[syzbot] [block?] INFO: rcu detected stall in blkdev_common_ioctl (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 24ef02f934ee net: page_pool: fix UAF in __page_pool_releas..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=108b3a79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2ca5f2f2c4197664
dashboard link: https://syzkaller.appspot.com/bug?extid=9d041b75d7063b71360d
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=149dd69e580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17063949580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7a991674b71f/disk-24ef02f9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/67041713f1b8/vmlinux-24ef02f9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/670139f0d1da/bzImage-24ef02f9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d041b...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=1e8c/1/0x4000000000000000 softirq=16934/16934 fqs=1
rcu: (detected by 0, t=10505 jiffies, g=16269, q=1004 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 4979 Comm: udevd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_region_inline mm/kasan/generic.c:185 [inline]
RIP: 0010:kasan_check_range+0x20/0x2c0 mm/kasan/generic.c:200
Code: 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 55 41 57 41 56 41 55 41 54 53 b0 01 48 85 f6 0f 84 ae 01 00 00 4c 8d 04 37 49 39 f8 <0f> 82 36 02 00 00 49 b9 00 00 00 00 00 80 ff ff eb 0d cc cc cc 49
RSP: 0018:ffffc90000a08d00 EFLAGS: 00000002
RAX: 1ffff1100ef95601 RBX: 0000000000000010 RCX: ffffffff8bce3acf
RDX: 0000000000000001 RSI: 0000000000000010 RDI: ffff888077cab308
RBP: 0000000000000000 R08: ffff888077cab318 R09: 1ffffffff20af1e6
R10: dffffc0000000000 R11: fffffbfff20af1e7 R12: 1ffff110170e5060
R13: ffff888077cab300 R14: ffff888077cab308 R15: ffff8880b8728358
FS: 00007feea5050880(0000) GS:ffff888125049000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558c1f44e8 CR3: 000000007e048000 CR4: 00000000003526f0
Call Trace:
<IRQ>
__asan_memset+0x22/0x50 mm/kasan/shadow.c:84
rb_link_node include/linux/rbtree.h:96 [inline]
__rb_add include/linux/rbtree.h:238 [inline]
rb_add_linked include/linux/rbtree.h:281 [inline]
timerqueue_linked_add+0x23f/0x2e0 lib/timerqueue.c:96
enqueue_hrtimer+0x18e/0x2c0 kernel/time/hrtimer.c:1117
__run_hrtimer kernel/time/hrtimer.c:2048 [inline]
__hrtimer_run_queues+0x4ce/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:blkdev_common_ioctl+0x1cb1/0x3250 block/ioctl.c:712
Code: 8b 7c 24 10 66 c7 47 0c f8 f8 e9 0e f8 ff ff e8 15 c3 10 fd 41 bc ff ff ff ff 48 8b 7c 24 10 66 c7 47 10 f8 f8 e9 f3 f7 ff ff <e8> fa c2 10 fd 48 8b 5c 24 18 48 83 c3 10 48 89 d8 48 c1 e8 03 42
RSP: 0018:ffffc9000202fac0 EFLAGS: 00000246
RAX: ffffffff84b62dc6 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88807f680000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000202fdf0 R08: ffff8880238950b3 R09: 1ffff11004712a16
R10: dffffc0000000000 R11: ffffed1004712a17 R12: 0000000000000009
R13: dffffc0000000000 R14: ffff8880238950b0 R15: fffff52000405f60
blkdev_ioctl+0x528/0x740 block/ioctl.c:791
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
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: 0033:0x7feea491d378
Code: 00 00 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 07 89 d0 c3 0f 1f 40 00 48 8b 15 49 3a 0d
RSP: 002b:00007ffcb96a5f68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000055a9cc3c2180 RCX: 00007feea491d378
RDX: 0000000000000000 RSI: 000000000000125f RDI: 000000000000000c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000c
R13: 000055a9ade72100 R14: 0000000000000000 R15: 00007ffcb96a6160
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies! g16269 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=3345
rcu: rcu_preempt kthread starved for 10500 jiffies! g16269 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:27496 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>


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