====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.3540/19217 is trying to acquire lock: ffff88806bcca9e0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:885 [inline] ffff88806bcca9e0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: lookup_slow fs/namei.c:1824 [inline] ffff88806bcca9e0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: walk_component+0x345/0x5b0 fs/namei.c:2129 but task is already holding lock: ffffffff90657088 (rpcb_create_local_mutex){+.+.}-{4:4}, at: rpcb_create_local+0x100/0x270 net/sunrpc/rpcb_clnt.c:353 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (rpcb_create_local_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 rpcb_create_local+0x100/0x270 net/sunrpc/rpcb_clnt.c:353 svc_rpcb_setup net/sunrpc/svc.c:425 [inline] svc_bind+0x1e8/0x260 net/sunrpc/svc.c:463 nfsd_create_serv+0x2d2/0x480 fs/nfsd/nfssvc.c:642 nfsd_nl_listener_set_doit+0xdd/0x1b10 fs/nfsd/nfsctl.c:1921 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0xa95/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 __sys_sendmsg+0x16d/0x220 net/socket.c:2700 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #4 (nfsd_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 nfsd_nl_listener_set_doit+0xd5/0x1b10 fs/nfsd/nfsctl.c:1919 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0xa95/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 __sys_sendmsg+0x16d/0x220 net/socket.c:2700 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #3 (cb_lock){++++}-{4:4}: down_read+0x9b/0x480 kernel/locking/rwsem.c:1537 genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] sock_sendmsg+0x3cc/0x470 net/socket.c:752 splice_to_socket+0xaf6/0x1110 fs/splice.c:886 do_splice_from fs/splice.c:938 [inline] do_splice+0x1475/0x1fc0 fs/splice.c:1351 __do_splice+0x32a/0x360 fs/splice.c:1433 __do_sys_splice fs/splice.c:1636 [inline] __se_sys_splice fs/splice.c:1618 [inline] __ia32_sys_splice+0x189/0x250 fs/splice.c:1618 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #2 (&pipe->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 pipe_lock fs/pipe.c:91 [inline] pipe_lock+0x64/0x80 fs/pipe.c:88 iter_file_splice_write+0x1ea/0x12e0 fs/splice.c:683 backing_file_splice_write+0x27f/0x890 fs/backing-file.c:315 ovl_splice_write+0x38d/0x6c0 fs/overlayfs/file.c:440 do_splice_from fs/splice.c:938 [inline] do_splice+0x1475/0x1fc0 fs/splice.c:1351 __do_splice+0x32a/0x360 fs/splice.c:1433 __do_sys_splice fs/splice.c:1636 [inline] __se_sys_splice fs/splice.c:1618 [inline] __ia32_sys_splice+0x189/0x250 fs/splice.c:1618 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (sb_writers#5){.+.+}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1799 [inline] sb_start_write include/linux/fs.h:1935 [inline] mnt_want_write+0x6f/0x450 fs/namespace.c:557 ovl_create_object+0x12c/0x300 fs/overlayfs/dir.c:651 lookup_open.isra.0+0x11d0/0x1580 fs/namei.c:3708 open_last_lookups fs/namei.c:3807 [inline] path_openat+0x893/0x2cb0 fs/namei.c:4043 do_filp_open+0x20b/0x470 fs/namei.c:4073 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_compat_sys_open fs/open.c:1503 [inline] __se_compat_sys_open fs/open.c:1501 [inline] __ia32_compat_sys_open+0x146/0x1e0 fs/open.c:1501 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 down_read+0x9b/0x480 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:885 [inline] lookup_slow fs/namei.c:1824 [inline] walk_component+0x345/0x5b0 fs/namei.c:2129 link_path_walk+0x627/0xe20 fs/namei.c:2497 path_lookupat+0x15a/0x6d0 fs/namei.c:2653 filename_lookup+0x224/0x5f0 fs/namei.c:2683 kern_path+0x35/0x50 fs/namei.c:2816 unix_find_bsd net/unix/af_unix.c:1236 [inline] unix_find_other+0x3d5/0xb50 net/unix/af_unix.c:1298 unix_stream_connect+0x4cb/0x1a20 net/unix/af_unix.c:1699 kernel_connect+0x104/0x180 net/socket.c:3656 xs_local_finish_connecting net/sunrpc/xprtsock.c:2008 [inline] xs_local_setup_socket net/sunrpc/xprtsock.c:2041 [inline] xs_local_connect net/sunrpc/xprtsock.c:2095 [inline] xs_local_connect+0x5f5/0xd60 