bisecting fixing commit since c98875d930e915d01e8c40c7d3c16f00b3c8abe1 building syzkaller on b0e8efcb4b0aac61f4647a76bbe54a5d38a370ba testing commit c98875d930e915d01e8c40c7d3c16f00b3c8abe1 with gcc (GCC) 8.1.0 kernel signature: 1056919cc19f983474743343a88ad7eed342de2d5b2fb316cb5665c782524089 all runs: crashed: INFO: task hung in p9_fd_close testing current HEAD 6dd0e32665e591e9debe3edaf73c2f8135bf047e testing commit 6dd0e32665e591e9debe3edaf73c2f8135bf047e with gcc (GCC) 8.1.0 kernel signature: 23c80a60b51064c4a36a9c4b663a2050d6e3b8946eb33d7869f123c489687692 all runs: crashed: INFO: task hung in p9_fd_close revisions tested: 2, total time: 29m3.859687198s (build: 16m59.403976118s, test: 11m22.21597761s) the crash still happens on HEAD commit msg: Linux 4.19.115 crash: INFO: task hung in p9_fd_close IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 8021q: adding VLAN 0 to HW filter on device batadv0 INFO: task syz-executor.3:7255 blocked for more than 140 seconds. Not tainted 4.19.115-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D27912 7255 6231 0x00000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x792/0x1c20 kernel/sched/core.c:3515 schedule+0x7f/0x1b0 kernel/sched/core.c:3559 schedule_timeout+0x6d7/0xda0 kernel/time/timer.c:1782 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x282/0x460 kernel/sched/completion.c:136 __flush_work+0x3d5/0x7f0 kernel/workqueue.c:2928 __cancel_work_timer+0x2f1/0x430 kernel/workqueue.c:3015 cancel_work_sync+0xb/0x10 kernel/workqueue.c:3051 p9_conn_destroy net/9p/trans_fd.c:878 [inline] p9_fd_close+0x267/0x4e0 net/9p/trans_fd.c:913 p9_client_create+0x8f1/0x10f0 net/9p/client.c:1084 v9fs_session_init+0x1ed/0x14c0 fs/9p/v9fs.c:421 v9fs_mount+0x73/0x770 fs/9p/vfs_super.c:135 mount_fs+0x84/0x2a7 fs/super.c:1261 vfs_kern_mount.part.34+0x58/0x3d0 fs/namespace.c:961 vfs_kern_mount fs/namespace.c:951 [inline] do_new_mount fs/namespace.c:2469 [inline] do_mount+0x36e/0x2410 fs/namespace.c:2799 ksys_mount+0xba/0xe0 fs/namespace.c:3015 __do_sys_mount fs/namespace.c:3029 [inline] __se_sys_mount fs/namespace.c:3026 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3026 do_syscall_64+0xd6/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458c29 Code: Bad RIP value. RSP: 002b:00007f191ec96c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458c29 RDX: 0000000020000100 RSI: 00000000200000c0 RDI: 0000000000000000 RBP: 000000000073bf00 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f191ec976d4 R13: 00000000004c4c14 R14: 00000000004d88a0 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1037: #0: 0000000009b8d969 (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4438 2 locks held by kworker/0:2/2752: #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline] #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000472a5581 ((wq_completion)"events"){+.+.}, at: process_one_work+0x762/0x1670 kernel/workqueue.c:2126 #1: 0000000081a8fb70 ((work_completion)(&m->rq)){+.+.}, at: process_one_work+0x792/0x1670 kernel/workqueue.c:2130 1 lock held by in:imklog/5670: #0: 00000000a8e35867 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1037 Comm: khungtaskd Not tainted 4.19.115-syzkaller #0 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+0x123/0x177 lib/dump_stack.c:118 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x327/0x3f0 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3514 Comm: systemd-journal Not tainted 4.19.115-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:qlink_to_object mm/kasan/quarantine.c:136 [inline] RIP: 0010:qlink_free mm/kasan/quarantine.c:141 [inline] RIP: 0010:qlist_free_all+0x41/0x140 mm/kasan/quarantine.c:166 Code: 0f 84 b7 00 00 00 49 89 f4 48 89 7d c8 49 c7 c7 80 09 12 88 4d 85 e4 4d 89 e5 0f 84 c8 00 00 00 49 63 85 fc 00 00 00 4c 8b 33 <48> 29 c3 49 83 3f 00 0f 84 e6 00 00 00 9c 58 0f 1f 44 00 00 48 83 RSP: 0018:ffff8880944dfca8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff888093e267c0 RCX: ffffea00024c18c7 RDX: 0000000000000000 RSI: ffff8880944d69c0 RDI: ffffffff88d2b929 RBP: ffff8880944dfce0 R08: 1ffff11012a9c600 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880aa44d540 R14: ffff888095043a00 R15: ffffffff88120980 FS: 00007fd067a9e8c0(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd064e63000 CR3: 0000000094a79000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: quarantine_reduce+0x163/0x1a0 mm/kasan/quarantine.c:259 kasan_kmalloc+0x9b/0xe0 mm/kasan/kasan.c:538 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc mm/slab.c:3397 [inline] kmem_cache_alloc+0x11b/0x730 mm/slab.c:3557 getname_flags+0xb8/0x520 fs/namei.c:140 getname fs/namei.c:211 [inline] user_path_create fs/namei.c:3696 [inline] do_mkdirat+0x9a/0x220 fs/namei.c:3834 __do_sys_mkdir fs/namei.c:3858 [inline] __se_sys_mkdir fs/namei.c:3856 [inline] __x64_sys_mkdir+0x57/0x80 fs/namei.c:3856 do_syscall_64+0xd6/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fd066d5a687 Code: 00 b8 ff ff ff ff c3 0f 1f 40 00 48 8b 05 09 d8 2b 00 64 c7 00 5f 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 b8 53 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 d7 2b 00 f7 d8 64 89 01 48 RSP: 002b:00007ffd9d4ff3d8 EFLAGS: 00000293 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: 00007ffd9d502440 RCX: 00007fd066d5a687 RDX: 0000000000000000 RSI: 00000000000001ed RDI: 000055b674f128c0 RBP: 00007ffd9d4ff410 R08: 000055b6731a03e5 R09: 0000000000000018 R10: 0000000000000069 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000001 R14: 000055b674f128c0 R15: 00007ffd9d4ffa50