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Date:   Thu, 10 Feb 2022 22:29:53 +1100
From:   Stephen Rothwell <sfr@canb.auug.org.au>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Domenico Andreoli <domenico.andreoli@linux.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Tong Zhang <ztong0001@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>
Subject: Re: linux-next: boottime warning from todays linux-next
Message-ID: <20220210222953.6e078d20@canb.auug.org.au>
In-Reply-To: <20220210214125.2b248790@canb.auug.org.au>
References: <20220210184340.7eba108a@canb.auug.org.au>
        <20220210193302.686fa61a@canb.auug.org.au>
        <20220210214125.2b248790@canb.auug.org.au>
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Hi all,

On Thu, 10 Feb 2022 21:41:25 +1100 Stephen Rothwell <sfr@canb.auug.org.au> =
wrote:
>
> On Thu, 10 Feb 2022 19:33:02 +1100 Stephen Rothwell <sfr@canb.auug.org.au=
> wrote:
> >
> > On Thu, 10 Feb 2022 18:43:40 +1100 Stephen Rothwell <sfr@canb.auug.org.=
au> wrote: =20
> > >
> > > My qemu boot of a powerpc pseries_le_defconfig kernel produced these
> > > kernel messages:
> > >=20
> > >   CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.0-rc3 #2
> > >   Call Trace:
> > >   [c0000000073e3a80] [c0000000007bfd40] dump_stack_lvl+0x74/0xa8 (unr=
eliable)
> > >   [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+0x334/0x=
3dc
> > >   [c0000000073e3db0] [c000000000012710] kernel_init+0x30/0x1a0
> > >   [c0000000073e3e10] [c00000000000cd64] ret_from_kernel_thread+0x5c/0=
x64
> > >=20
> > > Presumably introduced by commit
> > >=20
> > >   b42bc9a3c511 ("Fix regression due to "fs: move binfmt_misc sysctl t=
o its own file"")   =20
> >=20
> > OK, I cannot reproduce this with just Linus' tree.  I will try to bisec=
t. =20
>=20
> It bisected to commit
>=20
>   43a9443d5da2 ("Merge branch 'akpm-current/current'")
>=20
> 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.
--=20
Cheers,
Stephen Rothwell

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