bisecting fixing commit since 3ffe1e79c174b2093f7ee3df589a7705572c9620 building syzkaller on acb51638141ff960f547431757130749bc176bc0 testing commit 3ffe1e79c174b2093f7ee3df589a7705572c9620 with gcc (GCC) 8.1.0 kernel signature: 2dc2d151c62020586f4c15373d60056b597402b7fb843d10d35468312d12cb8c all runs: crashed: INFO: task hung in p9_fd_close testing current HEAD b850307b279cbd12ab8c654d1a3dfe55319cc475 testing commit b850307b279cbd12ab8c654d1a3dfe55319cc475 with gcc (GCC) 8.1.0 kernel signature: b499351a0d47daf465a1fa27b291fbc0e6015c4613240678a114411848d411d0 all runs: crashed: INFO: task hung in p9_fd_close revisions tested: 2, total time: 31m48.17235452s (build: 16m29.19256047s, test: 14m33.345029785s) the crash still happens on HEAD commit msg: Linux 4.14.184 crash: INFO: task hung in p9_fd_close IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 INFO: task syz-executor.0:7067 blocked for more than 140 seconds. Not tainted 4.14.184-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D26664 7067 6239 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x6e8/0xcc0 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x263/0x440 kernel/sched/completion.c:144 flush_work+0x38b/0x720 kernel/workqueue.c:2893 __cancel_work_timer+0x286/0x420 kernel/workqueue.c:2964 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3000 p9_conn_destroy net/9p/trans_fd.c:873 [inline] p9_fd_close+0x26f/0x410 net/9p/trans_fd.c:899 p9_client_create+0x99b/0xf40 net/9p/client.c:1095 v9fs_session_init+0x1e1/0x1410 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x7f/0x269 fs/super.c:1237 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x36b/0x26a0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb8/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x459829 RSP: 002b:00007ff945e1fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007ff945e206d4 R13: 00000000004c5dcf R14: 00000000004da870 R15: 00000000ffffffff INFO: task syz-executor.1:7144 blocked for more than 140 seconds. Not tainted 4.14.184-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D27608 7144 6242 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x6e8/0xcc0 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x263/0x440 kernel/sched/completion.c:144 flush_work+0x38b/0x720 kernel/workqueue.c:2893 __cancel_work_timer+0x286/0x420 kernel/workqueue.c:2964 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3000 p9_conn_destroy net/9p/trans_fd.c:873 [inline] p9_fd_close+0x26f/0x410 net/9p/trans_fd.c:899 p9_client_create+0x99b/0xf40 net/9p/client.c:1095 v9fs_session_init+0x1e1/0x1410 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x7f/0x269 fs/super.c:1237 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x36b/0x26a0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb8/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x459829 RSP: 002b:00007f957398dc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007f957398e6d4 R13: 00000000004c5dcf R14: 00000000004da870 R15: 00000000ffffffff INFO: task syz-executor.2:7149 blocked for more than 140 seconds. Not tainted 4.14.184-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27144 7149 6240 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x6e8/0xcc0 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x263/0x440 kernel/sched/completion.c:144 flush_work+0x38b/0x720 kernel/workqueue.c:2893 __cancel_work_timer+0x286/0x420 kernel/workqueue.c:2964 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3000 p9_conn_destroy net/9p/trans_fd.c:873 [inline] p9_fd_close+0x26f/0x410 net/9p/trans_fd.c:899 p9_client_create+0x99b/0xf40 net/9p/client.c:1095 v9fs_session_init+0x1e1/0x1410 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x7f/0x269 fs/super.c:1237 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x36b/0x26a0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb8/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x459829 RSP: 002b:00007f77b67afc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007f77b67b06d4 R13: 00000000004c5dcf R14: 00000000004da870 R15: 00000000ffffffff INFO: task syz-executor.5:7162 blocked for more than 140 seconds. Not tainted 4.14.184-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D27608 7162 6244 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x6e8/0xcc0 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x263/0x440 kernel/sched/completion.c:144 flush_work+0x38b/0x720 kernel/workqueue.c:2893 __cancel_work_timer+0x286/0x420 kernel/workqueue.c:2964 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3000 p9_conn_destroy net/9p/trans_fd.c:873 [inline] p9_fd_close+0x26f/0x410 net/9p/trans_fd.c:899 p9_client_create+0x99b/0xf40 net/9p/client.c:1095 v9fs_session_init+0x1e1/0x1410 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x7f/0x269 fs/super.c:1237 