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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 090666d3cc90 Linux 6.1.177
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11e742b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f5aae664b2df43c2
dashboard link: https://syzkaller.appspot.com/bug?extid=48762beee5a13074f99d
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0b218516a5e9/disk-090666d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3239ad568bdf/vmlinux-090666d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8b19cfbec3e/bzImage-090666d3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+48762b...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P8450/1:b..l
(detected by 1, t=10503 jiffies, g=51901, q=92 ncpus=2)
task:syz.1.1068 state:R running task stack:24304 pid:8450 ppid:4275 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6562
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
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:xas_descend+0xa/0x460 lib/xarray.c:202
Code: 44 89 f1 80 e1 07 38 c1 0f 8c 46 ff ff ff 4c 89 f7 89 f5 e8 58 5e b0 f7 89 ee e9 35 ff ff ff 90 55 41 57 41 56 41 55 41 54 53 <48> 83 ec 20 49 89 f5 48 89 fb 49 bf 00 00 00 00 00 fc ff df e8 1d
RSP: 0018:ffffc900059af228 EFLAGS: 00000293
RAX: ffffffff8a238018 RBX: dffffc0000000000 RCX: 0000000000000002
RDX: ffff8880733b9e00 RSI: ffff888067d70dc0 RDI: ffffc900059af268
RBP: 000000000000000c R08: dffffc0000000000 R09: 1ffffffff2162048
R10: dffffc0000000000 R11: fffffbfff2162049 R12: 1ffff1100cfae1b8
R13: 0000000000000000 R14: ffff888067d70dc2 R15: ffff888067d70dc0
xas_load lib/xarray.c:242 [inline]
xa_load+0x18a/0x2e0 lib/xarray.c:1463
__readahead_folio include/linux/pagemap.h:1289 [inline]
readahead_folio include/linux/pagemap.h:1322 [inline]
mpage_readahead+0x1f2/0x890 fs/mpage.c:357
read_pages+0x187/0x860 mm/readahead.c:161
page_cache_ra_unbounded+0x667/0x750 mm/readahead.c:270
filemap_readahead mm/filemap.c:2640 [inline]
filemap_get_pages mm/filemap.c:2681 [inline]
filemap_read+0x917/0x3150 mm/filemap.c:2759
blkdev_read_iter+0x42f/0x570 block/fops.c:668
call_read_iter include/linux/fs.h:2259 [inline]
aio_read+0x337/0x490 fs/aio.c:1575
__io_submit_one fs/aio.c:-1 [inline]
io_submit_one+0x6a3/0x1340 fs/aio.c:2034
__do_sys_io_submit fs/aio.c:2093 [inline]
__se_sys_io_submit+0x19d/0x310 fs/aio.c:2063
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ffb0679de99
RSP: 002b:00007ffb07725028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007ffb06a25fa0 RCX: 00007ffb0679de99
RDX: 00002000000000c0 RSI: 00000000000000ca RDI: 00007ffb076c2000
RBP: 00007ffb06833eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffb06a26038 R14: 00007ffb06a25fa0 R15: 00007fff187ec948
</TASK>
rcu: rcu_preempt kthread starved for 9661 jiffies! g51901 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:28112 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6562
schedule+0xb9/0x180 kernel/sched/core.c:6638
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
rcu_gp_kthread+0x99/0x3b0 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: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 67 01 99 f7 e9 44 ff ff ff e8 8d 03 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d f7 60 4c 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:ffffc90000177de8 EFLAGS: 000002c6
RAX: efe6d89056261700 RBX: ffffffff8a3a4b17 RCX: efe6d89056261700
RDX: 0000000000000001 RSI: ffffffff8a8c17a0 RDI: ffffffff8adf42e0
RBP: ffffc90000177f20 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888017701e00 R15: 1ffff9200002efc8
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c28bf86000 CR3: 000000002866e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
cpuidle_idle_call kernel/sched/idle.c:199 [inline]
do_idle+0x250/0x680 kernel/sched/idle.c:323
cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:422
start_secondary+0xe4/0xf0 arch/x86/kernel/smpboot.c:281
secondary_startup_64_no_verify+0xcf/0xdb
</TASK>


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