bisecting fixing commit since 78d697fc93f98054e36a3ab76dca1a88802ba7be building syzkaller on c88c7b75a4e022b758f4b0f1bf3db8ebb2fb25e6 testing commit 78d697fc93f98054e36a3ab76dca1a88802ba7be with gcc (GCC) 8.1.0 kernel signature: 76205d6e5b832df4ca3f01635ad1e59d4cee94845542d04806f81be29144bd31 run #0: crashed: INFO: task hung in lo_open run #1: crashed: INFO: task hung in lo_release run #2: crashed: INFO: task hung in blkdev_put run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing current HEAD a41ba30d9df20fe141c92aacbb56b6b077f19716 testing commit a41ba30d9df20fe141c92aacbb56b6b077f19716 with gcc (GCC) 8.1.0 kernel signature: 274065da56c211f55ff44fffc819bd1106bcd6800d5ad7c7edee5831c2d99643 run #0: crashed: INFO: task hung in lo_open run #1: crashed: INFO: task hung in lo_open run #2: crashed: INFO: task hung in lo_open run #3: crashed: INFO: task hung in lo_open run #4: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor931772595" "root@10.128.15.211:./syz-executor931772595"]: exit status 1 ssh: connect to host 10.128.15.211 port 22: Connection timed out lost connection run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 39m8.353405942s (build: 16m36.051079486s, test: 21m55.914258598s) the crash still happens on HEAD commit msg: Linux 4.14.181 crash: INFO: task hung in lo_open NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task syz-executor.4:6471 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D24888 6471 1 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_open+0x16/0xa0 drivers/block/loop.c:1634 __blkdev_get+0x2a4/0x1030 fs/block_dev.c:1472 blkdev_get+0x26d/0x860 fs/block_dev.c:1612 blkdev_open+0x19f/0x200 fs/block_dev.c:1770 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3bd0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4161f0 RSP: 002b:00007ffd16efc418 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004161f0 RDX: 00007ffd16efc4aa RSI: 0000000000000002 RDI: 00007ffd16efc4a0 RBP: 000000000071b460 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd16efc450 R14: 0000000000000003 R15: 00007ffd16efc460 INFO: task syz-executor.5:6472 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D24832 6472 1 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_open+0x16/0xa0 drivers/block/loop.c:1634 __blkdev_get+0x2a4/0x1030 fs/block_dev.c:1472 blkdev_get+0x26d/0x860 fs/block_dev.c:1612 blkdev_open+0x19f/0x200 fs/block_dev.c:1770 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3bd0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4161f0 RSP: 002b:00007fff9c2a6dd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004161f0 RDX: 00007fff9c2a6e6a RSI: 0000000000000002 RDI: 00007fff9c2a6e60 RBP: 000000000071b460 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff9c2a6e10 R14: 0000000000000003 R15: 00007fff9c2a6e20 INFO: task systemd-udevd:7771 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. systemd-udevd D27792 7771 3634 0x00000104 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_open+0x16/0xa0 drivers/block/loop.c:1634 __blkdev_get+0x9e4/0x1030 fs/block_dev.c:1537 blkdev_get+0x26d/0x860 fs/block_dev.c:1612 blkdev_open+0x19f/0x200 fs/block_dev.c:1770 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3bd0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fdf26815840 RSP: 002b:00007fffe26d7948 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000560a333ce7d0 RCX: 00007fdf26815840 RDX: 0000560a327cefe3 RSI: 0000000000080000 RDI: 0000560a333cc170 RBP: 0000000000000001 R08: 0000560a327ce670 R09: 0000000000000110 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000560a333cbf40 R15: 00000000ffffffff INFO: task systemd-udevd:7779 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. systemd-udevd D26976 7779 3634 0x00000104 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_release+0x1a/0x180 drivers/block/loop.c:1677 __blkdev_put+0x406/0x730 fs/block_dev.c:1791 blkdev_put+0x73/0x480 fs/block_dev.c:1856 blkdev_close+0x88/0xd0 fs/block_dev.c:1863 __fput+0x232/0x750 fs/file_table.c:210 ____fput+0x9/0x10 fs/file_table.c:244 task_work_run+0xe5/0x170 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x16a/0x1b0 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+0x416/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fdf26815270 RSP: 002b:00007fffe26dcd48 