bisecting fixing commit since eb575cd5d7f60241d016fdd13a9e86d962093c9b building syzkaller on 9d2ab5dfe7727dfea4b9b279f4edf731acb386ef testing commit eb575cd5d7f60241d016fdd13a9e86d962093c9b compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 423eca495bd4b38969c3c103b470910f6f7b887da5c16829b1482299d024bd51 all runs: crashed: INFO: task hung in ext4_fill_super testing current HEAD 2950c9c5e0df6bd34af45a5168bbee345e95eae2 testing commit 2950c9c5e0df6bd34af45a5168bbee345e95eae2 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: a404f61201ace070d5451fdd2efef467ccea93e1429b70190924180624912910 all runs: crashed: INFO: task hung in ext4_fill_super revisions tested: 2, total time: 28m36.707596834s (build: 16m15.125600543s, test: 11m56.316775296s) the crash still happens on HEAD commit msg: Linux 4.19.207 crash: INFO: task hung in ext4_fill_super Bluetooth: hci2: command 0x0406 tx timeout Bluetooth: hci0: command 0x0406 tx timeout Bluetooth: hci5: command 0x0406 tx timeout ieee802154 phy0 wpan0: encryption failed: -22 ieee802154 phy1 wpan1: encryption failed: -22 INFO: task syz-executor.5:9978 blocked for more than 140 seconds. Not tainted 4.19.207-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D27432 9978 8483 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x6f6/0xd20 kernel/time/timer.c:1794 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x4c0 kernel/kthread.c:588 ext4_fill_super+0x6991/0xb570 fs/ext4/super.c:4646 mount_bdev+0x26f/0x330 fs/super.c:1158 ext4_mount+0x10/0x20 fs/ext4/super.c:6054 mount_fs+0x7f/0x2b0 fs/super.c:1261 vfs_kern_mount.part.11+0x58/0x3d0 fs/namespace.c:961 vfs_kern_mount fs/namespace.c:951 [inline] do_new_mount fs/namespace.c:2492 [inline] do_mount+0x376/0x2630 fs/namespace.c:2822 ksys_mount+0xb1/0xd0 fs/namespace.c:3038 __do_sys_mount fs/namespace.c:3052 [inline] __se_sys_mount fs/namespace.c:3049 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3049 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: Bad RIP value. RSP: 002b:00007f5367accfa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f5367acd000 RBP: 00007f5367acd040 R08: 00007f5367acd040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007f5367acd000 R15: 0000000020000200 INFO: task syz-executor.2:9989 blocked for more than 140 seconds. Not tainted 4.19.207-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27432 9989 8476 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x6f6/0xd20 kernel/time/timer.c:1794 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x4c0 kernel/kthread.c:588 ext4_fill_super+0x6991/0xb570 fs/ext4/super.c:4646 mount_bdev+0x26f/0x330 fs/super.c:1158 ext4_mount+0x10/0x20 fs/ext4/super.c:6054 mount_fs+0x7f/0x2b0 fs/super.c:1261 vfs_kern_mount.part.11+0x58/0x3d0 fs/namespace.c:961 vfs_kern_mount fs/namespace.c:951 [inline] do_new_mount fs/namespace.c:2492 [inline] do_mount+0x376/0x2630 fs/namespace.c:2822 ksys_mount+0xb1/0xd0 fs/namespace.c:3038 __do_sys_mount fs/namespace.c:3052 [inline] __se_sys_mount fs/namespace.c:3049 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3049 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: Bad RIP value. RSP: 002b:00007f224df47fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f224df48000 RBP: 00007f224df48040 R08: 00007f224df48040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007f224df48000 R15: 0000000020000200 INFO: task syz-executor.4:10036 blocked for more than 140 seconds. Not tainted 4.19.207-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27432 10036 8479 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x6f6/0xd20 kernel/time/timer.c:1794 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136 kthread_stop+0xc9/0x4c0 kernel/kthread.c:588 ext4_fill_super+0x6991/0xb570 fs/ext4/super.c:4646 mount_bdev+0x26f/0x330 fs/super.c:1158 ext4_mount+0x10/0x20 fs/ext4/super.c:6054 mount_fs+0x7f/0x2b0 fs/super.c:1261 vfs_kern_mount.part.11+0x58/0x3d0 fs/namespace.c:961 vfs_kern_mount fs/namespace.c:951 [inline] do_new_mount fs/namespace.c:2492 [inline] do_mount+0x376/0x2630 fs/namespace.c:2822 ksys_mount+0xb1/0xd0 fs/namespace.c:3038 __do_sys_mount fs/namespace.c:3052 [inline] __se_sys_mount fs/namespace.c:3049 [inline] __x64_sys_mount+0xb9/0x150 fs/namespace.c:3049 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467afa Code: Bad RIP value. RSP: 002b:00007f445f5e9fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f445f5ea000 RBP: 00007f445f5ea040 R08: 00007f445f5ea040 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 00007f445f5ea000 R15: 0000000020000200 Showing all locks held in the system: 3 locks held by kworker/u4:2/28: #0: 00000000ecbcd1b3 (&rq->lock){-.-.}, at: idle_balance kernel/sched/fair.c:9702 [inline] #0: 00000000ecbcd1b3 (&rq->lock){-.-.}, at: pick_next_task_fair+0x1006/0x1540 kernel/sched/fair.c:6841 #1: 000000007084363c (rcu_read_lock){....}, at: cpu_of kernel/sched/sched.h:923 [inline] #1: 000000007084363c (rcu_read_lock){....}, at: __update_idle_core+0x3c/0x3f0 kernel/sched/fair.c:6057 #2: 0000000036ea874b (&base->lock){-.-.}, at: lock_timer_base+0xc8/0x160 kernel/time/timer.c:950 1 lock held by khungtaskd/1571: #0: 000000007084363c (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4443 1 lock held by systemd-journal/4691: #0: 00000000ecbcd1b3 (&rq->lock){-.-.}, at: idle_balance kernel/sched/fair.c:9702 [inline] #0: 00000000ecbcd1b3 (&rq->lock){-.-.}, at: pick_next_task_fair+0x1006/0x1540 kernel/sched/fair.c:6841 1 lock held by in:imklog/7798: 1 lock held by syz-executor.5/9978: #0: 0000000098cd36f0 (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:226 [inline] #0: 0000000098cd36f0 (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb70 fs/super.c:519 1 lock held by syz-executor.2/9989: #0: 000000006dee70b2 (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:226 [inline] #0: 000000006dee70b2 (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb70 fs/super.c:519 1 lock held by syz-executor.4/10036: #0: 000000001568fb0f (&type->s_umount_key#25/1){+.+.}, at: alloc_super fs/super.c:226 [inline] #0: 000000001568fb0f (&type->s_umount_key#25/1){+.+.}, at: sget_userns+0x1a1/0xb70 fs/super.c:519 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1571 Comm: khungtaskd Not tainted 4.19.207-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+0x17c/0x226 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf6/0x120 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+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60