[PATCH v4 0/2] arm64/hugetlb: enable gigantic page

changelog
=========
v3->v4:
add changelog in the cover leter to make the change history more clear.

v2->v3:
change the Kconfig file to avoid comile warning when select
ARCH_HAS_GIGANTIC_PAGE with !CONFIG_HUGETLB_PAGE

v1->v2:
introduce the ARCH_HAS_GIGANTIC_PAGE as Michal Hocko [off-list ref] suggested

Arm64 supports different size of gigantic page which can be seen from:
commit 084bd29810a5 ("ARM64: mm: HugeTLB support.")
commit 66b3923a1a0f ("arm64: hugetlb: add support for PTE contiguous bit")

So I tried to use this function by adding hugepagesz=1G in kernel
parameters, with CONFIG_CMA=y. However, when I
echo xx > \
  /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
it failed with the following info:
-bash: echo: write error: Invalid argument

This is a v4 patchset which make gigantic page can be
allocated and freed at runtime for arch arm64,
with CONFIG_CMA=y or other related configs is enabled.

You can see the former discussions at:
https://lkml.org/lkml/2016/8/18/310
https://lkml.org/lkml/2016/8/21/410
https://lkml.org/lkml/2016/8/22/319

Yisheng Xie (2):
  mm/hugetlb: Introduce ARCH_HAS_GIGANTIC_PAGE
  arm64 Kconfig: Select gigantic page

 arch/arm64/Kconfig | 1 +
 arch/s390/Kconfig  | 1 +
 arch/x86/Kconfig   | 1 +
 fs/Kconfig         | 3 +++
 mm/hugetlb.c       | 2 +-
 5 files changed, 7 insertions(+), 1 deletion(-)

-- 
1.7.12.4

Arm64 supports gigantic page after
commit 084bd29810a5 ("ARM64: mm: HugeTLB support.")
however, it can only be allocated at boottime and can't be freed.

This patch selects ARCH_HAS_GIGANTIC_PAGE to make gigantic pages
can be allocated and freed at runtime for arch arm64.

Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Yisheng Xie <redacted>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index bc3f00f..92217f6 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -9,6 +9,7 @@ config ARM64
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_GCOV_PROFILE_ALL
+	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

-- 
1.7.12.4

Avoid making ifdef get pretty unwieldy if many ARCHs support gigantic page.
No functional change with this patch.

Signed-off-by: Yisheng Xie <redacted>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Naoya Horiguchi <redacted>
---
 arch/s390/Kconfig | 1 +
 arch/x86/Kconfig  | 1 +
 fs/Kconfig        | 3 +++
 mm/hugetlb.c      | 2 +-
 4 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c109f07..74a9e45 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig

@@ -71,6 +71,7 @@ config S390
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_GCOV_PROFILE_ALL
+	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2a1f0ce..aa0b26a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -28,6 +28,7 @@ config X86
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_GCOV_PROFILE_ALL
+	select ARCH_HAS_GIGANTIC_PAGE		if X86_64
 	select ARCH_HAS_KCOV			if X86_64
 	select ARCH_HAS_PMEM_API		if X86_64
 	select ARCH_HAS_MMIO_FLUSH

diff --git a/fs/Kconfig b/fs/Kconfig
index 2bc7ad7..b938205 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig

@@ -199,6 +199,9 @@ config HUGETLBFS
 config HUGETLB_PAGE
 	def_bool HUGETLBFS
 
+config ARCH_HAS_GIGANTIC_PAGE
+	bool
+
 source "fs/configfs/Kconfig"
 source "fs/efivarfs/Kconfig"
 

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 87e11d8..8488dcc 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c

@@ -1022,7 +1022,7 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
 		((node = hstate_next_node_to_free(hs, mask)) || 1);	\
 		nr_nodes--)
 
-#if (defined(CONFIG_X86_64) || defined(CONFIG_S390)) && \
+#if defined(CONFIG_ARCH_HAS_GIGANTIC_PAGE) && \
 	((defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || \
 	defined(CONFIG_CMA))
 static void destroy_compound_gigantic_page(struct page *page,

-- 
1.7.12.4

On Friday, September 30, 2016 5:26 PM Yisheng Xie

Avoid making ifdef get pretty unwieldy if many ARCHs support gigantic page.
No functional change with this patch.

Signed-off-by: Yisheng Xie <redacted>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Naoya Horiguchi <redacted>
---

Acked-by: Hillf Danton <redacted>

On Friday, September 30, 2016 5:26 PM Yisheng Xie wrote

Arm64 supports gigantic page after
commit 084bd29810a5 ("ARM64: mm: HugeTLB support.")
however, it can only be allocated at boottime and can't be freed.

This patch selects ARCH_HAS_GIGANTIC_PAGE to make gigantic pages
can be allocated and freed at runtime for arch arm64.

Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Yisheng Xie <redacted>
---

Acked-by: Hillf Danton <redacted>