INFO: task syz-executor5:14653 blocked for more than 140 seconds. Not tainted 4.19.0-rc4+ #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D25632 14653 5481 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473 schedule+0xfe/0x460 kernel/sched/core.c:3517 __rwsem_down_write_failed_common+0xbb9/0x1670 kernel/locking/rwsem-xadd.c:566 rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0xa5/0x130 kernel/locking/rwsem.c:72 inode_lock include/linux/fs.h:738 [inline] chmod_common+0x1b1/0x590 fs/open.c:535 do_fchmodat+0xc3/0x160 fs/open.c:579 __do_sys_chmod fs/open.c:597 [inline] __se_sys_chmod fs/open.c:595 [inline] __x64_sys_chmod+0x5c/0x80 fs/open.c:595 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457679 Code: ff ff e8 5a 28 00 00 e9 45 fe ff ff cc cc cc cc cc 48 8b 4c 24 10 48 8b 11 64 48 8b 1c 25 f8 ff ff ff 8b b2 d8 00 00 00 8d 7e 89 ba d8 00 00 00 83 fe 01 75 13 0f b6 93 c0 00 00 00 84 d2 74 RSP: 002b:00007fd67cb8bc78 EFLAGS: 00000246 ORIG_RAX: 000000000000005a RAX: ffffffffffffffda RBX: 00007fd67cb8c6d4 RCX: 0000000000457679 RDX: 0000000000000000 RSI: 00000000ffffff8c RDI: 00000000200006c0 RBP: 000000000072c0e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004cc388 R14: 00000000004bd4df R15: 0000000000000003 Showing all locks held in the system: 1 lock held by khungtaskd/982: #0: 00000000f2de9d79 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4435 1 lock held by rsyslogd/5306: 2 locks held by getty/5428: #0: 00000000abf04be8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000025048578 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5429: #0: 000000006f4d3021 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000413dfd2a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5430: #0: 00000000b37d9557 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000062b7ba6c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5431: #0: 000000003deae2f5 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000330da7a7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5432: #0: 00000000cae68c8d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000008161c1d6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5433: #0: 000000004682732a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b146aff7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5434: #0: 00000000c65c82e7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000008cbd2385 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor5/14588: #0: 000000006542e597 (sb_writers#21){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 000000006542e597 (sb_writers#21){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 000000002e983a18 (&sb->s_type->i_mutex_key#25){++++}, at: inode_lock include/linux/fs.h:738 [inline] #1: 000000002e983a18 (&sb->s_type->i_mutex_key#25){++++}, at: chmod_common+0x1b1/0x590 fs/open.c:535 1 lock held by syz-executor5/14651: #0: 00000000084e2184 (&type->s_umount_key#59/1){+.+.}, at: alloc_super fs/super.c:226 [inline] #0: 00000000084e2184 (&type->s_umount_key#59/1){+.+.}, at: sget_userns+0x2e5/0xf10 fs/super.c:519 2 locks held by syz-executor5/14653: #0: 000000006542e597 (sb_writers#21){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 000000006542e597 (sb_writers#21){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 000000002e983a18 (&sb->s_type->i_mutex_key#25){++++}, at: inode_lock include/linux/fs.h:738 [inline] #1: 000000002e983a18 (&sb->s_type->i_mutex_key#25){++++}, at: chmod_common+0x1b1/0x590 fs/open.c:535 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 982 Comm: khungtaskd Not tainted 4.19.0-rc4+ #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+0x1c4/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb3e/0x1050 kernel/hung_task.c:265 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57