[v6.1] INFO: rcu detected stall in generic_file_read_iter

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2fda4b3f577 Linux 6.1.156
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1605cb04580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=4d0902280155277d3208
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/10e802f3fcb6/disk-c2fda4b3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/66b88bca821f/vmlinux-c2fda4b3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5f220b7a420e/bzImage-c2fda4b3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d0902...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P18782/1:b..l
(detected by 1, t=10506 jiffies, g=67269, q=274 ncpus=2)
task:modprobe state:R running task stack:24352 pid:18782 ppid:4363 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:lock_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5710
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc9000db276c0 EFLAGS: 00000206
RAX: 07620cfe98856200 RBX: ffff88807d04bb80 RCX: 07620cfe98856200
RDX: ffff88807d04bb80 RSI: ffffffff8a8c1680 RDI: ffffffff8adef020
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffff9400007bf61
R10: fffff9400007bf61 R11: 1ffffd400007bf60 R12: 0000000000000000
R13: 0000000000000246 R14: ffffffff8cb2abe0 R15: ffff88807d04c660
xa_entry include/linux/xarray.h:1198 [inline]
xas_next+0x195/0x2a0 include/linux/xarray.h:1870
filemap_get_read_batch+0x590/0xa60 mm/filemap.c:2444
filemap_get_pages mm/filemap.c:2661 [inline]
filemap_read+0x556/0x2f80 mm/filemap.c:2759
generic_file_read_iter+0x115/0x670 mm/filemap.c:2914
call_read_iter include/linux/fs.h:2259 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x434/0x920 fs/read_write.c:470
ksys_read+0x143/0x240 fs/read_write.c:613
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: 0033:0x7f3c68abd134
RSP: 002b:00007ffc9661d608 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ffc9661d680 RCX: 00007f3c68abd134
RDX: 0000000000000340 RSI: 00007ffc9661d898 RDI: 0000000000000000
RBP: 00007ffc9661d670 R08: 00007ffc9661d877 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000340 R14: 00007ffc9661d890 R15: 00007ffc9661d898
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g67269 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=0 timer-softirq=91872
rcu: rcu_preempt kthread starved for 10502 jiffies! g67269 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26912 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
schedule+0xb9/0x180 kernel/sched/core.c:6637
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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:228 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:240 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:444 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1030 [inline]
RIP: 0010:trace_hrtimer_expire_entry include/trace/events/timer.h:239 [inline]
RIP: 0010:__run_hrtimer kernel/time/hrtimer.c:1744 [inline]
RIP: 0010:__hrtimer_run_queues+0x4ad/0xd60 kernel/time/hrtimer.c:1811
Code: 00 00 e8 e6 d8 0f 00 45 89 f7 41 c1 ee 06 4a 8d 3c f5 e8 67 1f 8e be 08 00 00 00 e8 4d 08 60 00 31 f6 4c 0f a3 3d cb 71 ae 0c <41> 0f 92 c6 40 0f 92 c6 bf 02 00 00 00 e8 11 db 0f 00 45 84 f6 74
RSP: 0018:ffffc90000007d20 EFLAGS: 00000047
RAX: ffffffff8170f501 RBX: ffff8880b8e2a6c8 RCX: ffffffff8170f613
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e1f67e8
RBP: ffffc90000007e88 R08: dffffc0000000000 R09: fffffbfff1c3ecfe
R10: fffffbfff1c3ecfe R11: 1ffffffff1c3ecfd R12: ffff888053f2d340
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000140 CR3: 00000000332e5000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
__sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 f7 62 af f7 e9 4c ff ff ff e8 ad 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d e7 03 65 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c807d88 EFLAGS: 000002c6
RAX: d38b0e357daf4f00 RBX: ffffffff8a219ec7 RCX: d38b0e357daf4f00
RDX: 0000000000000001 RSI: ffffffff8a8c0500 RDI: ffffffff8adef020
RBP: ffffffff8c807ec0 R08: dffffc0000000000 R09: ffffed10171c6afa
R10: ffffed10171c6afa R11: 1ffff110171c6af9 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8c8bc680 R15: 1ffffffff1c3ed3e
default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
cpuidle_idle_call kernel/sched/idle.c:191 [inline]
do_idle+0x1fc/0x570 kernel/sched/idle.c:303
cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
rest_init+0x2dc/0x300 init/main.c:733
arch_call_rest_init+0xa/0xa init/main.c:893
start_kernel+0x490/0x539 init/main.c:1140
secondary_startup_64_no_verify+0xcf/0xdb
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup