bisecting fixing commit since ddef1e8e3f6eb26034833b7255e3fa584d54a230 building syzkaller on 5ea87a6638e52a94361b26b8576a1605585815fb testing commit ddef1e8e3f6eb26034833b7255e3fa584d54a230 with gcc (GCC) 8.1.0 kernel signature: 60f16f8bd66c192166a7fc20c182d825e6efc6288ce963217fa94622c706cc66 run #0: crashed: INFO: task hung in mount_bdev run #1: crashed: INFO: task hung in grab_super run #2: crashed: INFO: task hung in grab_super run #3: crashed: INFO: task hung in mount_bdev run #4: crashed: INFO: task hung in grab_super run #5: crashed: INFO: task hung in grab_super run #6: crashed: INFO: task hung in grab_super run #7: OK run #8: crashed: INFO: task hung in grab_super run #9: crashed: INFO: task hung in grab_super testing current HEAD bae31eef2a167ef160ab2703b6a2f5bbecd98d92 testing commit bae31eef2a167ef160ab2703b6a2f5bbecd98d92 with gcc (GCC) 8.1.0 kernel signature: bbd464f5580048a8a06ec27cfd2f63f22e80c3a8602d08f2262699a936a85ed9 run #0: crashed: INFO: task hung in grab_super run #1: crashed: INFO: task hung in mount_bdev run #2: crashed: INFO: task hung in mount_bdev run #3: crashed: INFO: task hung in grab_super run #4: crashed: INFO: task hung in grab_super run #5: crashed: INFO: task hung in grab_super run #6: crashed: INFO: task hung in grab_super run #7: crashed: INFO: task hung in grab_super run #8: crashed: INFO: task hung in grab_super run #9: crashed: INFO: task hung in grab_super revisions tested: 2, total time: 41m37.901377962s (build: 16m56.049355183s, test: 23m31.572653819s) the crash still happens on HEAD commit msg: Linux 4.14.200 crash: INFO: task hung in grab_super UDF-fs: Scanning with blocksize 2048 failed UDF-fs: warning (device loop0): udf_load_vrs: No VRS found UDF-fs: Scanning with blocksize 4096 failed print_req_error: I/O error, dev loop0, sector 64 INFO: task syz-executor.4:18151 blocked for more than 140 seconds. Not tainted 4.14.200-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D28488 18151 6253 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 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline] rwsem_down_write_failed+0x54f/0xb50 kernel/locking/rwsem-xadd.c:617 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105 __down_write arch/x86/include/asm/rwsem.h:126 [inline] down_write+0x53/0x90 kernel/locking/rwsem.c:56 grab_super+0x56/0x130 fs/super.c:373 sget_userns+0x687/0xb40 fs/super.c:504 sget+0xbe/0x100 fs/super.c:572 mount_bdev+0xc9/0x330 fs/super.c:1107 udf_mount+0x10/0x20 fs/udf/super.c:132 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: 0033:0x459fc9 RSP: 002b:00007fdb3879cc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459fc9 RDX: 0000000020000040 RSI: 0000000020000240 RDI: 00000000200000c0 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdb3879d6d4 R13: 00000000004c6a32 R14: 00000000004dbe98 R15: 00000000ffffffff INFO: task syz-executor.5:18155 blocked for more than 140 seconds. Not tainted 4.14.200-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28488 18155 6256 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 mount_bdev+0x71/0x330 fs/super.c:1101 udf_mount+0x10/0x20 fs/udf/super.c:132 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: 0033:0x459fc9 RSP: 002b:00007f87e4c7fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459fc9 RDX: 0000000020000040 RSI: 0000000020000240 RDI: 00000000200000c0 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f87e4c806d4 R13: 00000000004c6a32 R14: 00000000004dbe98 R15: 00000000ffffffff INFO: task syz-executor.0:18156 blocked for more than 140 seconds. Not tainted 4.14.200-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28488 18156 6255 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 mount_bdev+0x71/0x330 fs/super.c:1101 udf_mount+0x10/0x20 fs/udf/super.c:132 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: 