On Fri, Nov 4, 2022 at 3:15 PM Sven Schwermer <[email protected]> wrote:
>
> Hi again,
>
> I played around a little and it seems like the following patch fixes the
> issue. It may be related to the following series, marking some of these
> functions __init:
> https://patchwork.kernel.org/project/linux-fsdevel/list/?series=325591&state=%2A&archive=both
>
That does look very likely.
Since I wasn't seeing the same issue as you are, would you like to add
your Signed-off-by
and send the patch ? I can then queue it for regression testing.
Bruce
> diff --git a/init/main.c b/init/main.c
> index f141c69186bf..13df9fb8855e 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1573,14 +1573,13 @@ static int __ref kernel_init(void *unused)
> void __init console_on_rootfs(void)
> {
> #ifndef CONFIG_BLK_DEV_INITRD
> - /*
> - * Use /dev/console to infer if the rootfs is setup properly.
> - * In case of initrd or initramfs /dev/console might be instantiated
> - * later by /init so don't do this check for CONFIG_BLK_DEV_INITRD
> - */
> - struct kstat console_stat;
> - if (vfs_lstat((char __user *) "/dev/console", (struct kstat __user *)
> &console_stat)
> - || !S_ISCHR(console_stat.mode)) {
> + /*
> + * Use /dev/console to infer if the rootfs is setup properly.
> + * In case of initrd or initramfs /dev/console might be instantiated
> + * later by /init so don't do this check for CONFIG_BLK_DEV_INITRD
> + */
> + struct kstat stat;
> + if (init_stat("/dev/console", &stat, 0) || !S_ISCHR(stat.mode)) {
> panic("/dev/console is missing or not a character
> device!\nPlease
> ensure your rootfs is properly configured\n");
> }
> #endif
>
>
> On 11/4/22 14:22, Bruce Ashfield wrote:
> >
> >
> > On Fri, Nov 4, 2022 at 6:30 AM Sven Schwermer <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > Hi,
> >
> > We're in the process of migrating from dunfell to kirkstone and noticed
> > a regression with the Linux kernel (branch: v5.15/standard/base). The
> > boot panics with
> >
> > [ 1.038015] Kernel panic - not syncing: /dev/console is missing!
> > [ 1.038015] Please ensure your rootfs is properly configured
> >
> > I have bisected the revisions between the good dunfell one and the bad
> > kirkstone one and the offending commit is:
> >
> > 0d7260ad7106 check console device file on fs when booting
> >
> >
> > the commit itself hasn't changed between those releases and kernel
> > versions, so it very well could be something else in the kernel or in
> > the generation of the rootfs that is now triggering the commit to change.
> >
> > The logic for the change is documented in the patch itself. We were
> > getting a lot (5 or more a week) questions (and blaming of the
> > kernel) when badly created rootfs were being booted. They all had
> > mangled /dev/console devices, and fixing that, fixed the boot. It was
> > much easier to just check and fail with a clearer message than the
> > other issues that happen down the boot process and that are much
> > more cryptic to debug.
> >
> > The weird thing is that vfs_lstat() fails while the subsequent
> > filp_open() in on the same file succeeds. I'm booting without
> > initramfs/initrd and with automounted devtmpfs:
> >
> > CONFIG_DEVTMPFS=y
> > CONFIG_DEVTMPFS_MOUNT=y
> > # CONFIG_BLK_DEV_INITRD is not set
> >
> > Since this commit is not part of upstream Linux, I thought I'd ask for
> > help here. What's the purpose of this extra check and why is it failing
> > even though /dev/console exists (filp_open("dev/console") works)?
> >
> >
> > That same check isn't failing in anything I've run, or the release process
> > has run (but a non initrd boot isn't as common, so it isn't impossible that
> > something slipped through).
> >
> > If there's a set of public layers that I can use to reproduce the problem,
> > I can have a closer look. But it will be just me digging into the vfs_lstat
> > call to see if we are now misinterpreting the return from the routine, etc.
> >
> > Bruce
> >
> >
> > Best regards,
> > Sven
> >
> >
> >
> > --
> > - Thou shalt not follow the NULL pointer, for chaos and madness await
> > thee at its end
> > - "Use the force Harry" - Gandalf, Star Trek II
> >
--
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II
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