bisecting fixing commit since cc4c818b2219c58af5f0ca59f3e9f02c48bc0b65 building syzkaller on cdde748628a830b9236db9890a9fea0764bde4fb testing commit cc4c818b2219c58af5f0ca59f3e9f02c48bc0b65 with gcc (GCC) 8.1.0 kernel signature: ed0b3cb12649639efa2d608b967667fb1b3dd637b083c19c9ede0a815740201d all runs: crashed: INFO: task hung in do_exit testing current HEAD a083db76118d20d070794ecf79af17843406c3f6 testing commit a083db76118d20d070794ecf79af17843406c3f6 with gcc (GCC) 8.1.0 kernel signature: 9ee4118288cb57562a21397c5710504f40dfac04c76f48383a916db173c2e4b0 all runs: crashed: INFO: task hung in do_exit revisions tested: 2, total time: 31m42.929631914s (build: 18m47.155051572s, test: 11m47.258499583s) the crash still happens on HEAD commit msg: Linux 4.19.107 crash: INFO: task hung in do_exit IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: 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.5:7290 blocked for more than 140 seconds. Not tainted 4.19.107-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28136 7290 7215 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:2583 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:00007ffe5533c1e8 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.5:7295 blocked for more than 140 seconds. Not tainted 4.19.107-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28200 7295 7215 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:2583 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:00007f28a795dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000006 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffd000 RBP: 000000000075bf20 R08: 0000000000000004 R09: 0000000000000000 R10: 0000000000000011 R11: 0000000000000246 R12: 00007f28a795e6d4 R13: 00000000004c5d1b R14: 00000000004da6d0 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1041: #0: 00000000034c10b6 (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4438 1 lock held by rsyslogd/6965: #0: 0000000032b55e86 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 2 locks held by getty/7088: #0: 00000000d6e9cef0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000080c0aee8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 2 locks held by getty/7089: #0: 0000000036f433e2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000001b260dc3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 2 locks held by getty/7090: #0: 00000000bfab444a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000007c641f7c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 2 locks held by getty/7091: #0: 00000000af5eedd9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000231c1ae0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 2 locks held by getty/7092: #0: 000000008a207998 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000cd051fbf (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 2 locks held by getty/7093: #0: 00000000598bca2a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000851ae39a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 2 locks held by getty/7094: #0: 00000000f3dcc45c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000026ad0cc3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x1910 drivers/tty/n_tty.c:2154 1 lock held by syz-executor.5/7290: #0: 00000000fae7fc18 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 00000000fae7fc18 (&mm->mmap_sem){++++}, at: do_exit+0x617/0x2d20 kernel/exit.c:867 1 lock held by syz-executor.5/7295: #0: 00000000fae7fc18 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:512 [inline] #0: 00000000fae7fc18 (&mm->mmap_sem){++++}, at: do_exit+0x617/0x2d20 kernel/exit.c:867 1 lock held by syz-executor.5/7302: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1041 Comm: khungtaskd Not tainted 4.19.107-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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 7302 Comm: syz-executor.5 Not tainted 4.19.107-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0xc4/0x4980 kernel/locking/lockdep.c:3279 Code: f2 c7 40 1c f3 f3 f3 f3 65 48 8b 04 25 28 00 00 00 48 89 84 24 b8 01 00 00 31 c0 48 c7 c0 60 d5 4e 88 48 c1 e8 03 0f b6 14 10 <48> c7 c0 60 d5 4e 88 83 e0 07 83 c0 03 65 4c 8b 34 25 40 ee 01 00 RSP: 0018:ffff888079807680 EFLAGS: 00000806 RAX: 1ffffffff109daac RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000004 RSI: 0000000000000000 RDI: ffff8880a07166d0 RBP: ffff888079807870 R08: 0000000000000001 R09: 0000000000000000 R10: ffff888079807a98 R11: ffff8880a0716677 R12: 0000000000000000 R13: ffff8880a07166d0 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f28a793d700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000007350a000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x173/0x3d0 kernel/locking/lockdep.c:3903 __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:5682 call_mmap include/linux/fs.h:1825 [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:00007f28a793cc78 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: 00007f28a793d6d4 R13: 00000000004c5d71 R14: 00000000004da748 R15: 00000000ffffffff