Re: [PATCH] mm/Kconfig: add MMU dependency for MIGRATION.

[Chen Gang F T <chen.gang.flying.transformer@gmail.com>]

On 08/05/2013 05:05 PM, Michal Hocko wrote:
> On Mon 05-08-13 11:03:01, Michal Hocko wrote:
>> > On Mon 05-08-13 16:46:14, Chen Gang F T wrote:
>>> > > On 08/05/2013 03:32 PM, Michal Hocko wrote:
>>>> > > > On Thu 01-08-13 10:39:57, Chen Gang wrote:
>>>>> > > >> MIGRATION need depend on MMU, or allmodconfig for sh architecture which
>>>>> > > >> without MMU will be fail for compiling.
>>>>> > > >>
>>>>> > > >> The related error: 
>>>>> > > >>
>>>>> > > >>     CC      mm/migrate.o
>>>>> > > >>   mm/migrate.c: In function 'remove_migration_pte':
>>>>> > > >>   mm/migrate.c:134:3: error: implicit declaration of function 'pmd_trans_huge' [-Werror=implicit-function-declaration]
>>>>> > > >>      if (pmd_trans_huge(*pmd))
>>>>> > > >>      ^
>>>>> > > >>   mm/migrate.c:149:2: error: implicit declaration of function 'is_swap_pte' [-Werror=implicit-function-declaration]
>>>>> > > >>     if (!is_swap_pte(pte))
>>>>> > > >>     ^
>>>>> > > >>   ...
>>>>> > > >>
>>>>> > > >>
>>>>> > > >> Signed-off-by: Chen Gang <gang.chen@asianux.com>
>>>>> > > >> ---
>>>>> > > >>  mm/Kconfig |    4 ++--
>>>>> > > >>  1 files changed, 2 insertions(+), 2 deletions(-)
>>>>> > > >>
>>>>> > > >> diff --git a/mm/Kconfig b/mm/Kconfig
>>>>> > > >> index 256bfd0..e847f19 100644
>>>>> > > >> --- a/mm/Kconfig
>>>>> > > >> +++ b/mm/Kconfig
>>>>> > > >> @@ -245,7 +245,7 @@ config COMPACTION
>>>>> > > >>  config MIGRATION
>>>>> > > >>  	bool "Page migration"
>>>>> > > >>  	def_bool y
>>>>> > > >> -	depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA
>>>>> > > >> +	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
>>>>> > > >>  	help
>>>>> > > >>  	  Allows the migration of the physical location of pages of processes
>>>>> > > >>  	  while the virtual addresses are not changed. This is useful in
>>>>> > > >> @@ -522,7 +522,7 @@ config MEM_SOFT_DIRTY
>>>>> > > >>  
>>>>> > > >>  config CMA
>>>>> > > >>  	bool "Contiguous Memory Allocator"
>>>>> > > >> -	depends on HAVE_MEMBLOCK
>>>>> > > >> +	depends on HAVE_MEMBLOCK && MMU
>>>> > > > 
>>>> > > > Why CMA has to depend on MMU as well? The MIGRATION part should be
>>>> > > > sufficient.
>>>> > > > 
>>> > > 
>>> > > MIGRATION need depend on MMU, when NOMMU, if select CMA, it will select
>>> > > MIGRATION by force.
>> > 
>> > Ohh, I wasn't aware of this Kcofing limitation. You are right then and
>> > CMA needs a dependency as well.

OK, thanks.

Every member may make mistakes (e.g. me), although we should try to
avoid to make mistakes (at least, every member don't want to make
mistakes by themselves ).

> Could you mention this in the changelog please.
> Feel free to add
> Reviewed-by: Michal Hocko <mhocko@suse.cz>
> 

OK, thanks, I will do.


>>> > > e.g. for allmodconfig with sh architecture, if we only let MIGRATION
>>> > > depend on MMU, not let CMA depend on MMU, it will report the warning
>>> > > below:
>>> > > 
>>> > >   scripts/kconfig/conf --allmodconfig Kconfig
>>> > >   warning: (COMPACTION && CMA) selects MIGRATION which has unmet direct dependencies ((NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU)
>>> > > 
>>> > > And for the final config file, MIGRATION is still enabled, although MMU
>>> > > is not defined.
>>> > > 
>>> > > 
>>>>> > > >>  	select MIGRATION
>>>>> > > >>  	select MEMORY_ISOLATION
>>>>> > > >>  	help
>>>> > > > 
>>> > > 
>>> > > Thanks.
>>> > > -- 
>>> > > Chen Gang
>>> > > 
>>> > > --
>>> > > To unsubscribe, send a message with 'unsubscribe linux-mm' in
>>> > > the body to majordomo@kvack.org.  For more info on Linux MM,
>>> > > see: http://www.linux-mm.org/ .
>>> > > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>> > 
>> > -- 
>> > Michal Hocko
>> > SUSE Labs
>> > 
>> > --
>> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> > the body to majordomo@kvack.org.  For more info on Linux MM,
>> > see: http://www.linux-mm.org/ .
>> > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> -- Michal Hocko SUSE Labs
> 


-- 
Chen Gang

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