Re: [PATCHv2] arch/arm/Kconfig: default ARM_MODULE_PLTS to 'y'

From: Russell King - ARM Linux
Date: Wed Jan 31 2018 - 15:25:28 EST


On Wed, Jan 31, 2018 at 09:19:11PM +0100, Anders Roxell wrote:
> While testing multi_v7_defconfig with LOCKDEP enabled, the kernel
> fails to load simple modules, as reported by kselftest:
>
> [ 34.107620] test_printf: section 4 reloc 2 sym 'memset': relocation
> 28 out of range (0xbf046044 -> 0xc109f720)
> selftests: printf.sh [FAIL]
>
> The problem that is seen when LOCKDEP is enabled without
> ARM_MODULE_PLTS, is that LOCKDEP eats so much memory that the top of the
> kernel gets out of reach from the bottom of the module area.

As I've said three times already (and clearly the message still hasn't
sunk in), it does _not_ follow that "enable lockdep" means "lots more
memory used". We could say the same thing about several other kernel
options as well. Please remove this from your commit message.

<exasperation at seemingly being ignored on this point>

Maybe you'd like to send your configuration file so we can see how much
is enabled in your kernel. At that point I'll make a decision, but
until then, I'm not going to say that even what I suggested is an
acceptable way forward.

>
> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
> ---
> arch/arm/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 51c8df561077..8014c8c322df 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1702,6 +1702,7 @@ config ARCH_WANT_GENERAL_HUGETLB
> config ARM_MODULE_PLTS
> bool "Use PLTs to allow module memory to spill over into vmalloc area"
> depends on MODULES
> + default y
> help
> Allocate PLTs when loading modules so that jumps and calls whose
> targets are too far away for their relative offsets to be encoded
> --
> 2.11.0
>

--
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