====================================================== WARNING: possible circular locking dependency detected 5.0.0 #4 Not tainted ------------------------------------------------------ syz-executor.5/20318 is trying to acquire lock: 000000006d8db365 (&sig->cred_guard_mutex){+.+.}, at: do_io_accounting+0x1f4/0x830 fs/proc/base.c:2707 but task is already holding lock: 0000000092dae05e (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: kobject: 'loop4' (00000000256e4625): kobject_uevent_env -> #2 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x71/0x1130 fs/seq_file.c:161 proc_reg_read+0x1fa/0x2c0 fs/proc/inode.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0xf0/0x160 fs/read_write.c:983 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:417 kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' do_splice_to+0x12a/0x190 fs/splice.c:880 do_splice+0xf7c/0x1330 fs/splice.c:1178 __do_sys_splice fs/splice.c:1419 [inline] __se_sys_splice fs/splice.c:1399 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1399 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&pipe->mutex/1){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __pipe_lock fs/pipe.c:83 [inline] fifo_open+0x159/0xb00 fs/pipe.c:905 do_dentry_open+0x47d/0x1130 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x10d7/0x4690 fs/namei.c:3534 do_filp_open+0x1a1/0x280 fs/namei.c:3564 do_open_execat+0x13b/0x6d0 fs/exec.c:856 __do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758 do_execveat_common fs/exec.c:1865 [inline] do_execve fs/exec.c:1882 [inline] __do_sys_execve fs/exec.c:1963 [inline] __se_sys_execve fs/exec.c:1958 [inline] __x64_sys_execve+0x8f/0xc0 fs/exec.c:1958 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3841 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 do_io_accounting+0x1f4/0x830 fs/proc/base.c:2707 proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2756 proc_single_show+0xf6/0x180 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0xf0/0x160 fs/read_write.c:983 do_readv+0xf6/0x290 fs/read_write.c:1016 __do_sys_readv fs/read_write.c:1103 [inline] __se_sys_readv fs/read_write.c:1100 [inline] __x64_sys_readv+0x75/0xb0 fs/read_write.c:1100 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> &pipe->mutex/1 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(&pipe->mutex/1); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor.5/20318: #0: 000000008d402db1 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:795 #1: 0000000092dae05e (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161 stack backtrace: CPU: 0 PID: 20318 Comm: syz-executor.5 Not tainted 5.0.0 #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1224 check_prev_add kernel/locking/lockdep.c:1866 [inline] check_prevs_add kernel/locking/lockdep.c:1979 [inline] validate_chain kernel/locking/lockdep.c:2350 [inline] __lock_acquire+0x2f00/0x4700 kernel/locking/lockdep.c:3338 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3841 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 do_io_accounting+0x1f4/0x830 fs/proc/base.c:2707 proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2756 proc_single_show+0xf6/0x180 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0xf0/0x160 fs/read_write.c:983 do_readv+0xf6/0x290 fs/read_write.c:1016 __do_sys_readv fs/read_write.c:1103 [inline] __se_sys_readv fs/read_write.c:1100 [inline] __x64_sys_readv+0x75/0xb0 fs/read_write.c:1100 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457e29 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f4f0183cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000013 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457e29 RDX: 0000000000000001 RSI: 0000000020000300 RDI: 0000000000000003 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4f0183d6d4 R13: 00000000004c494f R14: 00000000004d8510 R15: 00000000ffffffff kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (000000003c279170): kobject_uevent_env kobject: 'loop5' (000000003c279170): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000086d67a7d): kobject_uevent_env kobject: 'loop0' (0000000086d67a7d): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000256e4625): kobject_uevent_env kobject: 'loop4' (00000000256e4625): fill_kobj_path: path = '/devices/virtual/block/loop4'