====================================================== WARNING: possible circular locking dependency detected 5.0.0-rc4+ #49 Not tainted ------------------------------------------------------ syz-executor5/26571 is trying to acquire lock: 00000000c872257e (&sig->cred_guard_mutex){+.+.}, at: do_io_accounting+0x1d1/0xfe0 fs/proc/base.c:2711 but task is already holding lock: 00000000ef1151fa (&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: -> #2 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x12f/0x1670 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x71/0x1130 fs/seq_file.c:161 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+0x175/0x1c0 fs/read_write.c:983 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x50c/0xac0 fs/splice.c:417 do_splice_to+0x12a/0x190 fs/splice.c:880 do_splice+0xff7/0x1410 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+0x1a3/0x800 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+0x12f/0x1670 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+0x48a/0x1210 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x144f/0x5650 fs/namei.c:3534 do_filp_open+0x26f/0x370 fs/namei.c:3564 do_open_execat+0x20e/0x930 fs/exec.c:856 __do_execve_file.isra.0+0x1966/0x2700 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+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x12f/0x1670 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 do_io_accounting+0x1d1/0xfe0 fs/proc/base.c:2711 proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2760 proc_single_show+0xf6/0x180 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 __vfs_read+0x116/0xb20 fs/read_write.c:416 vfs_read+0x194/0x3e0 fs/read_write.c:452 ksys_pread64+0x183/0x1c0 fs/read_write.c:626 __do_sys_pread64 fs/read_write.c:636 [inline] __se_sys_pread64 fs/read_write.c:633 [inline] __x64_sys_pread64+0x97/0xf0 fs/read_write.c:633 do_syscall_64+0x1a3/0x800 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 *** 1 lock held by syz-executor5/26571: #0: 00000000ef1151fa (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161 stack backtrace: CPU: 0 PID: 26571 Comm: syz-executor5 Not tainted 5.0.0-rc4+ #49 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+0x1db/0x2d0 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+0x3014/0x4a30 kernel/locking/lockdep.c:3338 lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x12f/0x1670 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 do_io_accounting+0x1d1/0xfe0 fs/proc/base.c:2711 proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2760 proc_single_show+0xf6/0x180 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 __vfs_read+0x116/0xb20 fs/read_write.c:416 vfs_read+0x194/0x3e0 fs/read_write.c:452 ksys_pread64+0x183/0x1c0 fs/read_write.c:626 __do_sys_pread64 fs/read_write.c:636 [inline] __se_sys_pread64 fs/read_write.c:633 [inline] __x64_sys_pread64+0x97/0xf0 fs/read_write.c:633 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458089 Code: 6d b7 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f5266625c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000011 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458089 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f52666266d4 R13: 00000000004c4b3f R14: 00000000004d82a8 R15: 00000000ffffffff kobject: 'loop2' (000000009daeb684): kobject_uevent_env kobject: 'loop2' (000000009daeb684): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop2' (000000009daeb684): kobject_uevent_env kobject: 'loop2' (000000009daeb684): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'loop3' (000000004ac45bd4): kobject_uevent_env kobject: 'loop3' (000000004ac45bd4): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'loop4' (000000004c7c6c36): kobject_uevent_env kobject: 'loop4' (000000004c7c6c36): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop2' (000000009daeb684): kobject_uevent_env kobject: 'loop2' (000000009daeb684): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'loop4' (000000004c7c6c36): kobject_uevent_env kobject: 'loop4' (000000004c7c6c36): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (00000000984454f0): kobject_uevent_env kobject: 'loop5' (00000000984454f0): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop3' (000000004ac45bd4): kobject_uevent_env kobject: 'loop3' (000000004ac45bd4): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop3' (000000004ac45bd4): kobject_uevent_env kobject: 'loop3' (000000004ac45bd4): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop2' (000000009daeb684): kobject_uevent_env kobject: 'loop2' (000000009daeb684): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'loop3' (000000004ac45bd4): kobject_uevent_env kobject: 'loop3' (000000004ac45bd4): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'loop4' (000000004c7c6c36): kobject_uevent_env kobject: 'loop4' (000000004c7c6c36): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (00000000984454f0): kobject_uevent_env kobject: 'loop5' (00000000984454f0): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop3' (000000004ac45bd4): kobject_uevent_env kobject: 'loop3' (000000004ac45bd4): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop2' (000000009daeb684): kobject_uevent_env kobject: 'loop2' (000000009daeb684): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'loop4' (000000004c7c6c36): kobject_uevent_env kobject: 'loop4' (000000004c7c6c36): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop5' (00000000984454f0): kobject_uevent_env kobject: 'loop5' (00000000984454f0): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (0000000025cf162f): kobject_uevent_env kobject: 'loop0' (0000000025cf162f): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop3' (000000004ac45bd4): kobject_uevent_env kobject: 'loop3' (000000004ac45bd4): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'loop1' (00000000294f5669): kobject_uevent_env kobject: 'loop1' (00000000294f5669): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop4' (000000004c7c6c36): kobject_uevent_env kobject: 'loop4' (000000004c7c6c36): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop2' (000000009daeb684): kobject_uevent_env kobject: 'loop2' (000000009daeb684): fill_kobj_path: path = '/devices/virtual/block/loop2'