bisecting fixing commit since 58b454ebf81e5ae9391957d99cf89566d9eec1b1 building syzkaller on b0e8efcb4b0aac61f4647a76bbe54a5d38a370ba testing commit 58b454ebf81e5ae9391957d99cf89566d9eec1b1 with gcc (GCC) 8.1.0 kernel signature: 628cc230cbb93a3f4375b5c506b0b3489cc4ea5e all runs: crashed: INFO: task hung in do_exit testing current HEAD 43598c571e7ed29e4c81e35b4a870fe6b9f8d58e testing commit 43598c571e7ed29e4c81e35b4a870fe6b9f8d58e with gcc (GCC) 8.1.0 kernel signature: 18f4e423533963551eebb65718d2c2a2d101d3d3 all runs: crashed: INFO: task hung in do_exit revisions tested: 2, total time: 31m8.433776471s (build: 15m47.767099688s, test: 14m24.117348758s) the crash still happens on HEAD commit msg: Linux 4.14.156 crash: INFO: task hung in do_exit IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 INFO: task syz-executor.2:7009 blocked for more than 140 seconds. Not tainted 4.14.156-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28264 7009 6783 0x80000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x786/0x1d30 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x1fc/0x390 kernel/locking/rwsem-xadd.c:309 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:66 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:511 [inline] do_exit+0x38c/0x2e80 kernel/exit.c:861 do_group_exit+0xf4/0x2f0 kernel/exit.c:977 get_signal+0x2fe/0x1b40 kernel/signal.c:2413 do_signal+0x7f/0x19a0 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x114/0x1b0 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x418/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x458c7a RSP: 002b:00007ffe8d112ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 0000000000458c7a RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000 RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000 INFO: task syz-executor.2:7013 blocked for more than 140 seconds. Not tainted 4.14.156-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29176 7013 6783 0x80000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x786/0x1d30 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x1fc/0x390 kernel/locking/rwsem-xadd.c:309 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:66 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:511 [inline] do_exit+0x38c/0x2e80 kernel/exit.c:861 do_group_exit+0xf4/0x2f0 kernel/exit.c:977 get_signal+0x2fe/0x1b40 kernel/signal.c:2413 do_signal+0x7f/0x19a0 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x114/0x1b0 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x418/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x458c29 RSP: 002b:00007f83ac16ccf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000073bf08 RCX: 0000000000458c29 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000073bf08 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000073bf0c R13: 00007ffe8d112d4f R14: 00007f83ac16d9c0 R15: 000000000073bf0c Showing all locks held in the system: 1 lock held by khungtaskd/1012: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4544 2 locks held by getty/6671: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6672: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6673: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6674: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6675: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6676: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 2 locks held by getty/6677: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x18b0 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.2/7009: #0: (&mm->mmap_sem){++++}, at: [] exit_mm kernel/exit.c:511 [inline] #0: (&mm->mmap_sem){++++}, at: [] do_exit+0x38c/0x2e80 kernel/exit.c:861 1 lock held by syz-executor.2/7013: #0: (&mm->mmap_sem){++++}, at: [] exit_mm kernel/exit.c:511 [inline] #0: (&mm->mmap_sem){++++}, at: [] do_exit+0x38c/0x2e80 kernel/exit.c:861 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1012 Comm: khungtaskd Not tainted 4.14.156-syzkaller #0 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+0xf7/0x13b lib/dump_stack.c:58 nmi_cpu_backtrace.cold.3+0x3e/0x76 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf4/0x118 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x522/0xb40 kernel/hung_task.c:274 kthread+0x33b/0x410 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 7023 Comm: syz-executor.2 Not tainted 4.14.156-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a5bfc0c0 task.stack: ffff8880a5e78000 RIP: 0010:hlock_class kernel/locking/lockdep.c:148 [inline] RIP: 0010:mark_lock+0x1/0x1210 kernel/locking/lockdep.c:3164 RSP: 0018:ffff8880a5e7f780 EFLAGS: 00000002 RAX: 0000000000000001 RBX: 0000000000000672 RCX: 1ffff11014b7f931 RDX: 0000000000000008 RSI: ffff8880a5bfc968 RDI: ffff8880a5bfc0c0 RBP: ffff8880a5e7f960 R08: ffff8880a5bfc988 R09: 0000000000000000 R10: 0000000000000028 R11: ffff8880a5bfc0c0 R12: ffff8880a5bfc92c R13: ffff8880a5bfc98a R14: 0000000000000001 R15: ffff8880a5bfc968 FS: 00007f83ac14c700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000625208 CR3: 0000000086761000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x173/0x400 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xef/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_mmap+0x4ae/0x1330 kernel/events/core.c:5411 call_mmap include/linux/fs.h:1782 [inline] mmap_region+0x7a7/0xfa0 mm/mmap.c:1723 do_mmap+0x544/0xe20 mm/mmap.c:1501 do_mmap_pgoff include/linux/mm.h:2173 [inline] vm_mmap_pgoff+0x181/0x200 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1551 [inline] SyS_mmap_pgoff+0x3ca/0x6b0 mm/mmap.c:1509 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x1c9/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x458c29 RSP: 002b:00007f83ac14bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000458c29 RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffd000 RBP: 000000000073bfa0 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000001011 R11: 0000000000000246 R12: 00007f83ac14c6d4 R13: 00000000004c4bb0 R14: 00000000004d87f8 R15: 00000000ffffffff Code: 84 a6 b7 00 00 48 8d 65 d8 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b e8 dd de 3c 00 eb d8 e8 f6 de 3c 00 eb 87 0f 1f 40 00 55 <4c> 8d 46 20 89 d1 48 b8 00 00 00 00 00 fc ff df 48 89 e5 41 57