linux-kernel - Re: linux-next: boottime warning from todays linux-next

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Date:   Fri, 11 Feb 2022 12:33:36 +1100
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Tong Zhang <ztong0001@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Domenico Andreoli <domenico.andreoli@...ux.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: linux-next: boottime warning from todays linux-next

Hi Luis,

On Thu, 10 Feb 2022 15:19:09 -0800 Luis Chamberlain <mcgrof@...nel.org> wrote:
> 
> FWIW Linus merged a more newer version of the regression fix, and only
> until today did we get that version on linux-next.
> 
> > So it seems that the parent of "fs/binfmt_misc" is a permanently empty
> > directory - the is_empty_dir() check in insert_header() succeeds.  
> 
> I am not seeing this issue on x86_64 KVM guest with:
> 
> CONFIG_BINFMT_MISC=m
> or
> CONFIG_BINFMT_MISC=y
> 
> I think the issue might be that linux-next has Andrew's earlier
> version of the fix merged, and Linus now has the new version. So
> linux-next has these extra things below. But I can't understand
> why this is seen on ppc and not on x86_64.
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 241cfc6bc36f..788b9a34d5ab 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2735,17 +2735,6 @@ static struct ctl_table vm_table[] = {
>  	{ }
>  };
>  
> -static struct ctl_table fs_table[] = {
> -#if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE)
> -	{
> -		.procname	= "binfmt_misc",
> -		.mode		= 0555,
> -		.child		= sysctl_mount_point,
> -	},
> -#endif
> -	{ }
> -};
> -
>  static struct ctl_table debug_table[] = {
>  #ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
>  	{
> @@ -2765,7 +2754,6 @@ static struct ctl_table dev_table[] = {
>  
>  DECLARE_SYSCTL_BASE(kernel, kern_table);
>  DECLARE_SYSCTL_BASE(vm, vm_table);
> -DECLARE_SYSCTL_BASE(fs, fs_table);
>  DECLARE_SYSCTL_BASE(debug, debug_table);
>  DECLARE_SYSCTL_BASE(dev, dev_table);
>  
> @@ -2773,7 +2761,6 @@ int __init sysctl_init_bases(void)
>  {
>  	register_sysctl_base(kernel);
>  	register_sysctl_base(vm);
> -	register_sysctl_base(fs);
>  	register_sysctl_base(debug);
>  	register_sysctl_base(dev);
>  

Thanks for noticing that.  I have removed the old version from my copy
of mmotm today.

-- 
Cheers,
Stephen Rothwell

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