bisecting fixing commit since cc4c818b2219c58af5f0ca59f3e9f02c48bc0b65 building syzkaller on cdde748628a830b9236db9890a9fea0764bde4fb testing commit cc4c818b2219c58af5f0ca59f3e9f02c48bc0b65 with gcc (GCC) 8.1.0 kernel signature: cf60e8ce71f204227c08e8a05906b86f1c16cab8caec338da946962c728c3a3e all runs: crashed: INFO: task hung in do_exit testing current HEAD 675cc038067f0e530471c56a7442935f84669d95 testing commit 675cc038067f0e530471c56a7442935f84669d95 with gcc (GCC) 8.1.0 kernel signature: 2bc0758b3fa6425ffaeaca2576ba663626a6dec81741d9eb346113cabe860cbd all runs: crashed: INFO: task hung in do_exit revisions tested: 2, total time: 31m49.698247943s (build: 16m54.124375921s, test: 13m55.274054978s) the crash still happens on HEAD commit msg: Linux 4.19.167 crash: INFO: task hung in do_exit IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not 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.2:6673 blocked for more than 140 seconds. Not tainted 4.19.167-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28136 6673 5713 0x80000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x21c/0x3e0 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:83 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:512 [inline] do_exit+0x61f/0x2d70 kernel/exit.c:877 do_group_exit+0xf4/0x2f0 kernel/exit.c:993 get_signal+0x313/0x1a30 kernel/signal.c:2589 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598fa Code: Bad RIP value. RSP: 002b:00007ffe0553b2d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00000000004598fa 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.2:6674 blocked for more than 140 seconds. Not tainted 4.19.167-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28200 6674 5713 0x80000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x21c/0x3e0 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:83 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:512 [inline] do_exit+0x61f/0x2d70 kernel/exit.c:877 do_group_exit+0xf4/0x2f0 kernel/exit.c:993 get_signal+0x313/0x1a30 kernel/signal.c:2589 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598a9 Code: Bad RIP value. RSP: 002b:00007f25cd79ccf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 00000000004598a9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c R13: 00007ffe0553b37f R14: 00007f25cd79d9c0 R15: 000000000075bf2c INFO: task syz-executor.1:6678 blocked for more than 140 seconds. Not tainted 4.19.167-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28136 6678 5717 0x80000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x21c/0x3e0 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:83 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:512 [inline] do_exit+0x61f/0x2d70 kernel/exit.c:877 do_group_exit+0xf4/0x2f0 kernel/exit.c:993 get_signal+0x313/0x1a30 kernel/signal.c:2589 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598fa Code: Bad RIP value. RSP: 002b:00007ffe5cdb69e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00000000004598fa 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.1:6679 blocked for more than 140 seconds. Not tainted 4.19.167-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28008 6679 5717 0x80000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x21c/0x3e0 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:83 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:512 [inline] do_exit+0x61f/0x2d70 kernel/exit.c:877 do_group_exit+0xf4/0x2f0 kernel/exit.c:993 get_signal+0x313/0x1a30 kernel/signal.c:2589 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598a9 Code: Bad RIP value. RSP: 002b:00007f0ec1656cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 00000000004598a9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c R13: 00007ffe5cdb6a8f R14: 00007f0ec16579c0 R15: 000000000075bf2c INFO: task syz-executor.0:6692 blocked for more than 140 seconds. Not tainted 4.19.167-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28136 6692 5715 0x80000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x21c/0x3e0 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:83 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:512 [inline] do_exit+0x61f/0x2d70 kernel/exit.c:877 do_group_exit+0xf4/0x2f0 kernel/exit.c:993 get_signal+0x313/0x1a30 kernel/signal.c:2589 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598fa Code: Bad RIP value. RSP: 002b:00007ffd4e10d668 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00000000004598fa 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.0:6694 blocked for more than 140 seconds. Not tainted 4.19.167-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28200 6694 5715 0x80000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x21c/0x3e0 