[v5.15] INFO: rcu detected stall in msr_read (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 93741761e5e3 Linux 5.15.207
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11b778ec580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=96a90360fd8f679b5b02
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7087b65c18a1/disk-93741761.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5892df79f094/vmlinux-93741761.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4602fe2cead2/bzImage-93741761.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+96a903...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4291/1:b..l
(detected by 0, t=10502 jiffies, g=65757, q=355)
task:kworker/u4:9 state:R running task stack:23312 pid: 4291 ppid: 2 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc900031efaa0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 77b9737b84051200
RDX: 0000000000000000 RSI: ffffffff8a2b43a0 RDI: ffffffff8a7a0700
RBP: ffffc900031efbc0 R08: dffffc0000000000 R09: 1ffffffff203ac18
R10: dffffc0000000000 R11: fffffbfff203ac19 R12: ffffffff8c31f320
R13: 1ffff9200063df60 R14: 0000000000000246 R15: dffffc0000000000
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
batadv_nc_worker+0xc9/0x5c0 net/batman-adv/network-coding.c:723
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10496 jiffies! g65757 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=26879
rcu: rcu_preempt kthread starved for 10497 jiffies! g65757 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:26960 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 11138 Comm: syz.2.1529 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:rb_erase_cached include/linux/rbtree.h:124 [inline]
RIP: 0010:timerqueue_del+0x9b/0x100 lib/timerqueue.c:57
Code: 07 e8 d9 17 72 fd eb 26 e8 d2 17 72 fd 4c 89 f7 e8 0a 71 ff ff 43 80 3c 2f 00 74 0e 4c 89 e7 49 89 c7 e8 08 37 b7 fd 4c 89 f8 <49> 89 04 24 4c 89 f7 48 89 de e8 76 5a ff ff 42 80 7c 2d 00 00 74
RSP: 0018:ffffc90000dd0d08 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8880b912a390 RCX: ffff888022e4bb80
RDX: 0000000000010000 RSI: ffff88802b591340 RDI: ffff88802b591340
RBP: 1ffff110056b2268 R08: ffff88802b591357 R09: ffff88802b591340
R10: dffffc0000000000 R11: ffffed10056b226b R12: ffff8880b912a398
R13: dffffc0000000000 R14: ffff88802b591340 R15: 1ffff11017225473
FS: 00007f1651a506c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000001a000 CR3: 00000000641f7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
__remove_hrtimer kernel/time/hrtimer.c:1102 [inline]
__run_hrtimer kernel/time/hrtimer.c:1665 [inline]
__hrtimer_run_queues+0x366/0xb70 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90003c37a60 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 91ae31a11e3c7d00
RDX: 0000000000000000 RSI: ffffffff8a2b43a0 RDI: ffffffff8a7a0700
RBP: ffffc90003c37b80 R08: dffffc0000000000 R09: 1ffffffff203ac1e
R10: dffffc0000000000 R11: fffffbfff203ac1f R12: ffff88807e5f6a28
R13: 1ffff92000786f58 R14: 0000000000000246 R15: dffffc0000000000
__might_fault+0xb3/0x110 mm/memory.c:5357
_copy_to_user+0x29/0x130 lib/usercopy.c:35
copy_to_user include/linux/uaccess.h:200 [inline]
msr_read+0x127/0x1b0 arch/x86/kernel/msr.c:70
vfs_read+0x301/0xd60 fs/read_write.c:483
ksys_read+0x152/0x260 fs/read_write.c:623
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1653817e59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1651a50028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f1653a91090 RCX: 00007f1653817e59
RDX: 0000000000018ff8 RSI: 0000200000019680 RDI: 0000000000000005
RBP: 00007f16538add6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1653a91128 R14: 00007f1653a91090 R15: 00007ffe6e2a3f78
</TASK>


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