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x36b/0x26a0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb8/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x459829 RSP: 002b:00007fcb8ae70c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007fcb8ae716d4 R13: 00000000004c5dcf R14: 00000000004da870 R15: 00000000ffffffff INFO: task syz-executor.3:7180 blocked for more than 140 seconds. Not tainted 4.14.184-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D27608 7180 6246 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x6e8/0xcc0 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x263/0x440 kernel/sched/completion.c:144 flush_work+0x38b/0x720 kernel/workqueue.c:2893 __cancel_work_timer+0x286/0x420 kernel/workqueue.c:2964 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3000 p9_conn_destroy net/9p/trans_fd.c:873 [inline] p9_fd_close+0x26f/0x410 net/9p/trans_fd.c:899 p9_client_create+0x99b/0xf40 net/9p/client.c:1095 v9fs_session_init+0x1e1/0x1410 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x7f/0x269 fs/super.c:1237 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x36b/0x26a0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb8/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x459829 RSP: 002b:00007fd0d23c4c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007fd0d23c56d4 R13: 00000000004c5dcf R14: 00000000004da870 R15: 00000000ffffffff INFO: task syz-executor.4:7184 blocked for more than 140 seconds. Not tainted 4.14.184-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27256 7184 6247 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x780/0x1d20 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x6e8/0xcc0 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x263/0x440 kernel/sched/completion.c:144 flush_work+0x38b/0x720 kernel/workqueue.c:2893 __cancel_work_timer+0x286/0x420 kernel/workqueue.c:2964 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3000 p9_conn_destroy net/9p/trans_fd.c:873 [inline] p9_fd_close+0x26f/0x410 net/9p/trans_fd.c:899 p9_client_create+0x99b/0xf40 net/9p/client.c:1095 v9fs_session_init+0x1e1/0x1410 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x7f/0x269 fs/super.c:1237 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x36b/0x26a0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb8/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x459829 RSP: 002b:00007fbaf974fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829 RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 00007fbaf97506d4 R13: 00000000004c5dcf R14: 00000000004da870 R15: 00000000ffffffff Showing all locks held in the system: 2 locks held by kworker/1:1/23: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 2 locks held by kworker/0:1/24: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 1 lock held by khungtaskd/1016: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4548 2 locks held by kworker/0:2/3234: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 2 locks held by kworker/0:3/6668: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 2 locks held by kworker/0:4/6797: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 2 locks held by kworker/0:5/7069: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1016 Comm: khungtaskd Not tainted 4.14.184-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+0xf7/0x13b lib/dump_stack.c:58 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:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x522/0xb40 kernel/hung_task.c:274 kthread+0x338/0x400 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: 22 Comm: kworker/u4:1 Not tainted 4.14.184-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker task: ffff8880a9e3c5c0 task.stack: ffff8880a9e48000 RIP: 0010:debug_lockdep_rcu_enabled.part.3+0xb/0x60 kernel/rcu/update.c:297 RSP: 0018:ffff8880a9e4fc20 EFLAGS: 00000002 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000004 RSI: 0000000000000000 RDI: ffffffff87cb51c0 RBP: ffff8880a9e4fc30 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000050 R11: ffff8880a9e3c5c0 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0f2b58a010 CR3: 0000000092290000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_lock_acquire include/trace/events/lock.h:13 [inline] lock_acquire+0x312/0x400 kernel/locking/lockdep.c:3997 rcu_lock_acquire include/linux/rcupdate.h:242 [inline] rcu_read_lock include/linux/rcupdate.h:629 [inline] batadv_nc_process_nc_paths.part.15+0xc3/0x2d0 net/batman-adv/network-coding.c:695 batadv_nc_process_nc_paths net/batman-adv/network-coding.c:687 [inline] batadv_nc_worker+0x440/0x630 net/batman-adv/network-coding.c:735 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Code: 45 a0 e8 19 c5 37 00 48 8b 45 a0 e9 bc fd ff ff 48 8b 7d d0 e8 07 c5 37 00 e9 95 fd ff ff 66 90 48 b8 00 00 00 00 00 fc ff df 55 <48> 89 e5 53 65 48 8b 1c 25 40 ee 01 00 48 8d bb 84 08 00 00 48