[PATCH] mm: Generalize HUGETLB_PAGE_SIZE_VARIABLE

[PATCH] mm: Generalize HUGETLB_PAGE_SIZE_VARIABLE

[Anshuman Khandual]

HUGETLB_PAGE_SIZE_VARIABLE need not be defined for each individual
platform subscribing it. Instead just make it generic.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
This change was originally suggested in an earilier discussion. This
applies on v5.12-rc1 and has been build tested on all applicable
platforms i.e ia64 and powerpc.

https://patchwork.kernel.org/project/linux-mm/patch/1613024531-19040-3-git-send-email-anshuman.khandual@arm.com/

 arch/ia64/Kconfig    | 6 +-----
 arch/powerpc/Kconfig | 6 +-----
 mm/Kconfig           | 8 ++++++++
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 2ad7a8d29fcc..6b3e3f6c29ae 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -32,6 +32,7 @@ config IA64
 	select TTY
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_VIRT_CPU_ACCOUNTING
+	select HUGETLB_PAGE_SIZE_VARIABLE
 	select VIRT_TO_BUS
 	select GENERIC_IRQ_PROBE
 	select GENERIC_PENDING_IRQ if SMP
@@ -82,11 +83,6 @@ config STACKTRACE_SUPPORT
 config GENERIC_LOCKBREAK
 	def_bool n
 
-config HUGETLB_PAGE_SIZE_VARIABLE
-	bool
-	depends on HUGETLB_PAGE
-	default y
-
 config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3778ad17f56a..b8565bed284f 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -232,6 +232,7 @@ config PPC
 	select HAVE_HARDLOCKUP_DETECTOR_PERF	if PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HUGETLB_PAGE_SIZE_VARIABLE	if PPC_BOOK3S_64
 	select MMU_GATHER_RCU_TABLE_FREE
 	select MMU_GATHER_PAGE_SIZE
 	select HAVE_REGS_AND_STACK_ACCESS_API
@@ -416,11 +417,6 @@ config HIGHMEM
 
 source "kernel/Kconfig.hz"
 
-config HUGETLB_PAGE_SIZE_VARIABLE
-	bool
-	depends on HUGETLB_PAGE && PPC_BOOK3S_64
-	default y
-
 config MATH_EMULATION
 	bool "Math emulation"
 	depends on 4xx || PPC_8xx || PPC_MPC832x || BOOKE
diff --git a/mm/Kconfig b/mm/Kconfig
index 24c045b24b95..e604a87862a4 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -274,6 +274,14 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
 config ARCH_ENABLE_THP_MIGRATION
 	bool
 
+config HUGETLB_PAGE_SIZE_VARIABLE
+	def_bool n
+	depends on HUGETLB_PAGE
+	help
+	  When there are multiple HugeTLB sizes available on a platform
+	  and pageblock_order could then be a dynamic value instead of
+	  standard HUGETLB_PAGE_ORDER.
+
 config CONTIG_ALLOC
 	def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
 
-- 
2.20.1

Re: [PATCH] mm: Generalize HUGETLB_PAGE_SIZE_VARIABLE

[Christoph Hellwig]

On Mon, Mar 01, 2021 at 11:20:53AM +0530, Anshuman Khandual wrote:
> HUGETLB_PAGE_SIZE_VARIABLE need not be defined for each individual
> platform subscribing it. Instead just make it generic.
> 
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: linux-ia64@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> This change was originally suggested in an earilier discussion. This
> applies on v5.12-rc1 and has been build tested on all applicable
> platforms i.e ia64 and powerpc.
> 
> https://patchwork.kernel.org/project/linux-mm/patch/1613024531-19040-3-git-send-email-anshuman.khandual@arm.com/
> 
>  arch/ia64/Kconfig    | 6 +-----
>  arch/powerpc/Kconfig | 6 +-----
>  mm/Kconfig           | 8 ++++++++
>  3 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
> index 2ad7a8d29fcc..6b3e3f6c29ae 100644
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -32,6 +32,7 @@ config IA64
>  	select TTY
>  	select HAVE_ARCH_TRACEHOOK
>  	select HAVE_VIRT_CPU_ACCOUNTING
> +	select HUGETLB_PAGE_SIZE_VARIABLE

doesn't this need a 'if HUGETLB_PAGE'

or did you verify that HUGETLB_PAGE_SIZE_VARIABLE checks are always
nested inside of HUGETLB_PAGE ones?

