bisecting fixing commit since cc4c818b2219c58af5f0ca59f3e9f02c48bc0b65 building syzkaller on cdde748628a830b9236db9890a9fea0764bde4fb testing commit cc4c818b2219c58af5f0ca59f3e9f02c48bc0b65 with gcc (GCC) 8.1.0 kernel signature: f5f34e393279cadd193921e35a929d39f65913f4a0e442b6af22277ced403aa1 all runs: crashed: INFO: task hung in do_exit testing current HEAD 765675379b6253b6901563e649a2f87d28ada3ff testing commit 765675379b6253b6901563e649a2f87d28ada3ff with gcc (GCC) 8.1.0 kernel signature: ff50775138cc041614d94633306febcfb6c52dacccc2d6a3202569089ec7c632 all runs: crashed: INFO: task hung in do_exit revisions tested: 2, total time: 31m26.057105305s (build: 18m5.849503055s, test: 12m1.428865799s) the crash still happens on HEAD commit msg: Linux 4.19.119 crash: INFO: task hung in do_exit IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 INFO: task syz-executor.0:7320 blocked for more than 140 seconds. Not tainted 4.19.119-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28136 7320 6395 0x80000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 schedule+0x7f/0x1b0 kernel/sched/core.c:3559 __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+0x617/0x2d20 kernel/exit.c:867 do_group_exit+0xf4/0x2f0 kernel/exit.c:983 get_signal+0x313/0x1a00 kernel/signal.c:2588 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: 0033:0x45987a Code: Bad RIP value. RSP: 002b:00007fff7a9c0a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 000000000045987a 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.0:7322 blocked for more than 140 seconds. Not tainted 4.19.119-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28200 7322 6395 0x80000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 schedule+0x7f/0x1b0 kernel/sched/core.c:3559 __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+0x617/0x2d20 kernel/exit.c:867 do_group_exit+0xf4/0x2f0 kernel/exit.c:983 get_signal+0x313/0x1a00 kernel/signal.c:2588 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: 0033:0x459829 Code: Bad RIP value. RSP: 002b:00007ff8527e2cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c R13: 00007fff7a9c0abf R14: 00007ff8527e39c0 R15: 000000000075bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1033: #0: 0000000066d07e01 (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 1 lock held by in:imklog/5904: #0: 00000000012a3b40 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 1 lock held by syz-executor.0/7320: #0: 00000000077e779e (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 00000000077e779e (&mm->mmap_sem){++++}, at: do_exit+0x617/0x2d20 kernel/exit.c:867 1 lock held by syz-executor.0/7322: #0: 00000000077e779e (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 00000000077e779e (&mm->mmap_sem){++++}, at: do_exit+0x617/0x2d20 kernel/exit.c:867 1 lock held by syz-executor.0/7324: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1033 Comm: khungtaskd Not tainted 4.19.119-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+0x324/0x3e0 kernel/kthread.c:246 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: 7324 Comm: syz-executor.0 Not tainted 4.19.119-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:kasan_check_read+0x12/0x20 mm/kasan/kasan.c:273 Code: e3 07 49 39 c3 0f 8c 1a ff ff ff eb 94 48 89 c3 eb a2 4c 89 c8 eb 85 90 55 89 f6 31 d2 48 89 e5 48 8b 4d 08 e8 3f fe ff ff 5d 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 89 f6 ba 01 00 00 00 RSP: 0018:ffff88809f3ffaa0 EFLAGS: 00000246 RAX: ffffed1012651c76 RBX: ffff88809328e300 RCX: ffffffff81765aa6 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88809328e3a8 RBP: ffff88809f3ffb98 R08: ffffed1012651c76 R09: ffffed1012651c75 R10: ffffed1012651c75 R11: ffff88809328e3ab R12: ffff88809f3ffb70 R13: ffff8880933fb630 R14: ffff8880933fb340 R15: ffff88809328e3a8 FS: 00007ff8527c2700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055ebccc2ad80 CR3: 000000009443e000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: 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:2314 [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: 0033:0x459829 Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff8527c1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffd000 RBP: 000000000075bfc8 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000001011 R11: 0000000000000246 R12: 00007ff8527c26d4 R13: 00000000004c5d71 R14: 00000000004da748 R15: 00000000ffffffff