====================================================== [ INFO: possible circular locking dependency detected ] 4.4.159+ #108 Not tainted ------------------------------------------------------- syz-executor122/2096 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.+.}, at: [] lock_trace+0x44/0xc0 fs/proc/base.c:448 but task is already holding lock: (&p->lock){+.+.+.}, at: [] seq_read+0xdd/0x12b0 fs/seq_file.c:178 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621 [] seq_read+0xdd/0x12b0 fs/seq_file.c:178 [] do_loop_readv_writev+0x148/0x1e0 fs/read_write.c:680 [] do_readv_writev+0x581/0x6f0 fs/read_write.c:810 [] vfs_readv+0x78/0xb0 fs/read_write.c:834 [] kernel_readv fs/splice.c:586 [inline] [] default_file_splice_read+0x50f/0x8f0 fs/splice.c:662 [] do_splice_to+0xf7/0x140 fs/splice.c:1154 [] splice_direct_to_actor+0x242/0x830 fs/splice.c:1226 [] do_splice_direct+0x1a3/0x270 fs/splice.c:1337 [] do_sendfile+0x4e4/0xb80 fs/read_write.c:1227 [] SYSC_sendfile64 fs/read_write.c:1282 [inline] [] SyS_sendfile64+0xc3/0x150 fs/read_write.c:1274 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] percpu_down_read include/linux/percpu-rwsem.h:26 [inline] [] __sb_start_write+0x1ae/0x310 fs/super.c:1221 [] sb_start_write include/linux/fs.h:1515 [inline] [] ext4_run_li_request fs/ext4/super.c:2674 [inline] [] ext4_lazyinit_thread+0x1a7/0x750 fs/ext4/super.c:2773 [] kthread+0x268/0x300 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621 [] ext4_register_li_request+0x304/0x7a0 fs/ext4/super.c:2961 [] ext4_remount+0x1368/0x1bb0 fs/ext4/super.c:4911 [] do_remount_sb2+0x428/0x7d0 fs/super.c:771 [] do_remount fs/namespace.c:2335 [inline] [] do_mount+0x101e/0x2a10 fs/namespace.c:2848 [] SYSC_mount fs/namespace.c:3051 [inline] [] SyS_mount+0x191/0x1c0 fs/namespace.c:3029 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621 [] ext4_register_li_request+0x87/0x7a0 fs/ext4/super.c:2934 [] ext4_remount+0x1368/0x1bb0 fs/ext4/super.c:4911 [] do_remount_sb2+0x428/0x7d0 fs/super.c:771 [] do_remount fs/namespace.c:2335 [inline] [] do_mount+0x101e/0x2a10 fs/namespace.c:2848 [] SYSC_mount fs/namespace.c:3051 [inline] [] SyS_mount+0x191/0x1c0 fs/namespace.c:3029 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] down_read+0x42/0x60 kernel/locking/rwsem.c:22 [] iterate_supers+0xe1/0x260 fs/super.c:537 [] selinux_complete_init+0x2f/0x31 security/selinux/hooks.c:6154 [] security_load_policy+0x886/0x9b0 security/selinux/ss/services.c:2060 [] sel_write_load+0x191/0xfc0 security/selinux/selinuxfs.c:535 [] __vfs_write+0x11c/0x3e0 fs/read_write.c:489 [] vfs_write+0x17e/0x4e0 fs/read_write.c:538 [] SYSC_write fs/read_write.c:585 [inline] [] SyS_write+0xd9/0x1c0 fs/read_write.c:577 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621 [] sel_commit_bools_write+0x87/0x250 security/selinux/selinuxfs.c:1142 [] __vfs_write+0x11c/0x3e0 fs/read_write.c:489 [] __kernel_write+0x10a/0x350 fs/read_write.c:511 [] write_pipe_buf+0x15d/0x1f0 fs/splice.c:1074 [] splice_from_pipe_feed fs/splice.c:776 [inline] [] __splice_from_pipe+0x364/0x790 fs/splice.c:901 [] splice_from_pipe+0xf9/0x170 fs/splice.c:936 [] default_file_splice_write+0x3c/0x80 fs/splice.c:1086 [] do_splice_from fs/splice.c:1128 [inline] [] do_splice fs/splice.c:1404 [inline] [] SYSC_splice fs/splice.c:1707 [inline] [] SyS_splice+0xde1/0x1430 fs/splice.c:1690 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621 [] __pipe_lock