syzbot


INFO: task hung in ppp_release (5)

Status: auto-obsoleted due to no activity on 2025/04/21 19:30
Subsystems: ppp
[Documentation on labels]
First crash: 112d, last: 112d
Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in ppp_release 1 343d 343d 0/3 auto-obsoleted due to no activity on 2024/09/12 19:28
upstream INFO: task hung in ppp_release (3) ppp 13 310d 366d 0/28 auto-obsoleted due to no activity on 2024/09/10 18:31
linux-6.1 INFO: task hung in ppp_release 1 337d 337d 0/3 auto-obsoleted due to no activity on 2024/09/18 07:06
upstream INFO: task hung in ppp_release ppp 1 1809d 1809d 0/28 auto-closed as invalid on 2020/08/28 19:07
upstream INFO: task hung in ppp_release (2) ppp 1 1337d 1337d 0/28 auto-closed as invalid on 2021/12/13 06:07
upstream INFO: task hung in ppp_release (4) ppp 22 198d 234d 0/28 auto-obsoleted due to no activity on 2024/12/16 17:48
android-49 INFO: task hung in ppp_release 1 2224d 2221d 0/3 auto-closed as invalid on 2019/10/08 10:46

Sample crash report:
INFO: task syz.3.203:6642 blocked for more than 145 seconds.
      Not tainted 6.13.0-syzkaller-00603-g3d3a9c8b89d4 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.203       state:D stack:25328 pid:6642  tgid:6642  ppid:5816   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0xe58/0x5ad0 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6848
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6905
 __mutex_lock_common kernel/locking/mutex.c:665 [inline]
 __mutex_lock+0x62b/0xa60 kernel/locking/mutex.c:735
 ppp_release+0x167/0x230 drivers/net/ppp/ppp_generic.c:408
 __fput+0x3f8/0xb60 fs/file_table.c:450
 task_work_run+0x14e/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbe13785d29
RSP: 002b:00007ffeb4a5ab58 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fbe13977ba0 RCX: 00007fbe13785d29
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fbe13977ba0 R08: 00000000000077ac R09: 00007ffeb4a5ae4f
R10: 00007fbe13977ac0 R11: 0000000000000246 R12: 00000000000219db
R13: 00007fbe13976240 R14: 0000000000000032 R15: ffffffffffffffff
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x7f/0x390 kernel/locking/lockdep.c:6744
3 locks held by kworker/1:1/47:
 #0: ffff88801b079948 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3211
 #1: ffffc90000b77d80 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3212
 #2: ffffffff8fef1648 (rtnl_mutex){+.+.}-{4:4}, at: reg_check_chans_work+0x84/0x1130 net/wireless/reg.c:2480
3 locks held by kworker/R-ipv6_/3163:
 #0: ffff88814d332948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3211
 #1: ffffc9000c6d7d18 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3212
 #2: ffffffff8fef1648 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4755
3 locks held by syslogd/5174:
 #0: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:606 [inline]
 #0: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:591
 #1: ffff8880b8728a88 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2c1/0x8e0 kernel/sched/psi.c:987
 #2: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #2: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: filemap_get_entry+0xd0/0x3c0 mm/filemap.c:1829
1 lock held by klogd/5181:
2 locks held by udevd/5192:
2 locks held by dhcpcd/5485:
2 locks held by getty/5579:
 #0: ffff888031f750a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211
1 lock held by dhcpcd/5629:
1 lock held by syz-executor/5804:
1 lock held by syz-executor/5814:
1 lock held by syz-executor/5817:
 #0: ffffffff8e1c75f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x282/0x3b0 kernel/rcu/tree_exp.h:297
2 locks held by syz-executor/5827:
3 locks held by syz.2.209/6661:
2 locks held by syz.3.203/6642:
 #0: ffffffff8fef1648 (rtnl_mutex){+.+.}-{4:4}, at: ppp_release+0x167/0x230 drivers/net/ppp/ppp_generic.c:408
 #1: ffffffff8e1c75f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a4/0x3b0 kernel/rcu/tree_exp.h:329
3 locks held by syz-executor/6671:
6 locks held by kworker/0:8/6675:
 #0: ffff8881416ff148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3211
 #1: ffffc90004f57d80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3212
 #2: ffff888145758190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1014 [inline]
 #2: ffff888145758190 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c1/0x4e10 drivers/usb/core/hub.c:5851
 #3: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:606 [inline]
 #3: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:591
 #4: ffff8880b8628a88 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2c1/0x8e0 kernel/sched/psi.c:987
 #5: ffff8880b8628a88 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_change+0x1a2/0x2d0 kernel/sched/psi.c:912
1 lock held by dhcpcd/6677:
 #0: ffff8880aa21e258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1623 [inline]
 #0: ffff8880aa21e258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf60 net/packet/af_packet.c:3253

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-syzkaller-00603-g3d3a9c8b89d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xf14/0x1240 kernel/hung_task.c:397
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/21 19:22 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in ppp_release
* Struck through repros no longer work on HEAD.