bisecting fixing commit since 675cc038067f0e530471c56a7442935f84669d95 building syzkaller on 65a7a8540d29e72622fca06522587f7e66539fd3 testing commit 675cc038067f0e530471c56a7442935f84669d95 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: acbd349eace2012ba35336dee9e559bdf96c35164e6e96e50e22e706bf82404b run #0: crashed: INFO: task hung in grab_super 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 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 run #10: crashed: INFO: task hung in grab_super run #11: crashed: INFO: task hung in grab_super run #12: crashed: INFO: task hung in grab_super run #13: crashed: INFO: task hung in grab_super run #14: crashed: INFO: task hung in grab_super run #15: crashed: INFO: task hung in grab_super run #16: crashed: INFO: task hung in grab_super run #17: crashed: no output from test machine run #18: crashed: no output from test machine run #19: crashed: no output from test machine testing current HEAD b172b44fcb1771e083aad806fa96f3f60e2ddfac testing commit b172b44fcb1771e083aad806fa96f3f60e2ddfac compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 4bc1c6f29bd2ca717a4fa8619b5bef62967623e8a865975d09932f19d2e53a6e all runs: crashed: INFO: task hung in grab_super revisions tested: 2, total time: 31m42.503764622s (build: 16m58.491738255s, test: 14m9.425739633s) the crash still happens on HEAD commit msg: Linux 4.19.206 crash: INFO: task hung in grab_super Bluetooth: hci0: command 0x0406 tx timeout Bluetooth: hci3: command 0x0406 tx timeout Bluetooth: hci2: command 0x0406 tx timeout Bluetooth: hci5: command 0x0406 tx timeout Bluetooth: hci1: command 0x0406 tx timeout INFO: task syz-executor.0:10042 blocked for more than 140 seconds. Not tainted 4.19.206-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28744 10042 8461 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 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:589 [inline] rwsem_down_write_failed+0x3bb/0x780 kernel/locking/rwsem-xadd.c:618 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0x53/0x90 kernel/locking/rwsem.c:72 grab_super+0xaf/0x1f0 fs/super.c:383 sget_userns+0x6e6/0xb70 fs/super.c:511 sget+0xbe/0x100 fs/super.c:570 mount_bdev+0xc9/0x330 fs/super.c:1131 udf_mount+0x10/0x20 fs/udf/super.c:131 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: 0033:0x465b09 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f38c7297188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007ffdead94c9f R14: 00007f38c7297300 R15: 0000000000022000 INFO: task syz-executor.1:10051 blocked for more than 140 seconds. Not tainted 4.19.206-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D27496 10051 8470 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 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:589 [inline] rwsem_down_write_failed+0x3bb/0x780 kernel/locking/rwsem-xadd.c:618 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0x53/0x90 kernel/locking/rwsem.c:72 grab_super+0xaf/0x1f0 fs/super.c:383 sget_userns+0x6e6/0xb70 fs/super.c:511 sget+0xbe/0x100 fs/super.c:570 mount_bdev+0xc9/0x330 fs/super.c:1131 udf_mount+0x10/0x20 fs/udf/super.c:131 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: 0033:0x465b09 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f71985a8188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008 R13: 00007ffc3b63ac3f R14: 00007f71985a8300 R15: 0000000000022000 Showing all locks held in the system: 1 lock held by khungtaskd/1570: #0: 00000000aea9791a (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4443 1 lock held by in:imklog/7811: #0: 00000000014a0a03 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 1 lock held by syz-executor.0/10034: 2 locks held by syz-executor.0/10042: #0: 00000000b14e0604 (&bdev->bd_fsfreeze_mutex){+.+.}, at: mount_bdev+0x71/0x330 fs/super.c:1125 #1: 00000000fea36fb4 (&type->s_umount_key#49){+.+.}, at: grab_super+0xaf/0x1f0 fs/super.c:383 1 lock held by syz-executor.1/10040: 2 locks held by syz-executor.1/10051: #0: 0000000048f37c13 (&bdev->bd_fsfreeze_mutex){+.+.}, at: mount_bdev+0x71/0x330 fs/super.c:1125 #1: 0000000018a595d0 (&type->s_umount_key#49){+.+.}, at: grab_super+0xaf/0x1f0 fs/super.c:383 1 lock held by syz-executor.2/10114: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1570 Comm: khungtaskd Not tainted 4.19.206-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 CPU: 1 PID: 10034 Comm: syz-executor.0 Not tainted 4.19.206-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:lookup_bh_lru fs/buffer.c:1262 [inline] RIP: 0010:__find_get_block+0xb4/0xbb0 fs/buffer.c:1291 Code: 00 49 bc 00 00 00 00 00 fc ff df 45 31 ff e8 d3 c3 be ff eb 0e 41 83 c7 01 41 83 ff 10 0f 84 19 01 00 00 48 c7 c7 a0 00 14 88 77 e1 a5 01 44 89 fe 48 c7 c0 e0 87 02 00 65 48 8b 04 f0 48 85 RSP: 0018:ffff88808d617618 EFLAGS: 00000087 RAX: ffff8880ae1f6690 RBX: ffff8880ae1f6690 RCX: 0000000000000000 RDX: 1ffff11015c3ecd5 RSI: 0000000000000009 RDI: ffffffff881400a0 RBP: ffff88808d617668 R08: fffff9400040dc47 R09: fffff9400040dc46 R10: fffff9400040dc46 R11: ffffea000206e237 R12: dffffc0000000000 R13: 0000000000000001 R14: ffff8880b1b50080 R15: 000000000000000a FS: 00007f38c72b8700(0000) GS:ffff8880ba300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4c1e219600 CR3: 0000000099785000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __getblk_slow fs/buffer.c:1040 [inline] __getblk_gfp+0x140/0x7b0 fs/buffer.c:1321 __bread_gfp+0xa/0x190 fs/buffer.c:1366 sb_bread include/linux/buffer_head.h:309 [inline] udf_tread+0xdf/0x130 fs/udf/misc.c:44 udf_read_tagged+0x2b/0x470 fs/udf/misc.c:210 udf_check_anchor_block+0x197/0x640 fs/udf/super.c:1820 udf_scan_anchors+0x32d/0x550 fs/udf/super.c:1882 udf_find_anchor fs/udf/super.c:1917 [inline] udf_load_vrs+0x586/0xa20 fs/udf/super.c:1982 udf_fill_super+0x6d4/0x1410 fs/udf/super.c:2177 mount_bdev+0x26f/0x330 fs/super.c:1158 udf_mount+0x10/0x20 fs/udf/super.c:131 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: 0033:0x465b09 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f38c72b8188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09 RDX: 0000000020000040 RSI: 0000000020000280 RDI: 00000000200004c0 RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffdead94c9f R14: 00007f38c72b8300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12 7: fc ff df a: 45 31 ff xor %r15d,%r15d d: e8 d3 c3 be ff callq 0xffbec3e5 12: eb 0e jmp 0x22 14: 41 83 c7 01 add $0x1,%r15d 18: 41 83 ff 10 cmp $0x10,%r15d 1c: 0f 84 19 01 00 00 je 0x13b 22: 48 c7 c7 a0 00 14 88 mov $0xffffffff881400a0,%rdi * 29: e8 77 e1 a5 01 callq 0x1a5e1a5 <-- trapping instruction 2e: 44 89 fe mov %r15d,%esi 31: 48 c7 c0 e0 87 02 00 mov $0x287e0,%rax 38: 65 48 8b 04 f0 mov %gs:(%rax,%rsi,8),%rax 3d: 48 rex.W 3e: 85 .byte 0x85