0033:0x459fc9 RSP: 002b:00007f0373df8c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459fc9 RDX: 0000000020000040 RSI: 0000000020000240 RDI: 00000000200000c0 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0373df96d4 R13: 00000000004c6a32 R14: 00000000004dbe98 R15: 00000000ffffffff INFO: task syz-executor.3:18166 blocked for more than 140 seconds. Not tainted 4.14.200-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28488 18166 6251 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 mount_bdev+0x71/0x330 fs/super.c:1101 udf_mount+0x10/0x20 fs/udf/super.c:132 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: 0033:0x459fc9 RSP: 002b:00007f11aec42c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459fc9 RDX: 0000000020000040 RSI: 0000000020000240 RDI: 00000000200000c0 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f11aec436d4 R13: 00000000004c6a32 R14: 00000000004dbe98 R15: 00000000ffffffff INFO: task syz-executor.1:18179 blocked for more than 140 seconds. Not tainted 4.14.200-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28488 18179 6249 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 mount_bdev+0x71/0x330 fs/super.c:1101 udf_mount+0x10/0x20 fs/udf/super.c:132 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: 0033:0x459fc9 RSP: 002b:00007fa18c0a6c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459fc9 RDX: 0000000020000040 RSI: 0000000020000240 RDI: 00000000200000c0 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa18c0a76d4 R13: 00000000004c6a32 R14: 00000000004dbe98 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/1019: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4548 2 locks held by syz-executor.4/18151: #0: (&bdev->bd_fsfreeze_mutex){+.+.}, at: [] mount_bdev+0x71/0x330 fs/super.c:1101 #1: (&type->s_umount_key#59){+.+.}, at: [] grab_super+0x56/0x130 fs/super.c:373 1 lock held by syz-executor.5/18155: #0: (&bdev->bd_fsfreeze_mutex){+.+.}, at: [] mount_bdev+0x71/0x330 fs/super.c:1101 1 lock held by syz-executor.0/18156: #0: (&bdev->bd_fsfreeze_mutex){+.+.}, at: [] mount_bdev+0x71/0x330 fs/super.c:1101 1 lock held by syz-executor.3/18166: #0: (&bdev->bd_fsfreeze_mutex){+.+.}, at: [] mount_bdev+0x71/0x330 fs/super.c:1101 1 lock held by syz-executor.1/18179: #0: (&bdev->bd_fsfreeze_mutex){+.+.}, at: [] mount_bdev+0x71/0x330 fs/super.c:1101 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1019 Comm: khungtaskd Not tainted 4.14.200-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: 2314 Comm: kworker/u4:4 Not tainted 4.14.200-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_purge_orig task: ffff8880a193e500 task.stack: ffff8880a1fd8000 RIP: 0010:should_resched arch/x86/include/asm/preempt.h:99 [inline] RIP: 0010:__local_bh_enable_ip+0xd3/0x180 kernel/softirq.c:192 RSP: 0018:ffff8880a1fdfc70 EFLAGS: 00000282 RAX: dffffc0000000000 RBX: 0000000000000201 RCX: 1ffff11014327dba RDX: 1ffffffff0f22dc3 RSI: ffff8880a193edb0 RDI: ffffffff87916e18 RBP: ffff8880a1fdfc80 R08: ffff8880a193edd0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8609b028 R13: dffffc0000000000 R14: ffff88809b0f1000 R15: ffff888095525438 FS: 0000000000000000(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f45795f1000 CR3: 0000000094f26000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline] _raw_spin_unlock_bh+0x30/0x40 kernel/locking/spinlock.c:208 spin_unlock_bh include/linux/spinlock.h:362 [inline] _batadv_purge_orig+0x5b8/0xe80 net/batman-adv/originator.c:1325 batadv_purge_orig+0x14/0x60 net/batman-adv/originator.c:1338 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: 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 b1 00 00 00 48 83 3d 72 6f 59 06 00 0f 84 95 00 00 00 fb 66 0f 1f 44 00 00 <65> 8b 05 16 ef c9 7e 85 c0 75 05 e8 66 40 c8 ff 5b 41 5c 5d c3