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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f89b6e15694c Linux 6.1.149
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14569662580000
kernel config: https://syzkaller.appspot.com/x/.config?x=115cdcc5760d448b
dashboard link: https://syzkaller.appspot.com/bug?extid=7dca4d8f5e1c02ee5ebf
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/394a7db0dd9e/disk-f89b6e15.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fbc1ab2ec301/vmlinux-f89b6e15.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6d7c129efafb/bzImage-f89b6e15.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7dca4d...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 0, t=10502 jiffies, g=18353, q=36 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294963862-4294953359), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10504 jiffies! g18353 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:27848 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
irqentry_exit+0x63/0x70 kernel/entry/common.c:439
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:check_region_inline mm/kasan/generic.c:169 [inline]
RIP: 0010:kasan_check_range+0x2/0x290 mm/kasan/generic.c:189
Code: c6 48 89 c7 e8 0f 0d 47 08 31 c0 c3 0f 0b b8 ea ff ff ff c3 0f 0b b8 ea ff ff ff c3 00 00 cc cc 00 00 cc cc 00 00 cc cc b0 01 <48> 85 f6 0f 84 a4 01 00 00 41 57 41 56 53 49 89 f8 49 01 f0 0f 82
RSP: 0018:ffffc90000157b98 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffff88813fed5940 RCX: ffffffff8a1fe020
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88813fed5940
RBP: ffffc90000157cb0 R08: dffffc0000000000 R09: ffffed10171c7551
R10: ffffed10171c7551 R11: 1ffff110171c7550 R12: 1ffff9200002af78
R13: 1ffffffff1901e40 R14: 1ffff11027fdab28 R15: dffffc0000000000
instrument_atomic_read include/linux/instrumented.h:72 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
test_ti_thread_flag include/linux/thread_info.h:118 [inline]
need_resched include/linux/sched.h:2230 [inline]
schedule+0xd0/0x180 kernel/sched/core.c:6639
schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 6045 Comm: syz.2.596 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:lock_release+0x593/0x910 kernel/locking/lockdep.c:5686
Code: 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 75 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 66 43 c7 44 2f 09 00 00 43 c6 44 2f 0b 00
RSP: 0018:ffffc9000dc67dc0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: c4089029a8d1f300
RDX: 0000000000000000 RSI: ffffffff8a8c1480 RDI: ffffffff8adefae0
RBP: ffffc9000dc67ec8 R08: dffffc0000000000 R09: fffffbfff1c3ee26
R10: fffffbfff1c3ee26 R11: 1ffffffff1c3ee25 R12: ffff88802f9d0ae0
R13: dffffc0000000000 R14: ffff88802f9d0ad0 R15: 1ffff92001b8cfc4
FS: 00007fa8e4dd46c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005c9df000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rcu_lock_release include/linux/rcupdate.h:355 [inline]
rcu_read_unlock include/linux/rcupdate.h:824 [inline]
__task_pid_nr_ns+0x387/0x460 kernel/pid.c:501
task_tgid_vnr include/linux/sched.h:1628 [inline]
__ia32_sys_getpid+0x19/0x20 kernel/sys.c:953
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa8e3f85ba7
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d f2 6c d7 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 f3 f7 fb ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007fa8e4dd3b08 EFLAGS: 00000202 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007fa8e4dd3c70 RCX: 00007fa8e3f85ba7
RDX: 00007fa8e4dd3b40 RSI: 00007fa8e4dd3c70 RDI: 0000000000000021
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fa8e41c6038 R14: 00007fff260cc8b0 R15: 00007fff260cc998
</TASK>


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