linux-kernel - Re: [syzbot] [kernel?] INFO: rcu detected stall in sys

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Message-ID: <67b69a13.050a0220.14d86d.0155.GAE@google.com>
Date: Wed, 19 Feb 2025 18:57:23 -0800
From: syzbot <syzbot+b66b5182718939fec09b@...kaller.appspotmail.com>
To: andrealmeid@...lia.com, dave@...olabs.net, dvhart@...radead.org, 
	linux-kernel@...r.kernel.org, mingo@...hat.com, peterz@...radead.org, 
	syzkaller-bugs@...glegroups.com, tglx@...utronix.de
Subject: Re: [syzbot] [kernel?] INFO: rcu detected stall in sys_futex (7)

syzbot has found a reproducer for the following issue on:

HEAD commit:    6537cfb395f3 Merge tag 'sound-6.14-rc4' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17365ae4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f4f6914bcba459be
dashboard link: https://syzkaller.appspot.com/bug?extid=b66b5182718939fec09b
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10b65ae4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/699131ad8762/disk-6537cfb3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/70eae7bb5752/vmlinux-6537cfb3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b2de8da174e5/bzImage-6537cfb3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b66b5182718939fec09b@...kaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=e2cc/1/0x4000000000000000 softirq=15501/15501 fqs=0
rcu: 	(detected by 0, t=10505 jiffies, g=7317, q=400 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6093 Comm: syz.2.21 Not tainted 6.14.0-rc3-syzkaller-00060-g6537cfb395f3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:__lock_acquire+0xaa7/0x3c40 kernel/locking/lockdep.c:5211
Code: 48 83 fb ff 0f 85 03 0a 00 00 c7 84 24 84 00 00 00 01 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 c8 28 00 00 48 8b 54 24 30 49 89 1f 48 b8 00 00 00 00 00 fc
RSP: 0018:ffffc90000a18af0 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: fb268dbe5ff7dd64 RCX: ffffffff81966d32
RDX: 1ffff1100619c163 RSI: 0000000000000008 RDI: ffffffff96ec2cc0
RBP: 0000000000000040 R08: 0000000000000000 R09: fffffbfff2dd8598
R10: ffffffff96ec2cc7 R11: 0000000000000001 R12: ffffed100619c15d
R13: ffff888030ce0000 R14: 0000000000000002 R15: ffff888030ce0b18
FS:  00007fe83a63f6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000400000000600 CR3: 0000000079236000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
 debug_object_deactivate+0x13b/0x370 lib/debugobjects.c:873
 debug_hrtimer_deactivate kernel/time/hrtimer.c:460 [inline]
 debug_deactivate kernel/time/hrtimer.c:502 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1769 [inline]
 __hrtimer_run_queues+0x47c/0xae0 kernel/time/hrtimer.c:1865
 hrtimer_interrupt+0x392/0x8e0 kernel/time/hrtimer.c:1927
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x10f/0x400 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 a6 f9 3c f6 48 89 df e8 fe 78 3d f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 85 4f 2e f6 65 8b 05 a6 33 aa 74 85 c0 74 16 5b
RSP: 0018:ffffc90003097b88 EFLAGS: 00000246
RAX: 0000000000000002 RBX: ffff88802d0fd290 RCX: 1ffffffff20c4171
RDX: 0000000000000000 RSI: ffffffff8b6ceca0 RDI: ffffffff8bd35480
RBP: 0000000000000283 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90624f17 R11: 0000000000000002 R12: ffff88802d0fc894
R13: ffff88802d0fd290 R14: ffff88802d0fc880 R15: ffffc90003097be8
 class_raw_spinlock_irqsave_destructor include/linux/spinlock.h:551 [inline]
 try_to_wake_up+0x949/0x1490 kernel/sched/core.c:4214
 wake_up_process kernel/sched/core.c:4463 [inline]
 wake_up_q+0x9c/0x160 kernel/sched/core.c:1075
 futex_wake+0x43e/0x4e0 kernel/futex/waitwake.c:199
 do_futex+0x1e5/0x350 kernel/futex/syscalls.c:107
 __do_sys_futex kernel/futex/syscalls.c:179 [inline]
 __se_sys_futex kernel/futex/syscalls.c:160 [inline]
 __x64_sys_futex+0x1e1/0x4c0 kernel/futex/syscalls.c:160
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe83978cde9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe83a63f0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007fe8399a5fa8 RCX: 00007fe83978cde9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007fe8399a5fac
RBP: 00007fe8399a5fa0 R08: 00007fe83a640000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe8399a5fac
R13: 0000000000000000 R14: 00007ffd885fcba0 R15: 00007ffd885fcc88
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10504 jiffies! g7317 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=3496
rcu: rcu_preempt kthread starved for 10505 jiffies! g7317 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
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:27456 pid:17    tgid:17    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0xf43/0x5890 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6857
 schedule_timeout+0x124/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2024
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2226
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


---
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#syz test: git://repo/address.git branch-or-commit-hash
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