INFO: task syz-executor.4:30011 blocked for more than 140 seconds. Not tainted 4.14.198-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D28912 30011 6373 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3384 schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1731 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x272/0x430 kernel/sched/completion.c:123 ucma_close+0xfc/0x340 drivers/infiniband/core/ucma.c:1749 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x417781 RSP: 002b:00007ffcac4fd4e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000417781 RDX: 0000000000000000 RSI: 000000000000086e RDI: 0000000000000005 RBP: 0000000000000001 R08: 00000000216a486e R09: 00000000216a4872 R10: 00007ffcac4fd5c0 R11: 0000000000000293 R12: ffffffffffffffff R13: 00000000001a9ca6 R14: 00000000000003e8 R15: 000000000118bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1067: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1067 Comm: khungtaskd Not tainted 4.14.198-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x283 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5b9/0xb40 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3651 Comm: systemd-journal Not tainted 4.14.198-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880942c0300 task.stack: ffff8880942c8000 RIP: 0010:memcmp+0x62/0xb0 lib/string.c:861 RSP: 0018:ffff8880942cfaa0 EFLAGS: 00000246 RAX: 00000000000000ff RBX: ffff8880942cfb45 RCX: 0000000000000005 RDX: 0000000000000000 RSI: ffff888099c1e14d RDI: ffff8880942cfb40 RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffff8880942c0300 R12: ffff8880942cfb88 R13: 0000000000000009 R14: ffff8880942cfb40 R15: ffff888099c1e130 FS: 00007f8ce80d18c0(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8ce3ee8000 CR3: 0000000094b7b000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: find_stack lib/stackdepot.c:180 [inline] depot_save_stack+0x10d/0x3e3 lib/stackdepot.c:229 save_stack mm/kasan/kasan.c:453 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0x139/0x160 mm/kasan/kasan.c:551 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc_track_caller+0x155/0x400 mm/slab.c:3735 kmemdup+0x23/0x50 mm/util.c:118 kmemdup include/linux/string.h:445 [inline] selinux_cred_prepare+0x44/0xa0 security/selinux/hooks.c:3849 security_prepare_creds+0x76/0xb0 security/security.c:1008 prepare_creds+0x2ef/0x490 kernel/cred.c:282 SYSC_faccessat fs/open.c:365 [inline] SyS_faccessat+0x7b/0x680 fs/open.c:353 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f8ce738d9c7 RSP: 002b:00007ffd549fcfa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000015 RAX: ffffffffffffffda RBX: 00007ffd549fffd0 RCX: 00007f8ce738d9c7 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00005570edc749a3 RBP: 00007ffd549fd0f0 R08: 00005570edc6a3e5 R09: 0000000000000018 R10: 0000000000000060 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00005570ee5b78c0 R15: 00007ffd549fd5e0 Code: 83 e2 07 0f b6 04 28 38 d0 7f 04 84 c0 75 54 48 89 f2 48 89 f1 0f b6 03 48 c1 ea 03 83 e1 07 0f b6 14 2a 38 ca 7f 04 84 d2 75 1e <0f> b6 16 29 d0 74 b7 48 83 c4 10 5b 5d 41 5c c3 48 83 c4 10 31