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fdf26815270 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007fdf276ce710 R08: 0000560a333cbde0 R09: 0000560a333cbb00 R10: 00007fdf276ce8c0 R11: 0000000000000246 R12: 0000000000000000 R13: 0000560a333d5e40 R14: 0000000000000003 R15: 000000000000000e INFO: task syz-executor.0:7790 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28936 7790 6465 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 blkdev_reread_part+0x18/0x40 block/ioctl.c:192 loop_reread_partitions+0x5d/0x70 drivers/block/loop.c:624 loop_set_status+0xb04/0x1070 drivers/block/loop.c:1193 loop_set_status64+0x83/0xc0 drivers/block/loop.c:1311 lo_ioctl+0x547/0x1c70 drivers/block/loop.c:1441 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x784/0x16b0 block/ioctl.c:594 block_ioctl+0xd7/0x130 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45c2e7 RSP: 002b:00007fa03cd029d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045c2e7 RDX: 00007fa03cd02ac0 RSI: 0000000000004c04 RDI: 0000000000000004 RBP: 000000000076bf20 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000202 R12: 00000000ffffffff R13: 0000000000000c1c R14: 00000000004c138b R15: 000000000076bf2c INFO: task syz-executor.0:7793 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D29232 7793 6465 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 loop_control_ioctl+0xf6/0x2b0 drivers/block/loop.c:2007 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45c479 RSP: 002b:00007fa03cce1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fa03cce26d4 RCX: 000000000045c479 RDX: 9999999999999999 RSI: 0000000000004c81 RDI: 0000000000000006 RBP: 000000000076bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000006b5 R14: 00000000004c9318 R15: 000000000076bfcc INFO: task syz-executor.0:7815 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28184 7815 6465 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 blkdev_get+0x26d/0x860 fs/block_dev.c:1612 blkdev_open+0x19f/0x200 fs/block_dev.c:1770 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3bd0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x416211 RSP: 002b:00007fa03ccc09d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007fa03ccc16d4 RCX: 0000000000416211 RDX: 00007fa03ccc0bba RSI: 0000000000000002 RDI: 00007fa03ccc0bb0 RBP: 000000000076c060 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000293 R12: 00000000ffffffff R13: 0000000000000c1c R14: 00000000004c138b R15: 000000000076c06c INFO: task syz-executor.1:7789 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28920 7789 6464 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 blkdev_reread_part+0x18/0x40 block/ioctl.c:192 loop_reread_partitions+0x5d/0x70 drivers/block/loop.c:624 loop_set_status+0xb04/0x1070 drivers/block/loop.c:1193 loop_set_status64+0x83/0xc0 drivers/block/loop.c:1311 lo_ioctl+0x547/0x1c70 drivers/block/loop.c:1441 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x784/0x16b0 block/ioctl.c:594 block_ioctl+0xd7/0x130 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45c2e7 RSP: 002b:00007f3592f279d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045c2e7 RDX: 00007f3592f27ac0 RSI: 0000000000004c04 RDI: 0000000000000004 RBP: 000000000076bf20 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000202 R12: 00000000ffffffff R13: 0000000000000c1c R14: 00000000004c138b R15: 000000000076bf2c INFO: task syz-executor.1:7792 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29608 7792 6464 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 loop_control_ioctl+0x6d/0x2b0 drivers/block/loop.c:1993 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x180/0xfb0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x74/0x80 fs/ioctl.c:692 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45c479 RSP: 002b:00007f3592f06c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3592f076d4 RCX: 000000000045c479 RDX: 9999999999999999 RSI: 0000000000004c81 RDI: 0000000000000006 RBP: 000000000076bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000006b5 R14: 00000000004c9318 R15: 000000000076bfcc INFO: task syz-executor.1:7814 blocked for more than 140 seconds. Not tainted 4.14.181-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28184 7814 6464 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xabc/0x14c0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 