Hello, syzbot found the following issue on: HEAD commit: 68453767131a ARM: Spectre-BHB: provide empty stub for non-.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17bd4709700000 kernel config: https://syzkaller.appspot.com/x/.config?x=16438642a37fea1 dashboard link: https://syzkaller.appspot.com/bug?extid=6479585dfd4dedd3f7e1 compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6479585dfd4dedd3f7e1@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 5.17.0-rc7-syzkaller-00227-g68453767131a #0 Not tainted ------------------------------------------------------ udevd/6428 is trying to acquire lock: ffff88801d66a938 ((wq_completion)loop3){+.+.}-{0:0}, at: flush_workqueue+0x172/0x16b0 kernel/workqueue.c:2827 but task is already holding lock: ffff88801ab90918 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf8/0x7a0 block/bdev.c:902 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (&disk->open_mutex){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 __mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:600 __mutex_lock kernel/locking/mutex.c:733 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:785 blkdev_get_by_dev+0x169/0xd70 block/bdev.c:804 swsusp_check+0xb0/0x3f0 kernel/power/swap.c:1526 software_resume+0xc8/0x3d0 kernel/power/hibernate.c:979 resume_store+0xdc/0x120 kernel/power/hibernate.c:1181 kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2074 [inline] new_sync_write fs/read_write.c:503 [inline] vfs_write+0xb11/0xe90 fs/read_write.c:590 ksys_write+0x18f/0x2c0 fs/read_write.c:643 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #5 (system_transition_mutex/1){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 __mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:600 __mutex_lock kernel/locking/mutex.c:733 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:785 software_resume+0x7a/0x3d0 kernel/power/hibernate.c:934 resume_store+0xdc/0x120 kernel/power/hibernate.c:1181 kernfs_fop_write_iter+0x3b6/0x510 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2074 [inline] new_sync_write fs/read_write.c:503 [inline] vfs_write+0xb11/0xe90 fs/read_write.c:590 ksys_write+0x18f/0x2c0 fs/read_write.c:643 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #4 (&of->mutex){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 __mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:600 __mutex_lock kernel/locking/mutex.c:733 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:785 kernfs_seq_start+0x50/0x3b0 fs/kernfs/file.c:112 seq_read_iter+0x3cd/0xd30 fs/seq_file.c:225 call_read_iter include/linux/fs.h:2068 [inline] new_sync_read fs/read_write.c:400 [inline] vfs_read+0xaf9/0xe60 fs/read_write.c:481 ksys_read+0x18f/0x2c0 fs/read_write.c:619 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #3 (&p->lock){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 __mutex_lock_common+0x1d5/0x2590 kernel/locking/mutex.c:600 __mutex_lock kernel/locking/mutex.c:733 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:785 seq_read_iter+0xad/0xd30 fs/seq_file.c:182 call_read_iter include/linux/fs.h:2068 [inline] generic_file_splice_read+0x482/0x760 fs/splice.c:311 do_splice_to fs/splice.c:796 [inline] splice_direct_to_actor+0x45f/0xd00 fs/splice.c:870 do_splice_direct+0x291/0x3e0 fs/splice.c:979 do_sendfile+0x6fe/0x1040 fs/read_write.c:1245 __do_sys_sendfile64 fs/read_write.c:1310 [inline] __se_sys_sendfile64+0x171/0x1d0 fs/read_write.c:1296 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #2 (sb_writers#3){.+.+}-{0:0}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1722 [inline] sb_start_write include/linux/fs.h:1792 [inline] file_start_write include/linux/fs.h:2937 [inline] lo_write_bvec drivers/block/loop.c:243 [inline] lo_write_simple drivers/block/loop.c:266 [inline] do_req_filebacked drivers/block/loop.c:495 [inline] loop_handle_cmd drivers/block/loop.c:1852 [inline] loop_process_work+0x167f/0x22b0 drivers/block/loop.c:1892 process_one_work+0x86c/0x1190 kernel/workqueue.c:2307 worker_thread+0xab1/0x1300 kernel/workqueue.c:2454 kthread+0x2a3/0x2d0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 -> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 process_one_work+0x83c/0x1190 kernel/workqueue.c:2283 worker_thread+0xab1/0x1300 kernel/workqueue.c:2454 kthread+0x2a3/0x2d0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 -> #0 ((wq_completion)loop3){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3063 [inline] check_prevs_add kernel/locking/lockdep.c:3186 [inline] validate_chain+0x1dfb/0x8250 kernel/locking/lockdep.c:3801 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 flush_workqueue+0x18e/0x16b0 kernel/workqueue.c:2827 drain_workqueue+0xc3/0x3a0 kernel/workqueue.c:2992 destroy_workqueue+0x7d/0xed0 kernel/workqueue.c:4429 __loop_clr_fd+0x1bd/0x980 drivers/block/loop.c:1124 blkdev_put+0x5a7/0x7a0 blkdev_close+0x58/0x80 block/fops.c:517 __fput+0x3fc/0x870 fs/file_table.c:317 task_work_run+0x146/0x1c0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x209/0x220 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (wq_completion)loop3 --> system_transition_mutex/1 --> &disk->open_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&disk->open_mutex); lock(system_transition_mutex/1); lock(&disk->open_mutex); lock((wq_completion)loop3); *** DEADLOCK *** 1 lock held by udevd/6428: #0: ffff88801ab90918 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf8/0x7a0 block/bdev.c:902 stack backtrace: CPU: 0 PID: 6428 Comm: udevd Not tainted 5.17.0-rc7-syzkaller-00227-g68453767131a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106 check_noncircular+0x2f9/0x3b0 kernel/locking/lockdep.c:2143 check_prev_add kernel/locking/lockdep.c:3063 [inline] check_prevs_add kernel/locking/lockdep.c:3186 [inline] validate_chain+0x1dfb/0x8250 kernel/locking/lockdep.c:3801 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5639 flush_workqueue+0x18e/0x16b0 kernel/workqueue.c:2827 drain_workqueue+0xc3/0x3a0 kernel/workqueue.c:2992 destroy_workqueue+0x7d/0xed0 kernel/workqueue.c:4429 __loop_clr_fd+0x1bd/0x980 drivers/block/loop.c:1124 blkdev_put+0x5a7/0x7a0 blkdev_close+0x58/0x80 block/fops.c:517 __fput+0x3fc/0x870 fs/file_table.c:317 task_work_run+0x146/0x1c0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x209/0x220 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f3819885fc3 Code: 48 ff ff ff b8 ff ff ff ff e9 3e ff ff ff 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 RSP: 002b:00007ffc29e6f138 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007f381972e6a8 RCX: 00007f3819885fc3 RDX: 000000000000001c RSI: 00007ffc29e6e938 RDI: 0000000000000008 RBP: 000055f83c052190 R08: 0000000000000007 R09: 000055f83c057f00 R10: 00007f3819914fc0 R11: 0000000000000246 R12: 0000000000000002 R13: 000055f83c04c1b0 R14: 0000000000000008 R15: 000055f83c028910 </TASK> --- This report is generated by a bot. 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