futex_wake_op: syz-executor.1 tries to shift op by -1; fix this program INFO: task syz-executor.3:14039 blocked for more than 140 seconds. Not tainted 4.19.56 #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D24056 14039 1 0x80000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x80d/0x1c70 kernel/sched/core.c:3474 schedule+0x92/0x1c0 kernel/sched/core.c:3518 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3576 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x726/0x1300 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 acct_get kernel/acct.c:161 [inline] slow_acct_process kernel/acct.c:577 [inline] acct_process+0x2e5/0x61e kernel/acct.c:605 do_exit+0x17be/0x2fa0 kernel/exit.c:866 do_group_exit+0x135/0x370 kernel/exit.c:979 get_signal+0x3ec/0x1fc0 kernel/signal.c:2574 do_signal+0x95/0x1960 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x244/0x2c0 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+0x53d/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4134aa Code: 83 0d 01 00 00 88 44 1c 30 48 8d 43 01 48 83 f8 28 0f 83 f4 00 00 00 48 89 74 24 28 c6 44 1c 31 00 48 8d 44 24 30 48 89 44 24 <08> 48 8b 84 24 98 00 00 00 48 89 04 24 48 8b 44 24 68 48 89 44 24 RSP: 002b:00007ffff4d38ba8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 00000000027eb940 RCX: 00000000004134aa RDX: 0000000040000000 RSI: 00007ffff4d38be0 RDI: ffffffffffffffff RBP: 00000000000035aa R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffff4d38be0 R14: 00000000027eb99b R15: 00007ffff4d38bf0 Showing all locks held in the system: 1 lock held by khungtaskd/1030: #0: 0000000073f718b3 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4435 2 locks held by getty/7733: #0: 00000000519690f0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 00000000642f56b0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7734: #0: 00000000ed592284 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 0000000019757d67 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7735: #0: 00000000e6181a1a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 000000004d802788 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7736: #0: 00000000cc94a60b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 000000002794f1b3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7737: #0: 00000000a688314b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 0000000070e5a5a1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7738: #0: 000000006a51f4b4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 00000000b6d9f010 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 2 locks held by getty/7739: #0: 00000000073871ce (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363 #1: 000000004f827171 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154 1 lock held by syz-executor.3/14039: #0: 00000000ed1c8588 (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000ed1c8588 (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000ed1c8588 (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 3 locks held by syz-executor.3/12890: #0: 00000000ed1c8588 (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000ed1c8588 (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000ed1c8588 (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 #1: 00000000ec4a794e (sb_writers#4){.+.+}, at: file_start_write_trylock include/linux/fs.h:2780 [inline] #1: 00000000ec4a794e (sb_writers#4){.+.+}, at: do_acct_process+0xf37/0x1150 kernel/acct.c:517 #2: 000000007681d426 (&sb->s_type->i_mutex_key#9){++++}, at: inode_trylock include/linux/fs.h:767 [inline] #2: 000000007681d426 (&sb->s_type->i_mutex_key#9){++++}, at: ext4_file_write_iter+0x23f/0x1060 fs/ext4/file.c:232 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1030 Comm: khungtaskd Not tainted 4.19.56 #28 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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 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+0x9df/0xee0 kernel/hung_task.c:287 kthread+0x354/0x420 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 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60