[syzbot] [mm?] INFO: rcu detected stall in unmap_region

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 32f1c2bbb26a net: airoha: dma map xmit frags with skb_frag..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=116c2c0a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=86ba763b42fa66a
dashboard link: https://syzkaller.appspot.com/bug?extid=2ad5ec205a38c46522b3
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=132f5861580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7b7c3a22a8ed/disk-32f1c2bb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/168b43c87305/vmlinux-32f1c2bb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/70704720d284/bzImage-32f1c2bb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ad5ec...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=6664/1/0x4000000000000000 softirq=17730/17732 fqs=2
rcu: (detected by 1, t=10502 jiffies, g=17101, q=1895 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6010 Comm: modprobe Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:lock_release+0x5/0x3c0 kernel/locking/lockdep.c:5876
Code: e9 4f fe ff ff 41 bf 2f 00 00 00 e9 06 ff ff ff 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 30 49 89 f5 49 89 fe 65 48 8b
RSP: 0018:ffffc90000007db0 EFLAGS: 00000082
RAX: 932ea09fa7cced00 RBX: 0000000000000092 RCX: 0000000000000002
RDX: 0000000000000001 RSI: ffffffff81b30e19 RDI: ffffffff9a73d4c8
RBP: ffff88807e29b300 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f98 R12: ffff8880b86281c0
R13: dffffc0000000000 R14: ffffffff9a73d4b0 R15: ffff8880b8628350
FS: 0000000000000000(0000) GS:ffff888125226000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffae81e84e8 CR3: 000000007ee52000 CR4: 00000000003526f0
Call Trace:
<IRQ>
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:176 [inline]
_raw_spin_unlock_irqrestore+0x1b/0x80 kernel/locking/spinlock.c:198
debug_hrtimer_deactivate kernel/time/hrtimer.c:490 [inline]
__run_hrtimer kernel/time/hrtimer.c:2000 [inline]
__hrtimer_run_queues+0x239/0xa10 kernel/time/hrtimer.c:2096
hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:do_zap_pte_range mm/memory.c:1819 [inline]
RIP: 0010:zap_pte_range mm/memory.c:1934 [inline]
RIP: 0010:zap_pmd_range mm/memory.c:2020 [inline]
RIP: 0010:zap_pud_range mm/memory.c:2048 [inline]
RIP: 0010:zap_p4d_range mm/memory.c:2069 [inline]
RIP: 0010:__zap_vma_range+0xfbd/0x4f10 mm/memory.c:2109
Code: 4c 89 64 24 30 4c 89 e6 48 83 e6 9f 31 ff e8 3a 4a ad ff 4d 89 e7 49 83 e4 9f 75 2f 48 8b 44 24 10 4c 01 e8 48 83 f8 01 74 28 <e8> 3e 45 ad ff 48 83 c3 08 49 ff c5 4d 89 f4 eb a3 4d 89 ef e8 2a
RSP: 0018:ffffc90003287000 EFLAGS: 00000286
RAX: ffffffffffffff73 RBX: ffff888034e9d190 RCX: ffff88802dcf1f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900032872f0 R08: ffff888078979803 R09: 1ffff1100f12f300
R10: dffffc0000000000 R11: ffffed100f12f301 R12: 0000000000000000
R13: 0000000000000032 R14: dffffc0000000000 R15: 0000000000000000
unmap_vmas+0x390/0x550 mm/memory.c:2178
unmap_region+0x208/0x330 mm/vma.c:488
vms_clear_ptes mm/vma.c:1303 [inline]
vms_clean_up_area mm/vma.c:1315 [inline]
__mmap_setup mm/vma.c:2476 [inline]
__mmap_region mm/vma.c:2756 [inline]
mmap_region+0xc62/0x2310 mm/vma.c:2860
do_mmap+0xc3b/0x10c0 mm/mmap.c:560
vm_mmap_pgoff+0x272/0x4e0 mm/util.c:581
ksys_mmap_pgoff+0x4dc/0x760 mm/mmap.c:606
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffae8219242
Code: 08 00 04 00 00 eb e2 90 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 33 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 5e 5b 5d c3 0f 1f 00 c7 05 46 40 01 00 16 00
RSP: 002b:00007ffec64cd428 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007ffae7f73000 RCX: 00007ffae8219242
RDX: 0000000000000005 RSI: 000000000014e000 RDI: 00007ffae7f73000
RBP: 0000000000000812 R08: 0000000000000000 R09: 0000000000028000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffec64cd478
R13: 00007ffae81ed5f0 R14: 00007ffec64cdc60 R15: 00000fffd8c99a88
</TASK>
rcu: rcu_preempt kthread starved for 10477 jiffies! g17101 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28192 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 4992 Comm: udevd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x10b0/0x14b0 kernel/smp.c:892
Code: c0 75 73 41 8b 1e 89 de 83 e6 01 31 ff e8 d8 1e 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 84 1a 0c 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 69 1a 0c
RSP: 0018:ffffc90003837580 EFLAGS: 00000293
RAX: ffffffff81ba5717 RBX: dffffc0000000000 RCX: ffff88807e5a0000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900038376a8 R08: ffffffff9032d2f7 R09: 1ffffffff2065a5e
R10: dffffc0000000000 R11: fffffbfff2065a5f R12: 1ffff110170c85fd
R13: ffff8880b873c448 R14: ffff8880b8642fe8 R15: 0000000000000000
FS: 00007fdd3255d880(0000) GS:ffff888125326000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002c919703e000 CR3: 000000007e7f2000 CR4: 00000000003526f0
Call Trace:
<TASK>
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
__flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x5c4/0x1090 arch/x86/mm/tlb.c:1451
dup_mmap+0x1786/0x1d90 mm/mmap.c:1905
dup_mm kernel/fork.c:1538 [inline]
copy_mm+0x11a/0x480 kernel/fork.c:1590
copy_process+0x1e99/0x43f0 kernel/fork.c:2288
kernel_clone+0x2d7/0x940 kernel/fork.c:2747
__do_sys_clone kernel/fork.c:2888 [inline]
__se_sys_clone kernel/fork.c:2872 [inline]
__x64_sys_clone+0x1b6/0x230 kernel/fork.c:2872
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdd31ef1636
Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffcd95f6670 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffcd95f6678 RCX: 00007fdd31ef1636
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000564712dd5910 R08: 0000000000000000 R09: 0000564712ddd8e0
R10: 00007fdd3255db50 R11: 0000000000000246 R12: 00007ffcd95f6a30
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>


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