linux-kernel - [BUG] INFO: rcu detected stall in sys_io

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Message-ID: <CAJNGr6u38oVsWeh57rmW15H80DpPrd0CH0uLH5kff1W0v6SHLw@mail.gmail.com>
Date: Mon, 19 May 2025 12:39:44 +0800
From: Guoyu Yin <y04609127@...il.com>
To: anna-maria@...utronix.de
Cc: frederic@...nel.org, tglx@...utronix.de, linux-kernel@...r.kernel.org, 
	akpm@...ux-foundation.org, linux-mm@...ck.org
Subject: [BUG] INFO: rcu detected stall in sys_io_submit

Hi,

I discovered a kernel crash using the Syzkaller framework, described
as "INFO: rcu detected stall in sys_io_submit". This issue occurs
during the execution of the sys_io_submit system call, where RCU
detects a stall on CPU 3.

>From the dmesg log, CPU 3 is stuck in the enqueue_hrtimer function
(kernel/time/hrtimer.c:1085) while handling an hrtimer interrupt.
Meanwhile, the task syz-executor.1 is stuck in memory management
functions (e.g., unmap_mapping_pages, mm/memory.c:3849) during
sys_io_submit execution. This likely causes the RCU stall.

I suspect this is due to delays in hrtimer processing or prolonged
blocking in memory management operations. I recommend reviewing the
enqueue_hrtimer implementation and the interaction between
sys_io_submit, AIO, and the EXT4 filesystem.

The full dmesg log is attached. Please feel free to contact me for
additional information or reproduction steps.

This can be reproduced on:

HEAD commit:

fac04efc5c793dccbd07e2d59af9f90b7fc0dca4

report: https://pastebin.com/raw/D6PmW878

console output : https://pastebin.com/raw/qeLqJsRF

kernel config: https://pastebin.com/raw/zrj9jd1V

C reproducer : https://pastebin.com/raw/EprKHENh

Best regards,

Guoyu