linux-kernel - Re: dcache_readdir NULL inode oops

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Message-ID: <20181109155856.GC2091@brain-police>
Date:   Fri, 9 Nov 2018 15:58:56 +0000
From:   Will Deacon <will.deacon@....com>
To:     Jan Glauber <Jan.Glauber@...ium.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: dcache_readdir NULL inode oops

On Fri, Nov 09, 2018 at 02:37:51PM +0000, Jan Glauber wrote:
> I'm seeing the following oops reproducible with upstream kernel on arm64
> (ThunderX2):

[...]

> It happens after 1-3 hours of running 'stress-ng --dev 128'. This testcase
> does a scandir of /dev and then calls random stuff like ioctl, lseek,
> open/close etc. on the entries. I assume no files are deleted under /dev
> during the testcase.
> 
> The NULL pointer is the inode pointer of next. The next dentry->d_flags is
> DCACHE_RCUACCESS when this happens.
> 
> Any hints on how to further debug this?

Can you reproduce the issue with vanilla -rc1 and do you have a "known good"
kernel?

Will