Re: BUG: unable to handle page fault for address - EIP: __kmap_local_page_prot

[Naresh Kamboju]

On Thu, 20 May 2021 at 00:20, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> On Wed, May 19 2021 at 20:38, Naresh Kamboju wrote:
> > While running LTP mm test suite on i386 kernel the following warning and BUG
> > reported on linux next 5.13.0-rc2-next-20210519.
> >
> > The warning is not regression, We have been noticing these warnings often on
> > i386
>
> Noticing? Did you report them?

I have reported this,

https://lore.kernel.org/linux-mm/CA+G9fYt+6OeibZMD0fP=O3nqFbcN3O4xcLkjq0mpQbZJ2uxB9w@xxxxxxxxxxxxxx/

>
> > but kernel BUG: looks to be a new crash.
>
> It's just the consequence of the problem which is pointed out by the
> warning. Fix below.

The below patch did not solve the reported problem.
after applying this patch
CONFIG_HAVE_MOVE_PUD
disappeared from the config.
but still i see WARNING: and BUG: when running LTP mm tests.

Test log link,
FYI,
i386 kernel Image running on x86_64 machine.
https://lkft.validation.linaro.org/scheduler/job/2749690#L10139


> Thanks,
>
>         tglx
> ---
> Subject: x86: Don't enable CONFIG_MOVE_PUD for 32bit and !PAE
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Date: Wed, 19 May 2021 20:37:34 +0200
>
> MOVE_PUD cannot work for 2-level paging obviously.
>
> Fixes: be37c98d1134 ("x86: mremap speedup - Enable HAVE_MOVE_PUD")
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>  arch/x86/Kconfig |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -219,7 +219,7 @@ config X86
>         select HAVE_MIXED_BREAKPOINTS_REGS
>         select HAVE_MOD_ARCH_SPECIFIC
>         select HAVE_MOVE_PMD
> -       select HAVE_MOVE_PUD
> +       select HAVE_MOVE_PUD                    if PGTABLE_LEVELS > 2
>         select HAVE_NMI
>         select HAVE_OPTPROBES
>         select HAVE_PCSPKR_PLATFORM

- Naresh