linux-kernel - Re: [GIT PULL] remove ksys_mount() and ksys

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Date:   Tue, 17 Dec 2019 12:40:07 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Jesse Barnes <jsbarnes@...gle.com>
Cc:     Dominik Brodowski <linux@...inikbrodowski.net>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] remove ksys_mount() and ksys_dup()

On Tue, Dec 17, 2019 at 11:33 AM Jesse Barnes <jsbarnes@...gle.com> wrote:
>
> Still debugging, but this causes a panic in console_on_rootfs() when we try to dup the fds for stderr and stdout.

Duh.

That series was incredibly buggy, and there's another bug in there.

I think this should fix it:

  diff --git a/init/main.c b/init/main.c
  index ec3a1463ac69..1ecfd43ed464 100644
  --- a/init/main.c
  +++ b/init/main.c
  @@ -1163,7 +1163,7 @@ void console_on_rootfs(void)

          /* Open /dev/console in kernelspace, this should never fail */
          file = filp_open("/dev/console", O_RDWR, 0);
  -       if (!file)
  +       if (IS_ERR(file))
                  goto err_out;

          /* create stdin/stdout/stderr, this should never fail */

and yes,that particular problem only triggers when you have some odd
root filesystem without a /dev/console. Or a kernel config that
doesn't have those devices enabled at all.

I delayed pulling it for a couple of days, but the branch was not in
linux-next, so my delay didn't make any difference, and all these
things only became obvious after I pulled. And while it was all
horribly buggy, it was only buggy for the "these cases don't happen in
a normal distro" case, so the regular use didn't show them.

My bad. I shouldn't have pulled this, but it all looked very obvious
and trivial.

              Linus