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:83 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 exit_mm kernel/exit.c:512 [inline] do_exit+0x61f/0x2d70 kernel/exit.c:877 do_group_exit+0xf4/0x2f0 kernel/exit.c:993 get_signal+0x313/0x1a30 kernel/signal.c:2589 do_signal+0x87/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x114/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598a9 Code: Bad RIP value. RSP: 002b:00007fb77131fcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 00000000004598a9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c R13: 00007ffd4e10d70f R14: 00007fb7713209c0 R15: 000000000075bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1045: #0: 0000000052f0f29c (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 2 locks held by kworker/u4:4/2300: #0: 000000006d50ce8a (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1824 [inline] #0: 000000006d50ce8a (&rq->lock){-.-.}, at: __schedule+0x1f5/0x1c10 kernel/sched/core.c:3455 #1: 000000001b6e52e0 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}, at: process_one_work+0x792/0x1670 kernel/workqueue.c:2130 1 lock held by in:imklog/5339: #0: 00000000f7006766 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 1 lock held by syz-executor.2/6673: #0: 0000000093c5a8c9 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 0000000093c5a8c9 (&mm->mmap_sem){++++}, at: do_exit+0x61f/0x2d70 kernel/exit.c:877 1 lock held by syz-executor.2/6674: #0: 0000000093c5a8c9 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 0000000093c5a8c9 (&mm->mmap_sem){++++}, at: do_exit+0x61f/0x2d70 kernel/exit.c:877 1 lock held by syz-executor.2/6675: 1 lock held by syz-executor.1/6678: #0: 0000000089f59745 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 0000000089f59745 (&mm->mmap_sem){++++}, at: do_exit+0x61f/0x2d70 kernel/exit.c:877 1 lock held by syz-executor.1/6679: #0: 0000000089f59745 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 0000000089f59745 (&mm->mmap_sem){++++}, at: do_exit+0x61f/0x2d70 kernel/exit.c:877 5 locks held by syz-executor.1/6681: 1 lock held by syz-executor.0/6692: #0: 000000002a5760e3 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 000000002a5760e3 (&mm->mmap_sem){++++}, at: do_exit+0x61f/0x2d70 kernel/exit.c:877 1 lock held by syz-executor.0/6694: #0: 000000002a5760e3 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 000000002a5760e3 (&mm->mmap_sem){++++}, at: do_exit+0x61f/0x2d70 kernel/exit.c:877 1 lock held by syz-executor.0/6696: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1045 Comm: khungtaskd Not tainted 4.19.167-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.4+0x3e/0x76 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xe6/0x11a 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 6681 Comm: syz-executor.1 Not tainted 4.19.167-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:separate_irq_context kernel/locking/lockdep.c:3044 [inline] RIP: 0010:__lock_acquire+0x85c/0x4980 kernel/locking/lockdep.c:3406 Code: 89 d2 48 c1 ea 03 80 3c 02 00 0f 85 6c 2c 00 00 48 8b 54 24 78 4d 89 2a 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 0f b6 04 02 <84> c0 74 08 3c 03 0f 8e cf 2b 00 00 41 8b 86 80 08 00 00 85 c0 0f RSP: 0018:ffff8881dfef7680 EFLAGS: 00000802 RAX: 0000000000000000 RBX: 00000000000006f2 RCX: 1ffff1103bc7d5a2 RDX: 1ffff1103bc7d598 RSI: ffff8881de3eacf0 RDI: ffffffff89839140 RBP: ffff8881dfef7870 R08: ffff8881de3ead10 R09: 0000000000000001 R10: ffff8881de3eacf0 R11: 0000000000000000 R12: 00000000000006f2 R13: 785f29aa7c5c2124 R14: ffff8881de3ea440 R15: 0000000000000004 FS: 00007f0ec1636700(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055907932db38 CR3: 00000001df5d2004 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x173/0x3d0 kernel/locking/lockdep.c:3907 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf5/0x1210 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 perf_mmap+0x65b/0x1670 kernel/events/core.c:5689 call_mmap include/linux/fs.h:1826 [inline] mmap_region+0x9b7/0x1470 mm/mmap.c:1757 do_mmap+0x6b5/0xea0 mm/mmap.c:1530 do_mmap_pgoff include/linux/mm.h:2326 [inline] vm_mmap_pgoff+0x195/0x210 mm/util.c:357 ksys_mmap_pgoff+0x3c6/0x650 mm/mmap.c:1580 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598a9 Code: 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 4b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f0ec1635c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00000000004598a9 RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffd000 RBP: 000000000075bfc8 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000001011 R11: 0000000000000246 R12: 00007f0ec16366d4 R13: 00000000004c5df1 R14: 00000000004da7c8 R15: 00000000ffffffff