From: Christian Brauner <brauner@kernel.org>
To: 白烁冉 <baishuoran@hrbeu.edu.cn>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org, Kun Hu <huk23@m.fudan.edu.cn>,
Jiaji Qin <jjtan24@m.fudan.edu.cn>,
linux-kernel@vger.kernel.org, syzkaller@googlegroups.com
Subject: Re: INFO: task hung in chmod_common
Date: Thu, 3 Apr 2025 12:30:49 +0200 [thread overview]
Message-ID: <20250403-teppich-geist-a877dd4158f2@brauner> (raw)
In-Reply-To: <79192769.9da0.195faff9e75.Coremail.baishuoran@hrbeu.edu.cn>
On Thu, Apr 03, 2025 at 05:33:31PM +0800, 白烁冉 wrote:
> Dear Maintainers,
>
> When using our customized Syzkaller to fuzz the latest Linux kernel, the following crash (95th)was triggered.
>
>
> HEAD commit: 6537cfb395f352782918d8ee7b7f10ba2cc3cbf2
> git tree: upstream
> Output:https://github.com/pghk13/Kernel-Bug/tree/main/0305_6.14rc5/95-INFO_%20rcu%20detected%20stall%20in%20sys_chdir
> Kernel config:https://github.com/pghk13/Kernel-Bug/blob/main/0305_6.14rc5/config.txt
> C reproducer:https://github.com/pghk13/Kernel-Bug/blob/main/0305_6.14rc5/95-INFO_%20rcu%20detected%20stall%20in%20sys_chdir/95repro.c
> Syzlang reproducer: https://github.com/pghk13/Kernel-Bug/blob/main/0305_6.14rc5/95-INFO_%20rcu%20detected%20stall%20in%20sys_chdir/95call_trace.txt
We generally ignore any reports from non-official syzbot instances.
>
>
>
> Our reproducer uses mounts a constructed filesystem image.
> This could be a file system deadlock issue that occurs on lines
> 547-548 of the chmod_common function. When this function is called,
> the code already holds the inode lock (via the inode_lock (inode)),
> but the notify_change may need to perform RCU-protected operations
> internally. The core of the problem is that the chmod_common function
> calls the notify_change while holding the inode lock, and the
> notify_change internally relies on the RCU protection mechanism. At a
> specific path to the SYSV file system, this combination results in a
> deadlock.
I'm not following at all but also sysv is removed in v6.15.
prev parent reply other threads:[~2025-04-03 10:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-03 9:33 INFO: task hung in chmod_common 白烁冉
2025-04-03 10:30 ` Christian Brauner [this message]
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