blkdev_get+0x26d/0x860 fs/block_dev.c:1612 blkdev_open+0x19f/0x200 fs/block_dev.c:1770 do_dentry_open+0x620/0xdb0 fs/open.c:777 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xdde/0x3bd0 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1c2/0x340 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x416211 RSP: 002b:00007f3592ee59d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007f3592ee66d4 RCX: 0000000000416211 RDX: 00007f3592ee5bba RSI: 0000000000000002 RDI: 00007f3592ee5bb0 RBP: 000000000076c060 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000293 R12: 00000000ffffffff R13: 0000000000000c1c R14: 00000000004c138b R15: 000000000076c06c Showing all locks held in the system: 1 lock held by khungtaskd/1056: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4548 1 lock held by in:imklog/5966: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x8e/0xc0 fs/file.c:769 2 locks held by syz-executor.4/6471: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 #1: (loop_index_mutex){+.+.}, at: [] lo_open+0x16/0xa0 drivers/block/loop.c:1634 2 locks held by syz-executor.5/6472: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 #1: (loop_index_mutex){+.+.}, at: [] lo_open+0x16/0xa0 drivers/block/loop.c:1634 2 locks held by systemd-udevd/7771: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 #1: (loop_index_mutex){+.+.}, at: [] lo_open+0x16/0xa0 drivers/block/loop.c:1634 2 locks held by systemd-udevd/7779: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_put+0xa5/0x730 fs/block_dev.c:1778 #1: (loop_index_mutex){+.+.}, at: [] lo_release+0x1a/0x180 drivers/block/loop.c:1677 2 locks held by syz-executor.0/7790: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x8a/0x1c70 drivers/block/loop.c:1414 #1: (&bdev->bd_mutex){+.+.}, at: [] blkdev_reread_part+0x18/0x40 block/ioctl.c:192 2 locks held by syz-executor.0/7793: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x6d/0x2b0 drivers/block/loop.c:1993 #1: (&lo->lo_ctl_mutex){+.+.}, at: [] loop_control_ioctl+0xf6/0x2b0 drivers/block/loop.c:2007 1 lock held by syz-executor.0/7815: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 2 locks held by syz-executor.1/7789: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [] lo_ioctl+0x8a/0x1c70 drivers/block/loop.c:1414 #1: (&bdev->bd_mutex){+.+.}, at: [] blkdev_reread_part+0x18/0x40 block/ioctl.c:192 1 lock held by syz-executor.1/7792: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x6d/0x2b0 drivers/block/loop.c:1993 1 lock held by syz-executor.1/7814: #0: (&bdev->bd_mutex){+.+.}, at: [] __blkdev_get+0x133/0x1030 fs/block_dev.c:1457 1 lock held by syz-executor.2/7888: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x6d/0x2b0 drivers/block/loop.c:1993 1 lock held by syz-executor.3/7890: #0: (loop_index_mutex){+.+.}, at: [] loop_control_ioctl+0x6d/0x2b0 drivers/block/loop.c:1993 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1056 Comm: khungtaskd Not tainted 4.14.181-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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.181-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker task: ffff8880a9cd2140 task.stack: ffff8880a9cd8000 RIP: 0010:__lock_acquire+0x3c9/0x4500 kernel/locking/lockdep.c:3435 RSP: 0018:ffff8880a9cdfa20 EFLAGS: 00000046 RAX: ffff8880a9cd2a30 RBX: 00000000000006d0 RCX: 0000000000000000 RDX: ffff8880a9cd2a30 RSI: 00000000000006d0 RDI: ffff8880a9cd2a28 RBP: ffff8880a9cdfbf0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000050 R11: ffff8880a9cd2140 R12: ffff88809a1cd980 R13: 0000000000000000 R14: 0000000000000002 R15: ffff8880a9cd2a18 FS: 0000000000000000(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f769ec3d010 CR3: 000000008ba96000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x173/0x400 kernel/locking/lockdep.c:3998 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:176 spin_lock_bh include/linux/spinlock.h:322 [inline] batadv_nc_purge_paths+0xc0/0x310 net/batman-adv/network-coding.c:450 batadv_nc_worker+0x1f6/0x630 net/batman-adv/network-coding.c:727 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: c1 ea 03 49 89 47 08 48 b8 00 00 00 00 00 fc ff df 80 3c 02 00 0f 85 7f 2d 00 00 49 8d 47 18 4d 89 67 10 48 89 c2 48 89 44 24 70 <48> b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 8d