fs/pipe.c:86 [inline] [] fifo_open+0x15c/0x9e0 fs/pipe.c:896 [] do_dentry_open+0x38d/0xbd0 fs/open.c:749 [] vfs_open+0x12a/0x210 fs/open.c:862 [] do_last fs/namei.c:3222 [inline] [] path_openat+0x50c/0x39a0 fs/namei.c:3359 [] do_filp_open+0x197/0x270 fs/namei.c:3393 [] do_open_execat+0x10f/0x6f0 fs/exec.c:800 [] do_execveat_common.isra.14+0x6a1/0x1f00 fs/exec.c:1573 [] do_execve fs/exec.c:1679 [inline] [] SYSC_execve fs/exec.c:1760 [inline] [] SyS_execve+0x42/0x50 fs/exec.c:1755 [] return_from_execve+0x0/0x23 [] check_prev_add kernel/locking/lockdep.c:1853 [inline] [] check_prevs_add kernel/locking/lockdep.c:1958 [inline] [] validate_chain kernel/locking/lockdep.c:2144 [inline] [] __lock_acquire+0x3e6c/0x5f10 kernel/locking/lockdep.c:3213 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_killable_nested+0xcc/0xa10 kernel/locking/mutex.c:641 [] lock_trace+0x44/0xc0 fs/proc/base.c:448 [] proc_pid_personality+0x1c/0xc0 fs/proc/base.c:2835 [] proc_single_show+0xfd/0x170 fs/proc/base.c:791 [] seq_read+0x4b6/0x12b0 fs/seq_file.c:240 [] do_loop_readv_writev+0x148/0x1e0 fs/read_write.c:680 [] do_readv_writev+0x581/0x6f0 fs/read_write.c:810 [] vfs_readv+0x78/0xb0 fs/read_write.c:834 [] kernel_readv fs/splice.c:586 [inline] [] default_file_splice_read+0x50f/0x8f0 fs/splice.c:662 [] do_splice_to+0xf7/0x140 fs/splice.c:1154 [] splice_direct_to_actor+0x242/0x830 fs/splice.c:1226 [] do_splice_direct+0x1a3/0x270 fs/splice.c:1337 [] do_sendfile+0x4e4/0xb80 fs/read_write.c:1227 [] SYSC_sendfile64 fs/read_write.c:1282 [inline] [] SyS_sendfile64+0xc3/0x150 fs/read_write.c:1274 [] entry_SYSCALL_64_fastpath+0x1e/0x9a other info that might help us debug this: Chain exists of: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#4); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 1 lock held by syz-executor122/2096: #0: (&p->lock){+.+.+.}, at: [] seq_read+0xdd/0x12b0 fs/seq_file.c:178 stack backtrace: CPU: 1 PID: 2096 Comm: syz-executor122 Not tainted 4.4.159+ #108 0000000000000000 6addc59d46797ecf ffff8800b6666f28 ffffffff81a994bd ffffffff83ab46a0 ffffffff83ab04d0 ffffffff83aaeb80 ffff8801d54467e8 ffff8801d5445f00 ffff8800b6666f70 ffffffff813a84ea 0000000000000001 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [] print_circular_bug.cold.34+0x2f7/0x432 kernel/locking/lockdep.c:1226 [] check_prev_add kernel/locking/lockdep.c:1853 [inline] [] check_prevs_add kernel/locking/lockdep.c:1958 [inline] [] validate_chain kernel/locking/lockdep.c:2144 [inline] [] __lock_acquire+0x3e6c/0x5f10 kernel/locking/lockdep.c:3213 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_killable_nested+0xcc/0xa10 kernel/locking/mutex.c:641 [] lock_trace+0x44/0xc0 fs/proc/base.c:448 [] proc_pid_personality+0x1c/0xc0 fs/proc/base.c:2835 [] proc_single_show+0xfd/0x170 fs/proc/base.c:791 [] seq_read+0x4b6/0x12b0 fs/seq_file.c:240 [] do_loop_readv_writev+0x148/0x1e0 fs/read_write.c:680 [] do_readv_writev+0x581/0x6f0 fs/read_write.c:810 [] vfs_readv+0x78/0xb0 fs/read_write.c:834 [] kernel_readv fs/splice.c:586 [inline] [] default_file_splice_read+0x50f/0x8f0 fs/splice.c:662 [] do_splice_to+0xf7/0x140 fs/splice.c:1154 [] splice_direct_to_actor+0x242/0x830 fs/splice.c:1226 [] do_splice_direct+0x1a3/0x270 fs/splice.c:1337 [] do_sendfile+0x4e4/0xb80 fs/read_write.c:1227 [] SYSC_sendfile64 fs/read_write.c:1282 [inline] [] SyS_sendfile64+0xc3/0x150 fs/read_write.c:1274 [] entry_SYSCALL_64_fastpath+0x1e/0x9a