RBP: 00007fe6b476fa90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b767a R13: 00007fe6b476fbc8 R14: 00000000004b767a R15: 0000000000000000 ============================================ WARNING: possible recursive locking detected 4.15.0-rc6-mm1+ #51 Not tainted -------------------------------------------- syz-executor3/13725 is trying to acquire lock: (&pn->all_ppp_mutex){+.+.}, at: [<0000000083415ef1>] ppp_dev_uninit+0x1be/0x390 drivers/net/ppp/ppp_generic.c:1369 but task is already holding lock: (&pn->all_ppp_mutex){+.+.}, at: [<000000005f4d1d30>] ppp_unit_register drivers/net/ppp/ppp_generic.c:981 [inline] (&pn->all_ppp_mutex){+.+.}, at: [<000000005f4d1d30>] ppp_dev_configure+0x6a4/0xc40 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-executor3/13725: #0: (ppp_mutex){+.+.}, at: [<000000000e49360c>] ppp_ioctl+0x9e/0x2200 drivers/net/ppp/ppp_generic.c:598 #1: (rtnl_mutex){+.+.}, at: [<000000005acb6c62>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 #2: (&pn->all_ppp_mutex){+.+.}, at: [<000000005f4d1d30>] ppp_unit_register drivers/net/ppp/ppp_generic.c:981 [inline] #2: (&pn->all_ppp_mutex){+.+.}, at: [<000000005f4d1d30>] ppp_dev_configure+0x6a4/0xc40 drivers/net/ppp/ppp_generic.c:1066 stack backtrace: CPU: 0 PID: 13725 Comm: syz-executor3 Not tainted 4.15.0-rc6-mm1+ #51 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+0x137/0x198 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+0xec3/0x3cf0 kernel/locking/lockdep.c:3426 lock_acquire+0x16b/0x420 kernel/locking/lockdep.c:3914 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xec/0x1550 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 ppp_dev_uninit+0x1be/0x390 drivers/net/ppp/ppp_generic.c:1369 register_netdevice+0x8bf/0xf30 net/core/dev.c:7835 ppp_unit_register drivers/net/ppp/ppp_generic.c:1009 [inline] ppp_dev_configure+0x854/0xc40 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+0x1491/0x2200 drivers/net/ppp/ppp_generic.c:602 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x190/0xfe0 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:00007fe6b476fc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fe6b476faa0 RCX: 0000000000452ac9 RDX: 0000000020001000 RSI: 00000000c004743e RDI: 0000000000000014 RBP: 00007fe6b476fa90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b767a R13: 00007fe6b476fbc8 R14: 00000000004b767a R15: 0000000000000000 audit: type=1326 audit(1515236312.777:1012): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=267 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.777:1013): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.778:1014): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.783:1015): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=9 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.783:1016): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.783:1017): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.791:1018): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=257 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.791:1019): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000 audit: type=1326 audit(1515236312.791:1020): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13619 comm="syz-executor5" exe="/root/syz-executor5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452ac9 code=0x7ffc0000