syzbot


INFO: task hung in ext4_put_super

Status: upstream: reported C repro on 2022/06/19 21:08
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+b72286444ed8911555bf@syzkaller.appspotmail.com
First crash: 733d, last: 482d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in ext4_put_super ext4 C inconclusive done 1 1102d 1131d 20/27 fixed on 2021/11/10 00:50
linux-4.19 INFO: task hung in ext4_put_super ext4 C error 5 510d 1124d 0/1 upstream: reported C repro on 2021/05/25 03:18
Fix bisection attempts (5)
Created Duration User Patch Repo Result
2023/02/25 21:56 22m bisect fix linux-4.14.y job log (0) log
2022/10/28 18:28 28m bisect fix linux-4.14.y job log (0) log
2022/09/17 23:00 23m bisect fix linux-4.14.y job log (0) log
2022/08/18 22:33 27m bisect fix linux-4.14.y job log (0) log
2022/07/19 22:04 28m bisect fix linux-4.14.y job log (0) log

Sample crash report:
EXT4-fs (loop0): re-mounted. Opts: (null)
EXT4-fs (loop0): re-mounted. Opts: (null)
EXT4-fs (loop0): re-mounted. Opts: (null)
EXT4-fs (loop0): re-mounted. Opts: (null)
INFO: task syz-executor398:8002 blocked for more than 140 seconds.
      Not tainted 4.14.304-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor398 D27952  8002   8000 0x00000000
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431
 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724
 do_wait_for_common kernel/sched/completion.c:91 [inline]
 __wait_for_common kernel/sched/completion.c:112 [inline]
 wait_for_common+0x272/0x430 kernel/sched/completion.c:123
 kthread_stop+0xce/0x640 kernel/kthread.c:555
 ext4_put_super+0x865/0xf00 fs/ext4/super.c:988
 generic_shutdown_super+0x144/0x370 fs/super.c:446
 kill_block_super+0x95/0xe0 fs/super.c:1161
 deactivate_locked_super+0x6c/0xd0 fs/super.c:319
 deactivate_super+0x7f/0xa0 fs/super.c:350
 cleanup_mnt+0x186/0x2c0 fs/namespace.c:1183
 task_work_run+0x11f/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+0x5e/0xd3
RIP: 0033:0x7fb82c678ce7
RSP: 002b:00007fff0778d8c8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fb82c678ce7
RDX: 00007fff0778d98c RSI: 000000000000000a RDI: 00007fff0778d980
RBP: 00007fff0778d980 R08: 00000000ffffffff R09: 00007fff0778d760
R10: 0000555556580683 R11: 0000000000000202 R12: 00007fff0778e9f0
R13: 00005555565805f0 R14: 00007fff0778d8f0 R15: 0000000000000a97

Showing all locks held in the system:
1 lock held by khungtaskd/1534:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8702d8de>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by syz-executor398/8002:
 #0:  (&type->s_umount_key#35){++++}, at: [<ffffffff81878287>] deactivate_super+0x77/0xa0 fs/super.c:349

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

NMI backtrace for cpu 1
CPU: 1 PID: 1534 Comm: khungtaskd Not tainted 4.14.304-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x180 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+0x5b9/0xb40 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:406
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4624 Comm: systemd-journal Not tainted 4.14.304-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
task: ffff8880a17d0140 task.stack: ffff8880a17d8000
RIP: 0010:___bpf_prog_run+0x86/0x5630 kernel/bpf/core.c:1006
RSP: 0018:ffff8880a17dfa48 EFLAGS: 00000a06
RAX: 1ffff9200035042e RBX: dffffc0000000000 RCX: ffff8880a17dfe68
RDX: ffffc90001a82170 RSI: ffffc90001a82030 RDI: ffffc90001a8216c
RBP: ffff8880a17dfb58 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff878f1680
R13: 1ffff110142fbf50 R14: ffffc90001a82170 R15: 0000000000000002
FS:  00007f905c25c8c0(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9059789000 CR3: 00000000a1042000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
Code: 48 8d 47 30 48 89 44 24 18 48 c1 e8 03 48 01 d8 c7 44 24 14 00 00 00 00 48 89 04 24 e8 34 ee f6 ff 4c 89 f0 4c 89 f2 48 c1 e8 03 <83> e2 07 0f b6 04 18 38 d0 7f 08 84 c0 0f 85 61 3e 00 00 45 0f 

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/01/25 12:53 linux-4.14.y 3949d1610004 9dfcf09c .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-4-14 INFO: task hung in ext4_put_super
2022/12/30 19:54 linux-4.14.y c4215ee4771b 44712fbc .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-4-14 INFO: task hung in ext4_put_super
2022/09/25 10:49 linux-4.14.y 4edbf74132a4 0042f2b4 .config console log report syz C [disk image] [vmlinux] ci2-linux-4-14 INFO: task hung in ext4_put_super
2022/06/19 21:07 linux-4.14.y 84bae26850e3 8f633d84 .config console log report syz C ci2-linux-4-14 INFO: task hung in ext4_put_super
* Struck through repros no longer work on HEAD.