syzbot


INFO: task hung in sync_inodes_sb

Status: upstream: reported C repro on 2020/10/09 07:19
Reported-by: syzbot+ba079f8c3d13aff381ce@syzkaller.appspotmail.com
First crash: 676d, last: 253d

Fix bisection: failed (bisect log)
similar bugs (8):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in sync_inodes_sb (2) 4 1211d 1229d 0/23 auto-closed as invalid on 2019/10/19 16:22
upstream INFO: task hung in sync_inodes_sb (3) C done 6 955d 963d 16/23 fixed on 2020/02/14 01:19
upstream INFO: task hung in sync_inodes_sb 58 1309d 1547d 0/23 closed as dup on 2018/09/08 15:37
linux-4.14 INFO: task hung in sync_inodes_sb 1 924d 924d 0/1 auto-closed as invalid on 2020/06/02 17:26
android-49 INFO: task hung in sync_inodes_sb 11 1449d 1528d 0/3 auto-closed as invalid on 2019/02/24 06:19
android-49 INFO: task hung in sync_inodes_sb (2) 2 1038d 1200d 0/3 auto-closed as invalid on 2020/02/10 00:14
upstream INFO: task hung in sync_inodes_sb (4) C done inconclusive 6 125d 633d 0/23 upstream: reported C repro on 2020/11/21 04:55
linux-4.14 INFO: task hung in sync_inodes_sb (2) C 6 29d 585d 0/1 upstream: reported C repro on 2021/01/07 19:48

Sample crash report:
NILFS (loop0): broken superblock, retrying with spare superblock (blocksize = 2048)
NILFS (loop0): mounting unchecked fs
NILFS (loop0): recovery complete
NILFS (loop0): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds
INFO: task syz-executor026:6497 blocked for more than 140 seconds.
      Not tainted 4.19.150-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor026 D28240  6497   6491 0x00000000
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x8e5/0x22e0 kernel/sched/core.c:3517
 schedule+0x8d/0x1b0 kernel/sched/core.c:3561
 wb_wait_for_completion+0x175/0x1f0 fs/fs-writeback.c:222
 sync_inodes_sb+0x19d/0xa20 fs/fs-writeback.c:2483
 __sync_filesystem fs/sync.c:34 [inline]
 sync_filesystem+0x15c/0x250 fs/sync.c:67
 generic_shutdown_super+0x70/0x370 fs/super.c:442
 kill_block_super+0x97/0xf0 fs/super.c:1185
 deactivate_locked_super+0x8c/0x100 fs/super.c:329
 deactivate_super+0x174/0x1a0 fs/super.c:360
 cleanup_mnt+0x1da/0x300 fs/namespace.c:1098
 task_work_run+0x141/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x269/0x2c0 arch/x86/entry/common.c:167
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x57c/0x670 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44e0e7
Code: Bad RIP value.
RSP: 002b:00007ffebb447b88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00000000000ccd60 RCX: 000000000044e0e7
RDX: 0000000000400d27 RSI: 0000000000000002 RDI: 00007ffebb447c30
RBP: 0000000000001962 R08: 0000000000000000 R09: 0000000000000009
R10: 0000000000000005 R11: 0000000000000206 R12: 00007ffebb448ce0
R13: 0000000000b33880 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1089:
 #0: 00000000cfdb6ce9 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x291 kernel/locking/lockdep.c:4440
2 locks held by kworker/u4:4/2429:
 #0: 00000000d05bc792 ((wq_completion)"writeback"){+.+.}, at: process_one_work+0x692/0x14e0 kernel/workqueue.c:2126
 #1: 0000000050327741 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x6c8/0x14e0 kernel/workqueue.c:2130
1 lock held by in:imklog/6188:
 #0: 0000000011c897b5 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767
2 locks held by syz-executor026/6497:
 #0: 00000000eec867a1 (&type->s_umount_key#59){+.+.}, at: deactivate_super+0x16c/0x1a0 fs/super.c:359
 #1: 000000002119cf64 (&bdi->wb_switch_rwsem){+.+.}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:338 [inline]
 #1: 000000002119cf64 (&bdi->wb_switch_rwsem){+.+.}, at: sync_inodes_sb+0x180/0xa20 fs/fs-writeback.c:2481

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1089 Comm: khungtaskd Not tainted 4.19.150-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+0x22c/0x33e lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x18/0x3d lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
 watchdog+0xa62/0x1020 kernel/hung_task.c:287
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3708 Comm: systemd-journal Not tainted 4.19.150-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:lockdep_sys_exit+0x2e/0x50 kernel/locking/lockdep.c:4480
Code: 00 00 00 fc ff df 55 65 48 8b 2c 25 40 ee 01 00 48 8d bd 80 08 00 00 48 89 fa 48 c1 ea 03 0f b6 04 02 84 c0 74 04 3c 03 7e 1b <8b> 85 80 08 00 00 85 c0 75 02 5d c3 e8 61 60 46 02 85 c0 0f 85 84
RSP: 0018:ffff8880944aff18 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8880944a0680 RCX: ffffffff8100a851
RDX: 1ffff110128941e0 RSI: ffffffff8100a71f RDI: ffff8880944a0f00
RBP: ffff8880944a0680 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff896389f8 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f2ec9afc8c0(0000) GS:ffff8880ae200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2ec6ea5000 CR3: 0000000094861000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 prepare_exit_to_usermode arch/x86/entry/common.c:193 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x304/0x670 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f2ec8db8687
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:00007ffdfe530c38 EFLAGS: 00000293 ORIG_RAX: 0000000000000053
RAX: fffffffffffffffe RBX: 00007ffdfe533ca0 RCX: 00007f2ec8db8687
RDX: 0000000000000000 RSI: 00000000000001ed RDI: 00005633b2fae8c0
RBP: 00007ffdfe530c70 R08: 00005633b1ce13e5 R09: 0000000000000018
R10: 0000000000000069 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000001 R14: 00005633b2fae8c0 R15: 00007ffdfe5312b0

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-19 2020/10/14 16:02 linux-4.19.y a1b977b49b66 fc7735a2 .config log report syz C
ci2-linux-4-19 2020/10/09 07:18 linux-4.19.y a1b977b49b66 92390980 .config log report syz C
ci2-linux-4-19 2021/12/05 11:55 linux-4.19.y 3f8a27f9e27b a617004c .config log report info INFO: task hung in sync_inodes_sb
ci2-linux-4-19 2021/11/23 12:11 linux-4.19.y 3f8a27f9e27b 545ab074 .config log report info INFO: task hung in sync_inodes_sb