syzbot


INFO: task hung in __writeback_inodes_sb_nr

Status: auto-closed as invalid on 2020/09/27 19:31
Reported-by: syzbot+3863c61f094e29e1edb2@syzkaller.appspotmail.com
First crash: 848d, last: 848d
similar bugs (7):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in __writeback_inodes_sb_nr 53 1350d 1613d 0/24 closed as dup on 2018/09/08 15:33
android-49 INFO: task hung in __writeback_inodes_sb_nr 26 1446d 1590d 0/3 auto-closed as invalid on 2019/04/08 13:33
android-414 INFO: task hung in __writeback_inodes_sb_nr 1 1384d 1261d 0/1 auto-closed as invalid on 2019/06/09 16:55
upstream INFO: task hung in __writeback_inodes_sb_nr (5) C done 5 88d 226d 23/24 internal: reported C repro on 2022/02/12 04:17
upstream INFO: task hung in __writeback_inodes_sb_nr (4) 4 233d 288d 0/24 closed as invalid on 2022/02/08 10:10
upstream INFO: task hung in __writeback_inodes_sb_nr (3) 2 500d 597d 0/24 auto-closed as invalid on 2021/08/11 17:49
upstream INFO: task hung in __writeback_inodes_sb_nr (2) 1 782d 782d 0/24 auto-closed as invalid on 2020/11/03 06:13

Sample crash report:
Out of memory: Kill process 21254 (syz-executor.5) score 1007 or sacrifice child
Killed process 21254 (syz-executor.5) total-vm:75368kB, anon-rss:16548kB, file-rss:34816kB, shmem-rss:0kB
oom_reaper: reaped process 21254 (syz-executor.5), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
INFO: task syz-executor.4:6351 blocked for more than 140 seconds.
      Not tainted 4.14.182-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D25104  6351      1 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x8a6/0x1d70 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 wb_wait_for_completion fs/fs-writeback.c:221 [inline]
 wb_wait_for_completion+0x118/0x170 fs/fs-writeback.c:217
 __writeback_inodes_sb_nr+0x168/0x1d0 fs/fs-writeback.c:2357
 __sync_filesystem fs/sync.c:36 [inline]
 sync_filesystem+0x8c/0x230 fs/sync.c:64
 ovl_sync_fs+0xa8/0xe0 fs/overlayfs/super.c:259
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem fs/sync.c:67 [inline]
 sync_filesystem+0x185/0x230 fs/sync.c:48
 generic_shutdown_super+0x70/0x370 fs/super.c:432
 kill_anon_super+0x38/0x50 fs/super.c:1006
 deactivate_locked_super+0x6c/0xd0 fs/super.c:319
 deactivate_super fs/super.c:350 [inline]
 deactivate_super+0x7f/0xa0 fs/super.c:346
 cleanup_mnt+0xad/0x140 fs/namespace.c:1183
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 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+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45f497
RSP: 002b:00007fff6e714a38 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000176571 RCX: 000000000045f497
RDX: 00000000004031d8 RSI: 0000000000000002 RDI: 00007fff6e714ae0
RBP: 0000000000001bc7 R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000005 R11: 0000000000000202 R12: 00007fff6e715b70
R13: 0000000002989940 R14: 0000000000000000 R15: 00007fff6e715b70

Showing all locks held in the system:
1 lock held by khungtaskd/1057:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8146c8d0>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
2 locks held by syz-executor.4/6351:
 #0:  (&type->s_umount_key#64){+.+.}, at: [<ffffffff818c3a37>] deactivate_super fs/super.c:349 [inline]
 #0:  (&type->s_umount_key#64){+.+.}, at: [<ffffffff818c3a37>] deactivate_super+0x77/0xa0 fs/super.c:346
 #1:  (&type->s_umount_key#47){++++}, at: [<ffffffff82212d20>] ovl_sync_fs+0xa0/0xe0 fs/overlayfs/super.c:258

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

NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.182-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+0x1b2/0x283 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e2/0xb80 kernel/hung_task.c:274
 kthread+0x30d/0x420 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: 6114 Comm: kworker/u4:3 Not tainted 4.14.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
task: ffff88809ea98000 task.stack: ffff88820e240000
RIP: 0010:__sanitizer_cov_trace_pc+0x23/0x50 kernel/kcov.c:68
RSP: 0018:ffff88820e247a18 EFLAGS: 00000246
RAX: ffff88809ea98000 RBX: ffff888215474440 RCX: 1ffff1100a5f0b2e
RDX: 0000000000000000 RSI: ffff88820e247aa8 RDI: ffff888067389218
RBP: dffffc0000000000 R08: 0000000000000d3e R09: ffffffff89e5b330
R10: ffff88809ea988d8 R11: ffff88809ea98000 R12: ffff8880a18f8b70
R13: ffff88820e247bc0 R14: ffff888215474440 R15: ffff88820e247aa8
FS:  0000000000000000(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f149b4ff4a0 CR3: 0000000007a6a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 move_expired_inodes+0x294/0x870 fs/fs-writeback.c:1172
 queue_io+0x18e/0x4b0 fs/fs-writeback.c:1213
 wb_writeback+0x7ed/0xba0 fs/fs-writeback.c:1805
 wb_do_writeback fs/fs-writeback.c:1939 [inline]
 wb_workfn+0x2a8/0xe70 fs/fs-writeback.c:1975
 process_one_work+0x7c0/0x14c0 kernel/workqueue.c:2116
 worker_thread+0x5d7/0x1080 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 00 00 e9 be ed ff ff 90 65 48 8b 04 25 40 ee 01 00 48 85 c0 74 1a 65 8b 15 4b 48 a7 7e 81 e2 00 01 1f 00 75 0b 8b 90 58 13 00 00 <83> fa 01 74 01 c3 48 8b 34 24 48 8b 88 60 13 00 00 8b 80 5c 13 

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/05/30 19:30 linux-4.14.y 4f68020fef1c 6f3e1c7c .config log report
* Struck through repros no longer work on HEAD.