RBP: 00007f61bf3b8a90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b767a R13: 00007f61bf3b8bc8 R14: 00000000004b767a R15: 0000000000000000 ============================================ WARNING: possible recursive locking detected 4.15.0-rc6+ #250 Not tainted -------------------------------------------- syz-executor6/27866 is trying to acquire lock: (&pn->all_ppp_mutex){+.+.}, at: [<0000000005a8dd59>] ppp_dev_uninit+0x23a/0x440 drivers/net/ppp/ppp_generic.c:1369 but task is already holding lock: (&pn->all_ppp_mutex){+.+.}, at: [<00000000873fdeba>] ppp_unit_register drivers/net/ppp/ppp_generic.c:981 [inline] (&pn->all_ppp_mutex){+.+.}, at: [<00000000873fdeba>] ppp_dev_configure+0x74e/0xdd0 drivers/net/ppp/ppp_generic.c:1066 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&pn->all_ppp_mutex); lock(&pn->all_ppp_mutex); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor6/27866: #0: (ppp_mutex){+.+.}, at: [<0000000090f3f213>] ppp_ioctl+0x16d/0x2a50 drivers/net/ppp/ppp_generic.c:598 #1: (rtnl_mutex){+.+.}, at: [<000000004086d275>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72 #2: (&pn->all_ppp_mutex){+.+.}, at: [<00000000873fdeba>] ppp_unit_register drivers/net/ppp/ppp_generic.c:981 [inline] #2: (&pn->all_ppp_mutex){+.+.}, at: [<00000000873fdeba>] ppp_dev_configure+0x74e/0xdd0 drivers/net/ppp/ppp_generic.c:1066 stack backtrace: CPU: 1 PID: 27866 Comm: syz-executor6 Not tainted 4.15.0-rc6+ #250 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_deadlock_bug kernel/locking/lockdep.c:1756 [inline] check_deadlock kernel/locking/lockdep.c:1800 [inline] validate_chain kernel/locking/lockdep.c:2396 [inline] __lock_acquire+0xe8f/0x3e00 kernel/locking/lockdep.c:3426 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3914 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 ppp_dev_uninit+0x23a/0x440 drivers/net/ppp/ppp_generic.c:1369 register_netdevice+0x937/0x1010 net/core/dev.c:7746 ppp_unit_register drivers/net/ppp/ppp_generic.c:1009 [inline] ppp_dev_configure+0x964/0xdd0 drivers/net/ppp/ppp_generic.c:1066 ppp_create_interface drivers/net/ppp/ppp_generic.c:3027 [inline] ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:866 [inline] ppp_ioctl+0x178f/0x2a50 drivers/net/ppp/ppp_generic.c:602 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x23/0x9a RIP: 0033:0x452ac9 RSP: 002b:00007f61bf3b8c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f61bf3b8aa0 RCX: 0000000000452ac9 RDX: 0000000020001000 RSI: 00000000c004743e RDI: 0000000000000014 RBP: 00007f61bf3b8a90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b767a R13: 00007f61bf3b8bc8 R14: 00000000004b767a R15: 0000000000000000 audit: type=1326 audit(1515289861.721:2726): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515289861.727:2727): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=31 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x0 audit: type=1326 audit(1515289861.775:2728): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=0 arch=c000003e syscall=317 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515289861.776:2729): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515289861.776:2730): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515289861.780:2731): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515289861.781:2732): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=27756 comm="syz-executor1" exe="/root/syz-executor1" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000