[v6.1] INFO: rcu detected stall in sys_exit_group (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 024f76bca9d0 Linux 6.1.49
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=136267b7a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a51973e83fb3785
dashboard link: https://syzkaller.appspot.com/bug?extid=d379c331ad4ccc35fac3
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c92f407988df/disk-024f76bc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dc4628bc4f9e/vmlinux-024f76bc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f5237e661249/bzImage-024f76bc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d379c3...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2967/1:b..l
(detected by 1, t=10502 jiffies, g=39657, q=125 ncpus=2)
task:udevd state:R running task stack:22120 pid:2967 ppid:1 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x132c/0x4330 kernel/sched/core.c:6554
preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6723
preempt_schedule+0xd9/0xe0 kernel/sched/core.c:6747
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0x128/0x130 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:405 [inline]
__wake_up_common_lock kernel/sched/wait.c:140 [inline]
__wake_up_sync_key+0x121/0x1c0 kernel/sched/wait.c:208
sock_def_readable+0x135/0x240 net/core/sock.c:3290
__netlink_sendskb net/netlink/af_netlink.c:1275 [inline]
netlink_sendskb+0x8e/0x120 net/netlink/af_netlink.c:1281
netlink_unicast+0x3a1/0x990 net/netlink/af_netlink.c:1369
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1903
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x59e/0x8f0 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x2a9/0x390 net/socket.c:2565
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f8302d86a4b
RSP: 002b:00007ffcf5d52298 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00005611aeee2df0 RCX: 00007f8302d86a4b
RDX: 0000000000000000 RSI: 00007ffcf5d522a8 RDI: 0000000000000004
RBP: 00005611aef01940 R08: 0000000000000001 R09: 0000000000000000
R10: 000000000000010f R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000000a7 R14: 0000000000000000 R15: 0000000000000000
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g39657 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=0 timer-softirq=32524
rcu: rcu_preempt kthread starved for 10502 jiffies! g39657 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack:26656 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x132c/0x4330 kernel/sched/core.c:6554
schedule+0xbf/0x180 kernel/sched/core.c:6630
schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1935
rcu_gp_fqs_loop+0x2c2/0x1010 kernel/rcu/tree.c:1661
rcu_gp_kthread+0xa3/0x3a0 kernel/rcu/tree.c:1860
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9547 Comm: syz-executor.3 Not tainted 6.1.49-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
RIP: 0010:rcu_is_watching+0x22/0xb0 kernel/rcu/tree.c:720
Code: ff ff ff e8 80 18 12 09 41 57 41 56 53 65 ff 05 5c 82 8f 7e e8 bf 30 12 09 89 c3 83 f8 08 73 76 49 bf 00 00 00 00 00 fc ff df <4c> 8d 34 dd 50 08 b9 8c 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08
RSP: 0018:ffffc900000079e0 EFLAGS: 00000093
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8169ed5b
RDX: 0000000000000000 RSI: ffffffff8b3cea80 RDI: ffffffff8b3cea40
RBP: ffffc90000007b48 R08: dffffc0000000000 R09: fffffbfff1ce7066
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000000f48
R13: dffffc0000000000 R14: 0000000000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000ce8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<IRQ>
trace_lock_acquire include/trace/events/lock.h:24 [inline]
lock_acquire+0xfa/0x5a0 kernel/locking/lockdep.c:5640
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
debug_object_activate+0x16a/0x890 lib/debugobjects.c:706
debug_hrtimer_activate kernel/time/hrtimer.c:420 [inline]
debug_activate kernel/time/hrtimer.c:475 [inline]
enqueue_hrtimer+0x30/0x390 kernel/time/hrtimer.c:1084
__run_hrtimer kernel/time/hrtimer.c:1702 [inline]
__hrtimer_run_queues+0x728/0xe50 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline]
__sysvec_apic_timer_interrupt+0x156/0x580 arch/x86/kernel/apic/apic.c:1112
sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1106
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:lock_acquire+0x26f/0x5a0 kernel/locking/lockdep.c:5673
Code: 2b 00 74 08 4c 89 f7 e8 6f a5 76 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc900166ff460 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92002cdfe98 RCX: 1ffff92002cdfe38
RDX: dffffc0000000000 RSI: ffffffff8aebf420 RDI: ffffffff8b3ceaa0
RBP: ffffc900166ff5c0 R08: dffffc0000000000 R09: fffffbfff2093445
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92002cdfe94
R13: dffffc0000000000 R14: ffffc900166ff4c0 R15: 0000000000000246
rcu_lock_acquire+0x20/0x30 include/linux/rcupdate.h:306
rcu_read_lock include/linux/rcupdate.h:747 [inline]
folio_memcg_lock+0x83/0x360 mm/memcontrol.c:2098
page_remove_rmap+0x2e/0xed0 mm/rmap.c:1426
zap_pte_range mm/memory.c:1443 [inline]
zap_pmd_range mm/memory.c:1564 [inline]
zap_pud_range mm/memory.c:1593 [inline]
zap_p4d_range mm/memory.c:1614 [inline]
unmap_page_range+0x1217/0x2740 mm/memory.c:1635
unmap_vmas+0x3c4/0x560 mm/memory.c:1720
exit_mmap+0x252/0x9f0 mm/mmap.c:3214
__mmput+0x115/0x3c0 kernel/fork.c:1191
exit_mm+0x226/0x300 kernel/exit.c:563
do_exit+0x67e/0x2300 kernel/exit.c:856
do_group_exit+0x202/0x2b0 kernel/exit.c:1019
__do_sys_exit_group kernel/exit.c:1030 [inline]
__se_sys_exit_group kernel/exit.c:1028 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1028
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f934547cae9
Code: Unable to access opcode bytes at 0x7f934547cabf.
RSP: 002b:00007ffe634dd388 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001e RCX: 00007f934547cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000504 R09: 0000000000000000
R10: 0000001b31620000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.