Re: [PATCH -next] init/main: Init jump_labels before they are used to build zonelists

Re: [PATCH -next] init/main: Init jump_labels before they are used to build zonelists

[Vlastimil Babka]

On 01/17/2017 09:49 PM, Vlastimil Babka wrote:
> On 17.1.2017 21:34, Andrew Morton wrote:
>>>>
>>>> Will you be able to look into that? Openrisc doesnt have jump_label
>>>> support, so its no issue at the moment.
>>>>
>>>> Archs that do have it:
>>>>
>>>> arch/arm64/Kconfig:     select HAVE_ARCH_JUMP_LABEL
>>>> arch/mips/Kconfig:      select HAVE_ARCH_JUMP_LABEL
>>>> arch/s390/Kconfig:      select HAVE_ARCH_JUMP_LABEL
>>>> arch/sparc/Kconfig:     select HAVE_ARCH_JUMP_LABEL if SPARC64
>>>> arch/tile/Kconfig:      select HAVE_ARCH_JUMP_LABEL
>>>> arch/x86/Kconfig:       select HAVE_ARCH_JUMP_LABEL
>>>> arch/arm/Kconfig:       select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
>>>> arch/powerpc/Kconfig:   select HAVE_ARCH_JUMP_LABEL
>>>>
>>>> I looked at a few (arm, tile) and I dont see their arch_jump_label_transform*
>>>> implementations depending on global state like ideal_nops from x86. They
>>>> should be ok.
>>>
>>> Thanks, I'll try.
>>>
>>>> If no time, Should you change your patch to not use static keys for
>>>> build_all_zonelists at least?
>>>
>>> Yes that would be uglier but possible if I find issues or I'm not
>>> confident enough with the auditing...
>>
>> We could just revert f5adbdff6a1c40e19 ("mm, page_alloc: convert
>> page_group_by_mobility_disable to static key")?
> 
> That's a -next commit id, as the patch is in mmotm. I'll ask for removal if I
> don't have a fix soon, but if you or somebody else prefers to do that ASAP, it
> can be re-added later with a fix.

OK I think that we just drop the patch [1] from mmotm. Mel told me the
benefit was marginal, and also the last move of jump_label_init() caused
problems for several releases.

Thanks,
Vlastimil

[1] mm-page_alloc-convert-page_group_by_mobility_disable-to-static-key.patch

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Re: [PATCH -next] init/main: Init jump_labels before they are used to build zonelists

[Mel Gorman]

On Thu, Jan 19, 2017 at 09:28:28AM +0100, Vlastimil Babka wrote:
> On 01/17/2017 09:49 PM, Vlastimil Babka wrote:
> > On 17.1.2017 21:34, Andrew Morton wrote:
> >>>>
> >>>> Will you be able to look into that? Openrisc doesnt have jump_label
> >>>> support, so its no issue at the moment.
> >>>>
> >>>> Archs that do have it:
> >>>>
> >>>> arch/arm64/Kconfig:     select HAVE_ARCH_JUMP_LABEL
> >>>> arch/mips/Kconfig:      select HAVE_ARCH_JUMP_LABEL
> >>>> arch/s390/Kconfig:      select HAVE_ARCH_JUMP_LABEL
> >>>> arch/sparc/Kconfig:     select HAVE_ARCH_JUMP_LABEL if SPARC64
> >>>> arch/tile/Kconfig:      select HAVE_ARCH_JUMP_LABEL
> >>>> arch/x86/Kconfig:       select HAVE_ARCH_JUMP_LABEL
> >>>> arch/arm/Kconfig:       select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
> >>>> arch/powerpc/Kconfig:   select HAVE_ARCH_JUMP_LABEL
> >>>>
> >>>> I looked at a few (arm, tile) and I dont see their arch_jump_label_transform*
> >>>> implementations depending on global state like ideal_nops from x86. They
> >>>> should be ok.
> >>>
> >>> Thanks, I'll try.
> >>>
> >>>> If no time, Should you change your patch to not use static keys for
> >>>> build_all_zonelists at least?
> >>>
> >>> Yes that would be uglier but possible if I find issues or I'm not
> >>> confident enough with the auditing...
> >>
> >> We could just revert f5adbdff6a1c40e19 ("mm, page_alloc: convert
> >> page_group_by_mobility_disable to static key")?
> > 
> > That's a -next commit id, as the patch is in mmotm. I'll ask for removal if I
> > don't have a fix soon, but if you or somebody else prefers to do that ASAP, it
> > can be re-added later with a fix.
> 
> OK I think that we just drop the patch [1] from mmotm. Mel told me the
> benefit was marginal, and also the last move of jump_label_init() caused
> problems for several releases.
> 

Note that it's not guaranteed to cause any problems this time. If
jump_label_init can go ahead without the page allocator being fully up
and running then it may be ok.

-- 
Mel Gorman
SUSE Labs

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