Re: [PATCH] mm: Generalize HUGETLB_PAGE_SIZE_VARIABLE

[Anshuman Khandual]

On 3/1/21 11:53 AM, Christoph Hellwig wrote:
> On Mon, Mar 01, 2021 at 11:20:53AM +0530, Anshuman Khandual wrote:
>> HUGETLB_PAGE_SIZE_VARIABLE need not be defined for each individual
>> platform subscribing it. Instead just make it generic.
>>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Christoph Hellwig <hch@lst.de>
>> Cc: linux-ia64@vger.kernel.org
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Cc: linux-mm@kvack.org
>> Cc: linux-kernel@vger.kernel.org
>> Suggested-by: Christoph Hellwig <hch@lst.de>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> This change was originally suggested in an earilier discussion. This
>> applies on v5.12-rc1 and has been build tested on all applicable
>> platforms i.e ia64 and powerpc.
>>
>> https://patchwork.kernel.org/project/linux-mm/patch/1613024531-19040-3-git-send-email-anshuman.khandual@arm.com/
>>
>>  arch/ia64/Kconfig    | 6 +-----
>>  arch/powerpc/Kconfig | 6 +-----
>>  mm/Kconfig           | 8 ++++++++
>>  3 files changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
>> index 2ad7a8d29fcc..6b3e3f6c29ae 100644
>> --- a/arch/ia64/Kconfig
>> +++ b/arch/ia64/Kconfig
>> @@ -32,6 +32,7 @@ config IA64
>>  	select TTY
>>  	select HAVE_ARCH_TRACEHOOK
>>  	select HAVE_VIRT_CPU_ACCOUNTING
>> +	select HUGETLB_PAGE_SIZE_VARIABLE
> 
> doesn't this need a 'if HUGETLB_PAGE'

While making HUGETLB_PAGE_SIZE_VARIABLE a generic option, also made it
dependent on HUGETLB_PAGE. Should not that gate HUGETLB_PAGE_SIZE_VARIABLE
when HUGETLB_PAGE is not available irrespective of the select statement on
the platforms ?

> 
> or did you verify that HUGETLB_PAGE_SIZE_VARIABLE checks are always
> nested inside of HUGETLB_PAGE ones?
>

Re: [PATCH] mm: Generalize HUGETLB_PAGE_SIZE_VARIABLE

[Christoph Hellwig]

On Mon, Mar 01, 2021 at 01:13:41PM +0530, Anshuman Khandual wrote:
> > doesn't this need a 'if HUGETLB_PAGE'
> 
> While making HUGETLB_PAGE_SIZE_VARIABLE a generic option, also made it
> dependent on HUGETLB_PAGE. Should not that gate HUGETLB_PAGE_SIZE_VARIABLE
> when HUGETLB_PAGE is not available irrespective of the select statement on
> the platforms ?

depends doesn't properly work for variables that are selected.

Re: [PATCH] mm: Generalize HUGETLB_PAGE_SIZE_VARIABLE

[Anshuman Khandual]

On 3/1/21 1:23 PM, Christoph Hellwig wrote:
> On Mon, Mar 01, 2021 at 01:13:41PM +0530, Anshuman Khandual wrote:
>>> doesn't this need a 'if HUGETLB_PAGE'
>>
>> While making HUGETLB_PAGE_SIZE_VARIABLE a generic option, also made it
>> dependent on HUGETLB_PAGE. Should not that gate HUGETLB_PAGE_SIZE_VARIABLE
>> when HUGETLB_PAGE is not available irrespective of the select statement on
>> the platforms ?
> 
> depends doesn't properly work for variables that are selected.
> 

Alright, will move the HUGETLB_PAGE dependency to platforms while selecting
the variable HUGETLB_PAGE_SIZE_VARIABLE.