RAX: ffffffffffffffda RBX: 0000000020000310 RCX: 000000000040fe67 RDX: 0000000000000048 RSI: 0000000020010000 RDI: 0000000000000015 RBP: 0000000000000000 R08: 0000000020000318 R09: 00000000fbad8001 R10: 0000000000010000 R11: 0000000000000293 R12: 0000000000000015 R13: 0000000000000001 R14: 00000000004d3840 R15: 0000000000000005 INFO: task syz-executor2:12510 blocked for more than 140 seconds. Not tainted 4.18.0-rc3-next-20180706+ #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D20160 12510 4489 0x00000004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x87c/0x1ed0 kernel/sched/core.c:3501 schedule+0xfb/0x450 kernel/sched/core.c:3545 io_schedule+0x1c/0x70 kernel/sched/core.c:5168 wait_on_page_bit_common+0x4ff/0x7a0 mm/filemap.c:1079 wait_on_page_bit mm/filemap.c:1112 [inline] wait_on_page_locked include/linux/pagemap.h:530 [inline] wait_on_page_read mm/filemap.c:2668 [inline] do_read_cache_page+0x97a/0x13c0 mm/filemap.c:2707 read_cache_page_gfp+0x6f/0x90 mm/filemap.c:2810 btrfs_read_disk_super fs/btrfs/volumes.c:1190 [inline] btrfs_scan_one_device+0x274/0xbf0 fs/btrfs/volumes.c:1244 btrfs_mount_root+0xd12/0x1eb0 fs/btrfs/super.c:1569 legacy_get_tree+0x118/0x440 fs/fs_context.c:659 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1751 vfs_kern_mount.part.36+0x119/0x190 fs/namespace.c:3191 vfs_kern_mount+0x4a/0x70 fs/namespace.c:3171 btrfs_mount+0x4b7/0x217c fs/btrfs/super.c:1671 legacy_get_tree+0x118/0x440 fs/fs_context.c:659 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1751 do_new_mount fs/namespace.c:2567 [inline] do_mount+0x6c1/0x1fb0 fs/namespace.c:2889 ksys_mount+0x12d/0x140 fs/namespace.c:3105 __do_sys_mount fs/namespace.c:3119 [inline] __se_sys_mount fs/namespace.c:3116 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3116 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4585da Code: Bad RIP value. RSP: 002b:00007f7e00079a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f7e00079b30 RCX: 00000000004585da RDX: 00007f7e00079ad0 RSI: 0000000020000100 RDI: 00007f7e00079af0 RBP: 0000000020000100 R08: 00007f7e00079b30 R09: 00007f7e00079ad0 R10: 0000000000000001 R11: 0000000000000206 R12: 0000000000000015 R13: 0000000000000001 R14: 00000000004d3840 R15: 0000000000000005 INFO: lockdep is turned off. NMI backtrace for cpu 1 CPU: 1 PID: 897 Comm: khungtaskd Not tainted 4.18.0-rc3-next-20180706+ #1 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+0x1c9/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.5+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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:143 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb39/0x10b0 kernel/hung_task.c:265 kthread+0x345/0x410 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 12522 Comm: loop2 Not tainted 4.18.0-rc3-next-20180706+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:69 [inline] RIP: 0010:write_comp_data+0x22/0x70 kernel/kcov.c:122 Code: d4 ce ca ff 90 90 90 90 55 65 4c 8b 04 25 40 ee 01 00 65 8b 05 cf 73 85 7e 48 89 e5 a9 00 01 1f 00 75 51 41 8b 80 98 12 00 00 <83> f8 03 75 45 49 8b 80 a0 12 00 00 45 8b 80 9c 12 00 00 4c 8b 08 RSP: 0018:ffff88018fdce598 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffea0006d3d088 RCX: ffffffff8199fe46 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: ffff88018fdce598 R08: ffff8801aa1aa480 R09: ffffed0031fb9cc5 R10: ffffed0031fb9cc5 R11: 0000000000000003 R12: ffff88018fdce948 R13: 1ffff10031fb9d01 R14: 0000000000000000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001c639e000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __sanitizer_cov_trace_const_cmp4+0x16/0x20 kernel/kcov.c:188 page_cache_get_speculative include/linux/pagemap.h:195 [inline] find_get_entry+0x6a6/0x1120 mm/filemap.c:1411 find_lock_entry+0xe6/0x8c0 mm/filemap.c:1457 shmem_getpage_gfp+0x3cd/0x3ec0 mm/shmem.c:1610 shmem_getpage mm/shmem.c:132 [inline] shmem_file_read_iter+0x399/0x1090 mm/shmem.c:2433 call_read_iter include/linux/fs.h:1816 [inline] do_iter_readv_writev+0x790/0xa90 fs/read_write.c:678 do_iter_read+0x26e/0x650 fs/read_write.c:922 vfs_iter_read+0x77/0xb0 fs/read_write.c:936 lo_read_simple drivers/block/loop.c:350 [inline] do_req_filebacked drivers/block/loop.c:615 [inline] loop_handle_cmd drivers/block/loop.c:1786 [inline] loop_queue_work+0x9ce/0x3afc drivers/block/loop.c:1800 kthread_worker_fn+0x35f/0xa50 kernel/kthread.c:656 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:892 kthread+0x345/0x410 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.274 msecs