linux-kernel - Re: [LKP] [ide] ec7d9c9ce8: WARNING:at_fs/proc/generic.c:#remove_proc_entry

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Message-ID: <20181221015352.GA7734@intel.com>
Date:   Fri, 21 Dec 2018 09:53:52 +0800
From:   Philip Li <philip.li@...el.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     kernel test robot <lkp@...el.com>, Christoph Hellwig <hch@....de>,
        David Miller <davem@...emloft.net>, linux-ide@...r.kernel.org,
        lkp@...org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [LKP] [ide] ec7d9c9ce8:
 WARNING:at_fs/proc/generic.c:#remove_proc_entry

On Thu, Dec 20, 2018 at 08:05:28AM -0800, Linus Torvalds wrote:
> On Thu, Dec 20, 2018 at 1:19 AM kernel test robot <lkp@...el.com> wrote:
> >
> > FYI, we noticed the following commit (built with gcc-7):
> >
> > commit: ec7d9c9ce897174243af4fcd201dbfc34df0f3a3 ("ide: replace ->proc_fops with ->proc_show")
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> Funky.  How did the kernel test robot suddenly figure out an 8-month
> old problem?
Hi Linus, sorry for this late report. I can't figure out exact reason but some possible clues.

The issue is captured by rcutoture which doesn't work well before. And only from late october,
we have solved a few issues of the execution including the rootfs (yocto) it is using. And this issue
is against an randconfig, i'm not sure whether the issue depends on a certain kconfig thus only
be triggered or successfully bisected this time.

> 
> > [   44.180514] WARNING: CPU: 1 PID: 165 at fs/proc/generic.c:662 remove_proc_entry+0xb9/0x155
> 
> This is a warning for somebody doing "remove_proc_entry() on a name
> that doesn't actually exist in that /proc directory.
> 
> In this case, it does seem to be due to the named commit adding a
> 
> +               remove_proc_entry("settings", drive->proc);
> 
> to ide_proc_unregister_device(), and looking at the patch I get the
> feeling that it's due to a typo: the code *creates* the file called
> "setting", but removes the file "settings". Note the missing "s" at
> creation time.
> 
> And yes, the name of the /proc file _should_be "settings", judging by
> the rest of the patch.
> 
> So it does seem to be a real bug. Nobody noticed until now? Why did
> the test robot suddenly react to it?
> 
>               Linus
> _______________________________________________
> LKP mailing list
> LKP@...ts.01.org
> https://lists.01.org/mailman/listinfo/lkp

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