====================================================== [ INFO: possible circular locking dependency detected ] 4.4.171+ #12 Not tainted ------------------------------------------------------- syz-executor3/4921 is trying to acquire lock: (sel_mutex){+.+.+.}, at: [] sel_commit_bools_write+0x89/0x260 security/selinux/selinuxfs.c:1142 but task is already holding lock: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock_nested fs/pipe.c:65 [inline] (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x63/0x80 fs/pipe.c:73 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+0xc1/0xb80 kernel/locking/mutex.c:621 [] pipe_lock_nested fs/pipe.c:65 [inline] [] pipe_lock+0x63/0x80 fs/pipe.c:73 [] iter_file_splice_write+0x179/0xb30 fs/splice.c:974 [] do_splice_from fs/splice.c:1128 [inline] [] do_splice fs/splice.c:1404 [inline] [] SYSC_splice fs/splice.c:1707 [inline] [] SyS_splice+0xd71/0x13a0 fs/splice.c:1690 [] 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+0x1af/0x310 fs/super.c:1221 [] sb_start_write include/linux/fs.h:1517 [inline] [] ext4_run_li_request fs/ext4/super.c:2685 [inline] [] ext4_lazyinit_thread fs/ext4/super.c:2784 [inline] [] ext4_lazyinit_thread+0x1e4/0x7b0 fs/ext4/super.c:2760 [] kthread+0x273/0x310 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] ext4_register_li_request+0x2fd/0x7d0 fs/ext4/super.c:2972 [] ext4_remount+0x1366/0x1b90 fs/ext4/super.c:4922 [] do_remount_sb2+0x41b/0x7a0 fs/super.c:771 [] do_remount fs/namespace.c:2347 [inline] [] do_mount+0xfdb/0x2a40 fs/namespace.c:2860 [] SYSC_mount fs/namespace.c:3063 [inline] [] SyS_mount+0x130/0x1d0 fs/namespace.c:3041 [] 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+0xc1/0xb80 kernel/locking/mutex.c:621 [] ext4_register_li_request+0x89/0x7d0 fs/ext4/super.c:2945 [] ext4_remount+0x1366/0x1b90 fs/ext4/super.c:4922 [] do_remount_sb2+0x41b/0x7a0 fs/super.c:771 [] do_remount fs/namespace.c:2347 [inline] [] do_mount+0xfdb/0x2a40 fs/namespace.c:2860 [] SYSC_mount fs/namespace.c:3063 [inline] [] SyS_mount+0x130/0x1d0 fs/namespace.c:3041 [] 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+0xe1/0x250 fs/super.c:537 [] selinux_complete_init+0x2f/0x31 security/selinux/hooks.c:6154 [] security_load_policy+0x69d/0x9c0 security/selinux/ss/services.c:2060 [] sel_write_load+0x175/0xf90 security/selinux/selinuxfs.c:535 [] __vfs_write+0x116/0x3d0 fs/read_write.c:489 [] vfs_write+0x182/0x4e0 fs/read_write.c:538 [] SYSC_write fs/read_write.c:585 [inline] [] SyS_write+0xdc/0x1c0 fs/read_write.c:577 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] 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+0x37d6/0x4f50 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_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] sel_commit_bools_write+0x89/0x260 security/selinux/selinuxfs.c:1142 [] __vfs_write+0x116/0x3d0 fs/read_write.c:489 [] __kernel_write+0x112/0x370 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+0x37e/0x7a0 fs/splice.c:901 [] splice_from_pipe+0x108/0x170 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+0xd71/0x13a0 fs/splice.c:1690 [] entry_SYSCALL_64_fastpath+0x1e/0x9a other info that might help us debug this: Chain exists of: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex/1); lock(sb_writers#4); lock(&pipe->mutex/1); lock(sel_mutex); *** DEADLOCK *** 2 locks held by syz-executor3/4921: #0: (sb_writers#3){.+.+.+}, at: [] file_start_write include/linux/fs.h:2543 [inline] #0: (sb_writers#3){.+.+.+}, at: [] do_splice fs/splice.c:1403 [inline] #0: (sb_writers#3){.+.+.+}, at: [] SYSC_splice fs/splice.c:1707 [inline] #0: (sb_writers#3){.+.+.+}, at: [] SyS_splice+0xf2d/0x13a0 fs/splice.c:1690 #1: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock_nested fs/pipe.c:65 [inline] #1: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x63/0x80 fs/pipe.c:73 stack backtrace: CPU: 0 PID: 4921 Comm: syz-executor3 Not tainted 4.4.171+ #12 0000000000000000 5fb9a5d086bbc00e ffff8801d87a75c0 ffffffff81aacd31 ffffffff84057a80 ffff8800ba1e8000 ffffffff83ab8870 ffffffff83abd460 ffffffff83abc1d0 ffff8801d87a7610 ffffffff813abad4 ffffffff83e26880 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] print_circular_bug.cold+0x2f7/0x44e 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+0x37d6/0x4f50 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_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] sel_commit_bools_write+0x89/0x260 security/selinux/selinuxfs.c:1142 [] __vfs_write+0x116/0x3d0 fs/read_write.c:489 [] __kernel_write+0x112/0x370 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+0x37e/0x7a0 fs/splice.c:901 [] splice_from_pipe+0x108/0x170 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+0xd71/0x13a0 fs/splice.c:1690 [] entry_SYSCALL_64_fastpath+0x1e/0x9a