loop_handle_cmd drivers/block/loop.c:2234 [inline] loop_process_work+0x2309/0x2af0 drivers/block/loop.c:2274 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 process_one_work+0x7f1/0x10c0 kernel/workqueue.c:2286 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #0 ((wq_completion)loop0){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 flush_workqueue+0x170/0x1610 kernel/workqueue.c:2830 drain_workqueue+0xc5/0x390 kernel/workqueue.c:2995 destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4439 __loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1383 blkdev_put_whole block/bdev.c:692 [inline] blkdev_put+0x455/0x790 block/bdev.c:954 swsusp_check+0x201/0x2c0 kernel/power/swap.c:1549 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:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacd/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+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 other info that might help us debug this: Chain exists of: (wq_completion)loop0 --> &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)loop0); *** DEADLOCK *** 7 locks held by syz.0.249/5855: #0: ffff8880231fb4f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2cb/0x380 fs/file.c:1057 #1: ffff88804c472460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x29a/0xe50 fs/read_write.c:590 #2: ffff88801fe57088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x4f0 fs/kernfs/file.c:287 #3: ffff88801bff1830 (kn->active#494){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20b/0x4f0 fs/kernfs/file.c:288 #4: ffffffff8c7d8788 (system_transition_mutex/1){+.+.}-{3:3}, at: software_resume+0x7c/0x3c0 kernel/power/hibernate.c:932 #5: ffff888020ad8518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:912 #6: ffff8881476d5468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1365 stack backtrace: CPU: 1 PID: 5855 Comm: syz.0.249 Not tainted 5.15.169-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 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+0x1649/0x5930 kernel/locking/lockdep.c:3788 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 flush_workqueue+0x170/0x1610 kernel/workqueue.c:2830 drain_workqueue+0xc5/0x390 kernel/workqueue.c:2995 destroy_workqueue+0x7b/0xae0 kernel/workqueue.c:4439 __loop_clr_fd+0x241/0xbe0 drivers/block/loop.c:1383 blkdev_put_whole block/bdev.c:692 [inline] blkdev_put+0x455/0x790 block/bdev.c:954 swsusp_check+0x201/0x2c0 kernel/power/swap.c:1549 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:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacd/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+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f935f874ff9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f935eaf5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f935fa2cf80 RCX: 00007f935f874ff9 RDX: 0000000000000012 RSI: 0000000020000000 RDI: 0000000000000005 RBP: 00007f935f8e7296 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f935fa2cf80 R15: 00007ffccbdacd68 PM: Image not found (code -22)