[v6.6] INFO: rcu detected stall in sys_getpid

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 355bd0b51d2f Linux 6.6.104
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11586962580000
kernel config: https://syzkaller.appspot.com/x/.config?x=dac93b93d3de2741
dashboard link: https://syzkaller.appspot.com/bug?extid=35993bdd136c7a8427a4
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1348d962580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a48962580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ef00d28b2c5b/disk-355bd0b5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7627cd51eb0a/vmlinux-355bd0b5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3fdd0a51dd65/bzImage-355bd0b5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+35993b...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5819/3:b..l
rcu: (detected by 1, t=10503 jiffies, g=9437, q=115 ncpus=2)
task:syz-executor164 state:R running task stack:28904 pid:5819 ppid:5812 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
filemap_map_pages+0x1069/0x1630 mm/filemap.c:3655
do_fault_around mm/memory.c:4573 [inline]
do_read_fault mm/memory.c:4606 [inline]
do_fault mm/memory.c:4753 [inline]
do_pte_missing mm/memory.c:3688 [inline]
handle_pte_fault mm/memory.c:5025 [inline]
__handle_mm_fault mm/memory.c:5166 [inline]
handle_mm_fault+0x379b/0x4920 mm/memory.c:5331
do_user_addr_fault+0xad0/0x12e0 arch/x86/mm/fault.c:1324
handle_page_fault arch/x86/mm/fault.c:1465 [inline]
exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7fcc3c439e73
RSP: 002b:00007ffcf3a2f5a8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fcc3c439e73
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 00005555576fc750 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcf3a2f9a8 R14: 0000000000000001 R15: 0000000000000001
</TASK>
rcu: rcu_preempt kthread starved for 10522 jiffies! g9437 f0x0 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:27560 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</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: 5821 Comm: syz-executor164 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__hrtimer_run_queues+0x97/0xc40 kernel/time/hrtimer.c:1791
Code: 81 48 8d 8c 24 c0 00 00 00 48 c1 e9 03 48 b8 f1 f1 f1 f1 00 f3 f3 f3 48 89 4c 24 68 4a 89 04 29 e8 1e dd 0f 00 48 89 5c 24 30 <48> 83 c3 44 48 89 d8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 63 0b
RSP: 0018:ffffc90000007d40 EFLAGS: 00000006
RAX: ffffffff8175b282 RBX: ffff8880b8e2b940 RCX: ffff88802f721e00
RDX: 0000000000010000 RSI: 0000004dc1de77f6 RDI: ffff8880b8e2b940
RBP: ffffc90000007e90 R08: ffffffff8e4a912f R09: 1ffffffff1c95225
R10: dffffc0000000000 R11: fffffbfff1c95226 R12: ffff8880b8e2b98c
R13: dffffc0000000000 R14: 000000000000000f R15: 0000000000000011
FS: 00007fcc3c3f96c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 0000000075fa9000 CR4: 00000000003506f0
Call Trace:
<IRQ>
hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
__sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_is_held_type+0x56/0x190 kernel/locking/lockdep.c:-1
Code: 0f 84 03 01 00 00 65 8b 05 1f 7e 94 75 85 c0 0f 85 f4 00 00 00 65 48 8b 1d 27 ae 95 75 83 bb dc 0a 00 00 00 0f 85 df 00 00 00 <41> 89 f7 49 89 fe 48 c7 04 24 00 00 00 00 9c 8f 04 24 4c 8b 2c 24
RSP: 0018:ffffc900045afe90 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88802f721e00 RCX: 1a1971df0e88af00
RDX: ffff88802f721e00 RSI: 00000000ffffffff RDI: ffffffff8cd2fc20
RBP: 00000000ffffffff R08: dffffc0000000000 R09: 1ffffffff21b4aa0
R10: dffffc0000000000 R11: fffffbfff21b4aa1 R12: 0000000000000001
R13: dffffc0000000000 R14: ffffffff8cbdf2c0 R15: ffff8880276e5968
__task_pid_nr_ns+0x1ef/0x460 kernel/pid.c:503
task_tgid_vnr include/linux/sched.h:1642 [inline]
__ia32_sys_getpid+0x1d/0x20 kernel/sys.c:960
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcc3c43a5c7
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d 32 de 08 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d3 aa fd ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 31 f6 31 ff e9 87 df 02 00 0f 1f 80 00
RSP: 002b:00007fcc3c3f8b88 EFLAGS: 00000206 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007fcc3c3f8cf0 RCX: 00007fcc3c43a5c7
RDX: 00007fcc3c3f8bc0 RSI: 00007fcc3c3f8cf0 RDI: 0000000000000021
RBP: 0000000000000000 R08: 00007fcc3c3f96c0 R09: 00007fcc3c3f96c0
R10: 0000000000000000 R11: 0000000000000206 R12: 00007fcc3c4c330c
R13: 0000000000000000 R14: 00007ffcf3a2f4e0 R15: 00007ffcf3a2f5c8
</TASK>


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