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

From: Stephen Rothwell <[email-masked]>
Date: Thu, 10 Feb 2022 22:29:53 +1100

Hi all,

On Thu, 10 Feb 2022 21:41:25 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> On Thu, 10 Feb 2022 19:33:02 +1100 Stephen Rothwell <[email-masked]> wrote:
> >
> > On Thu, 10 Feb 2022 18:43:40 +1100 Stephen Rothwell <[email-masked]> wrote:  
> > >
> > > My qemu boot of a powerpc pseries_le_defconfig kernel produced these
> > > kernel messages:
> > > 
> > >   CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.0-rc3 #2
> > >   Call Trace:
> > >   [c0000000073e3a80] [c0000000007bfd40] dump_stack_lvl+0x74/0xa8 (unreliable)
> > >   [c0000000073e3ac0] [c00000000057e3dc] __register_sysctl_table+0x60c/0x9f0
> > >   [c0000000073e3bd0] [c000000002041170] init_fs_stat_sysctls+0x48/0x60
> > >   [c0000000073e3bf0] [c000000000012110] do_one_initcall+0x60/0x2d0
> > >   [c0000000073e3cd0] [c0000000020049f0] kernel_init_freeable+0x334/0x3dc
> > >   [c0000000073e3db0] [c000000000012710] kernel_init+0x30/0x1a0
> > >   [c0000000073e3e10] [c00000000000cd64] ret_from_kernel_thread+0x5c/0x64
> > > 
> > > Presumably introduced by commit
> > > 
> > >   b42bc9a3c511 ("Fix regression due to "fs: move binfmt_misc sysctl to its own file"")    
> > 
> > OK, I cannot reproduce this with just Linus' tree.  I will try to bisect.  
> 
> It bisected to commit
> 
>   43a9443d5da2 ("Merge branch 'akpm-current/current'")
> 
> and both parents of that commit are fine :-(

So it seems that the parent of "fs/binfmt_misc" is a permanently empty
directory - the is_empty_dir() check in insert_header() succeeds.
-- 
Cheers,
Stephen Rothwell