* [PATCH] mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly
@ 2016-05-23 16:54 Yang Shi
2016-05-23 18:22 ` Michal Hocko
0 siblings, 1 reply; 3+ messages in thread
From: Yang Shi @ 2016-05-23 16:54 UTC (permalink / raw)
To: akpm, mhocko; +Cc: linux-kernel, linux-mm, linaro-kernel, yang.shi
Per the suggestion from Michal Hocko [1], CONFIG_DEFERRED_STRUCT_PAGE_INIT
should be incompatible with FLATMEM, make this explicitly in Kconfig.
[1] http://lkml.kernel.org/r/20160523073157.GD2278@dhcp22.suse.cz
Signed-off-by: Yang Shi <yang.shi@linaro.org>
---
mm/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/Kconfig b/mm/Kconfig
index 2664c11..22fa818 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -649,6 +649,7 @@ config DEFERRED_STRUCT_PAGE_INIT
default n
depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
depends on MEMORY_HOTPLUG
+ depends on !FLATMEM
help
Ordinarily all struct pages are initialised during early boot in a
single thread. On very large machines this can take a considerable
--
2.0.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly
2016-05-23 16:54 [PATCH] mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly Yang Shi
@ 2016-05-23 18:22 ` Michal Hocko
2016-05-23 18:35 ` Shi, Yang
0 siblings, 1 reply; 3+ messages in thread
From: Michal Hocko @ 2016-05-23 18:22 UTC (permalink / raw)
To: Yang Shi; +Cc: akpm, linux-kernel, linux-mm, linaro-kernel
On Mon 23-05-16 09:54:31, Yang Shi wrote:
> Per the suggestion from Michal Hocko [1], CONFIG_DEFERRED_STRUCT_PAGE_INIT
> should be incompatible with FLATMEM, make this explicitly in Kconfig.
I guess the changelog could benefit from some clarification. What
do you think about the following:
"
DEFERRED_STRUCT_PAGE_INIT requires some ordering wrt other
initialization operations, e.g. page_ext_init has to happen after the
whole memmap is initialized properly. For SPARSEMEM this requires to
wait for page_alloc_init_late. Other memory models (e.g. flatmem) might
have different initialization layouts (page_ext_init_flatmem). Currently
DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which in turn
depends on SPARSEMEM || X86_64_ACPI_NUMA
depends on ARCH_ENABLE_MEMORY_HOTPLUG
and X86_64_ACPI_NUMA depends on NUMA which in turn disable FLATMEM
memory model:
config ARCH_FLATMEM_ENABLE
def_bool y
depends on X86_32 && !NUMA
so FLATMEM is ruled out via dependency maze. Be explicit and disable
FLATMEM for DEFERRED_STRUCT_PAGE_INIT so that we do not reintroduce
subtle initialization bugs
"
>
> [1] http://lkml.kernel.org/r/20160523073157.GD2278@dhcp22.suse.cz
>
> Signed-off-by: Yang Shi <yang.shi@linaro.org>
> ---
> mm/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 2664c11..22fa818 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -649,6 +649,7 @@ config DEFERRED_STRUCT_PAGE_INIT
> default n
> depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
> depends on MEMORY_HOTPLUG
> + depends on !FLATMEM
> help
> Ordinarily all struct pages are initialised during early boot in a
> single thread. On very large machines this can take a considerable
> --
> 2.0.2
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly
2016-05-23 18:22 ` Michal Hocko
@ 2016-05-23 18:35 ` Shi, Yang
0 siblings, 0 replies; 3+ messages in thread
From: Shi, Yang @ 2016-05-23 18:35 UTC (permalink / raw)
To: Michal Hocko; +Cc: akpm, linux-kernel, linux-mm, linaro-kernel
On 5/23/2016 11:22 AM, Michal Hocko wrote:
> On Mon 23-05-16 09:54:31, Yang Shi wrote:
>> Per the suggestion from Michal Hocko [1], CONFIG_DEFERRED_STRUCT_PAGE_INIT
>> should be incompatible with FLATMEM, make this explicitly in Kconfig.
>
> I guess the changelog could benefit from some clarification. What
> do you think about the following:
>
> "
> DEFERRED_STRUCT_PAGE_INIT requires some ordering wrt other
> initialization operations, e.g. page_ext_init has to happen after the
> whole memmap is initialized properly. For SPARSEMEM this requires to
> wait for page_alloc_init_late. Other memory models (e.g. flatmem) might
> have different initialization layouts (page_ext_init_flatmem). Currently
> DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which in turn
> depends on SPARSEMEM || X86_64_ACPI_NUMA
> depends on ARCH_ENABLE_MEMORY_HOTPLUG
>
> and X86_64_ACPI_NUMA depends on NUMA which in turn disable FLATMEM
> memory model:
> config ARCH_FLATMEM_ENABLE
> def_bool y
> depends on X86_32 && !NUMA
>
> so FLATMEM is ruled out via dependency maze. Be explicit and disable
> FLATMEM for DEFERRED_STRUCT_PAGE_INIT so that we do not reintroduce
> subtle initialization bugs
> "
Thanks a lot. It sounds way better. Will address in V2.
Yang
>
>>
>> [1] http://lkml.kernel.org/r/20160523073157.GD2278@dhcp22.suse.cz
>>
>> Signed-off-by: Yang Shi <yang.shi@linaro.org>
>> ---
>> mm/Kconfig | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index 2664c11..22fa818 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>> @@ -649,6 +649,7 @@ config DEFERRED_STRUCT_PAGE_INIT
>> default n
>> depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
>> depends on MEMORY_HOTPLUG
>> + depends on !FLATMEM
>> help
>> Ordinarily all struct pages are initialised during early boot in a
>> single thread. On very large machines this can take a considerable
>> --
>> 2.0.2
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-05-23 16:54 [PATCH] mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly Yang Shi
2016-05-23 18:22 ` Michal Hocko
2016-05-23 18:35 ` Shi, Yang
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