net/sunrpc/xprtsock.c:2074 xprt_connect+0x7e4/0x9c0 net/sunrpc/xprt.c:948 call_connect net/sunrpc/clnt.c:2160 [inline] call_connect+0x1d9/0x300 net/sunrpc/clnt.c:2137 __rpc_execute+0x382/0x1220 net/sunrpc/sched.c:947 rpc_execute+0x2e8/0x420 net/sunrpc/sched.c:1023 rpc_run_task+0x4a4/0x660 net/sunrpc/clnt.c:1242 rpc_call_null_helper+0x136/0x180 net/sunrpc/clnt.c:2878 rpc_ping net/sunrpc/clnt.c:2895 [inline] rpc_ping+0xb4/0x150 net/sunrpc/clnt.c:2887 rpc_create_xprt+0x387/0x440 net/sunrpc/clnt.c:476 rpc_create+0x469/0x7f0 net/sunrpc/clnt.c:607 rpcb_create_af_local+0x11b/0x310 net/sunrpc/rpcb_clnt.c:258 rpcb_create_local_unix net/sunrpc/rpcb_clnt.c:291 [inline] rpcb_create_local+0x211/0x270 net/sunrpc/rpcb_clnt.c:358 svc_rpcb_setup net/sunrpc/svc.c:425 [inline] svc_bind+0x1e8/0x260 net/sunrpc/svc.c:463 nfsd_create_serv+0x2d2/0x480 fs/nfsd/nfssvc.c:642 nfsd_nl_listener_set_doit+0xdd/0x1b10 fs/nfsd/nfsctl.c:1921 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0xa95/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 __sys_sendmsg+0x16d/0x220 net/socket.c:2700 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth] --> nfsd_mutex --> rpcb_create_local_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rpcb_create_local_mutex); lock(nfsd_mutex); lock(rpcb_create_local_mutex); rlock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 3 locks held by syz.2.3540/19217: #0: ffffffff9042c210 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e9da048 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1b10 fs/nfsd/nfsctl.c:1919 #2: ffffffff90657088 (rpcb_create_local_mutex){+.+.}-{4:4}, at: rpcb_create_local+0x100/0x270 net/sunrpc/rpcb_clnt.c:353 stack backtrace: CPU: 2 UID: 0 PID: 19217 Comm: syz.2.3540 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2043 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 down_read+0x9b/0x480 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:885 [inline] lookup_slow fs/namei.c:1824 [inline] walk_component+0x345/0x5b0 fs/namei.c:2129 link_path_walk+0x627/0xe20 fs/namei.c:2497 path_lookupat+0x15a/0x6d0 fs/namei.c:2653 filename_lookup+0x224/0x5f0 fs/namei.c:2683 kern_path+0x35/0x50 fs/namei.c:2816 unix_find_bsd net/unix/af_unix.c:1236 [inline] unix_find_other+0x3d5/0xb50 net/unix/af_unix.c:1298 unix_stream_connect+0x4cb/0x1a20 net/unix/af_unix.c:1699 kernel_connect+0x104/0x180 net/socket.c:3656 xs_local_finish_connecting net/sunrpc/xprtsock.c:2008 [inline] xs_local_setup_socket net/sunrpc/xprtsock.c:2041 [inline] xs_local_connect net/sunrpc/xprtsock.c:2095 [inline] xs_local_connect+0x5f5/0xd60 net/sunrpc/xprtsock.c:2074 xprt_connect+0x7e4/0x9c0 net/sunrpc/xprt.c:948 call_connect net/sunrpc/clnt.c:2160 [inline] call_connect+0x1d9/0x300 net/sunrpc/clnt.c:2137 __rpc_execute+0x382/0x1220 net/sunrpc/sched.c:947 rpc_execute+0x2e8/0x420 net/sunrpc/sched.c:1023 rpc_run_task+0x4a4/0x660 net/sunrpc/clnt.c:1242 rpc_call_null_helper+0x136/0x180 net/sunrpc/clnt.c:2878 rpc_ping net/sunrpc/clnt.c:2895 [inline] rpc_ping+0xb4/0x150 net/sunrpc/clnt.c:2887 rpc_create_xprt+0x387/0x440 net/sunrpc/clnt.c:476 rpc_create+0x469/0x7f0 net/sunrpc/clnt.c:607 rpcb_create_af_local+0x11b/0x310 net/sunrpc/rpcb_clnt.c:258 rpcb_create_local_unix net/sunrpc/rpcb_clnt.c:291 [inline] rpcb_create_local+0x211/0x270 net/sunrpc/rpcb_clnt.c:358 svc_rpcb_setup net/sunrpc/svc.c:425 [inline] svc_bind+0x1e8/0x260 net/sunrpc/svc.c:463 nfsd_create_serv+0x2d2/0x480 fs/nfsd/nfssvc.c:642 nfsd_nl_listener_set_doit+0xdd/0x1b10 fs/nfsd/nfsctl.c:1921 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg net/socket.c:729 [inline] ____sys_sendmsg+0xa95/0xc70 net/socket.c:2614 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 __sys_sendmsg+0x16d/0x220 net/socket.c:2700 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7f78579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f546655c EFLAGS: 00000296 ORIG_RAX: 0000000000000172 RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000080000040 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi