[Letux-kernel] 5.4-rc1 woes

Andreas Kemnade andreas at kemnade.info
Thu Oct 3 10:44:47 CEST 2019


On Thu, 3 Oct 2019 08:26:46 +0200
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> > Am 02.10.2019 um 23:16 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > 
> > On Wed, 2 Oct 2019 22:19:31 +0200
> > Andreas Kemnade <andreas at kemnade.info> wrote:
> > 
> > [..]  
> >> # first bad commit: [ac7c3e4ff401b304489a031938dbeaab585bfe0a] compiler: enable CONFIG_OPTIMIZE_INLINING forcibly
> >> 
> >> hmmmm...
> >> Now it depends on compliers?!
> >> andi at aktux:~/gta04/gta04-autotest-kernel$ arm-linux-gnueabihf-gcc --version
> >> arm-linux-gnueabihf-gcc (Debian 8.3.0-2) 8.3.0
> >> Copyright (C) 2018 Free Software Foundation, Inc.
> >> This is free software; see the source for copying conditions.  There is NO
> >> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> >> 
> >> And how to debug it? Well, lets first check whether reverting that
> >> improves things on 5.4-rc1.
> >>   
> > ok, tested to revert it: I had to disable it in .config afterwards,
> > seems to have crept into letux_defconfig.  
> 
> Was automatically set if undefined...
> 
> git show f863a359c2b2 | fgrep CONFIG_OPTIMIZE_INLINING
> -# CONFIG_OPTIMIZE_INLINING is not set
> +CONFIG_OPTIMIZE_INLINING=y
> 
> > And so weird error messages.  
> 
> Indeed.
> 
> > No bad addresses. I guess it somehow incfluences some copy_to_user
> > stuff.
> > Weird. So where to ask...?  
> 
> fgrep OPTIMIZE_INLINING -R *
> arch/arm/boot/src/FULLCONFIG:CONFIG_OPTIMIZE_INLINING=y
> arch/arm/configs/letux_defconfig:CONFIG_OPTIMIZE_INLINING=y
> arch/arm/configs/letux_defconfig.bak:CONFIG_OPTIMIZE_INLINING=y
> arch/arm/configs/letux_lpae_defconfig:CONFIG_OPTIMIZE_INLINING=y
> arch/arm/configs/letux_lpae_defconfig.bak:CONFIG_OPTIMIZE_INLINING=y
> arch/arm/configs/omap3_beagle_defconfig:# CONFIG_OPTIMIZE_INLINING is not set
> arch/mips/boot/src/CONFIG:# CONFIG_OPTIMIZE_INLINING is not set
> arch/mips/boot/src/FULLCONFIG:CONFIG_OPTIMIZE_INLINING=y
> arch/mips/configs/letux_defconfig:CONFIG_OPTIMIZE_INLINING=y
> arch/sparc/vdso/vdso32/vclock_gettime.c:#undef	CONFIG_OPTIMIZE_INLINING
> arch/x86/configs/i386_defconfig:CONFIG_OPTIMIZE_INLINING=y
> arch/x86/configs/x86_64_defconfig:CONFIG_OPTIMIZE_INLINING=y
> arch/x86/entry/vdso/vdso32/vclock_gettime.c:#undef CONFIG_OPTIMIZE_INLINING
> include/linux/compiler_types.h:#if !defined(CONFIG_OPTIMIZE_INLINING)
> kernel/configs/tiny.config:CONFIG_OPTIMIZE_INLINING=y
> lib/Kconfig.debug:config OPTIMIZE_INLINING
> 
> So it is defined in lib/Kconfig.debug. Do we still have debugging enabled?
> 
well, that Kconfig.debug is enabled unconditionally.

> Only minimally:
> 
> fgrep DEBUG arch/arm/configs/letux_defconfig | fgrep -v '#'
> CONFIG_DEBUG_FS=y
> CONFIG_HAVE_DEBUG_KMEMLEAK=y
> CONFIG_ARCH_HAS_DEBUG_VIRTUAL=y
> CONFIG_DEBUG_MEMORY_INIT=y
> CONFIG_LOCK_DEBUGGING_SUPPORT=y
> CONFIG_DEBUG_BUGVERBOSE=y
> CONFIG_DEBUG_LL_INCLUDE="mach/debug-macro.S"
> 
> It is used in only one place: include/linux/compiler-gcc.h
> 
> But why was it set automatically? Because the new patch forces it to be so...
> 
> > Weird.  
> 
> Indeed.
> 
> > So where to ask...?  
> 
> Author: Masahiro Yamada <yamada.masahiro at socionext.com>
> 
>     I am keeping the config option just in case any problem crops up for other
>     architectures.
> 
well, the answer is not so easy. That option is e.g. enabled on x86_64
debian buster kernels. So I am actually writing an email on a kernel
with that flag turned on.

So it must be a combination of CONFIGs which
trigger some bug in the code (probably arm-specific).
Maybe trying omap2plus_defconfig will be interesting.

It has not turned on CONFIG_PREEMPT.

Regards,
Andreas


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