[PATCH v5 0/4] Fix free/allocation of runtime gigantic pages

[PATCH v5 0/4] Fix free/allocation of runtime gigantic pages

[Alexandre Ghiti]

This series fixes sh and sparc that did not advertise their gigantic page
support and then were not able to allocate and free those pages at runtime.
It renames MEMORY_ISOLATION && COMPACTION || CMA condition into the more
accurate CONTIG_ALLOC, since it allows the definition of alloc_contig_range
function.
Finally, it then fixes the wrong definition of ARCH_HAS_GIGANTIC_PAGE config
that, without MEMORY_ISOLATION && COMPACTION || CMA defined, did not allow
architectures to free boottime allocated gigantic pages although unrelated.

Changes in v5:
- Fix bug in previous version thanks to Mike Kravetz
- Fix block comments that did not respect coding style thanks to Dave Hensen
- Define ARCH_HAS_GIGANTIC_PAGE only for sparc64 as advised by David Miller
- Factorize "def_bool" and "depends on" thanks to Vlastimil Babka

Changes in v4 as suggested by Dave Hensen:
- Split previous version into small patches
- Do not compile alloc_gigantic** functions for architectures that do not
  support those pages
- Define correct ARCH_HAS_GIGANTIC_PAGE in all arch that support them to avoid
  useless runtime check
- Add comment in set_max_huge_pages to explain that freeing is possible even
  without CONTIG_ALLOC defined
- Remove gigantic_page_supported function across all archs

Changes in v3 as suggested by Vlastimil Babka and Dave Hansen:
- config definition was wrong and is now in mm/Kconfig
- COMPACTION_CORE was renamed in CONTIG_ALLOC

Changes in v2 as suggested by Vlastimil Babka:
- Get rid of ARCH_HAS_GIGANTIC_PAGE
- Get rid of architecture specific gigantic_page_supported
- Factorize CMA or (MEMORY_ISOLATION && COMPACTION) into COMPACTION_CORE

*** BLURB HERE ***

Alexandre Ghiti (4):
  sh: Advertise gigantic page support
  sparc: Advertise gigantic page support
  mm: Simplify MEMORY_ISOLATION && COMPACTION || CMA into CONTIG_ALLOC
  hugetlb: allow to free gigantic pages regardless of the configuration

 arch/arm64/Kconfig                           |  2 +-
 arch/arm64/include/asm/hugetlb.h             |  4 --
 arch/powerpc/include/asm/book3s/64/hugetlb.h |  7 ---
 arch/powerpc/platforms/Kconfig.cputype       |  2 +-
 arch/s390/Kconfig                            |  2 +-
 arch/s390/include/asm/hugetlb.h              |  3 --
 arch/sh/Kconfig                              |  1 +
 arch/sparc/Kconfig                           |  1 +
 arch/x86/Kconfig                             |  2 +-
 arch/x86/include/asm/hugetlb.h               |  4 --
 arch/x86/mm/hugetlbpage.c                    |  2 +-
 include/linux/gfp.h                          |  4 +-
 mm/Kconfig                                   |  3 ++
 mm/hugetlb.c                                 | 54 ++++++++++++--------
 mm/page_alloc.c                              |  7 ++-
 15 files changed, 48 insertions(+), 50 deletions(-)

-- 
2.20.1

[PATCH v5 1/4] sh: Advertise gigantic page support

[Alexandre Ghiti]

sh actually supports gigantic pages and selecting
ARCH_HAS_GIGANTIC_PAGE allows it to allocate and free
gigantic pages at runtime.

At least sdk7786_defconfig exposes such a configuration with
huge pages of 64MB, pages of 4KB and MAX_ORDER = 11:
HPAGE_SHIFT (26) - PAGE_SHIFT (12) = 14 >= MAX_ORDER (11)

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/sh/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index a9c36f95744a..299a17bed67c 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -53,6 +53,7 @@ config SUPERH
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_NMI
 	select NEED_SG_DMA_LENGTH
+	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
 
 	help
 	  The SuperH is a RISC processor targeted for use in embedded systems
-- 
2.20.1

[PATCH v5 2/4] sparc: Advertise gigantic page support

[Alexandre Ghiti]

sparc actually supports gigantic pages and selecting
ARCH_HAS_GIGANTIC_PAGE allows it to allocate and free
gigantic pages at runtime.

sparc allows configuration such as huge pages of 16GB,
pages of 8KB and MAX_ORDER = 13 (default):
HPAGE_SHIFT (34) - PAGE_SHIFT (13) = 21 >= MAX_ORDER (13)

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/sparc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index d5dd652fb8cc..0b7f0e0fefa5 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -90,6 +90,7 @@ config SPARC64
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_PTE_SPECIAL
 	select PCI_DOMAINS if PCI
+	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
 
 config ARCH_DEFCONFIG
 	string
-- 
2.20.1

[PATCH v5 3/4] mm: Simplify MEMORY_ISOLATION && COMPACTION || CMA into CONTIG_ALLOC

[Alexandre Ghiti]

This condition allows to define alloc_contig_range, so simplify
it into a more accurate naming.

Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/arm64/Kconfig                     | 2 +-
 arch/powerpc/platforms/Kconfig.cputype | 2 +-
 arch/s390/Kconfig                      | 2 +-
 arch/sh/Kconfig                        | 2 +-
 arch/sparc/Kconfig                     | 2 +-
 arch/x86/Kconfig                       | 2 +-
 arch/x86/mm/hugetlbpage.c              | 2 +-
 include/linux/gfp.h                    | 2 +-
 mm/Kconfig                             | 3 +++
 mm/page_alloc.c                        | 3 +--
 10 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a4168d366127..091a513b93e9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -18,7 +18,7 @@ config ARM64
 	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
 	select ARCH_HAS_PTE_SPECIAL
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 8c7464c3f27f..f677c8974212 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -319,7 +319,7 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 config PPC_RADIX_MMU
 	bool "Radix MMU Support"
 	depends on PPC_BOOK3S_64
-	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
 	default y
 	help
 	  Enable support for the Power ISA 3.0 Radix style MMU. Currently this
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index ed554b09eb3f..1c57b83c76f5 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -69,7 +69,7 @@ config S390
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SET_MEMORY
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 299a17bed67c..c7266302691c 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -53,7 +53,7 @@ config SUPERH
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_NMI
 	select NEED_SG_DMA_LENGTH
-	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
 
 	help
 	  The SuperH is a RISC processor targeted for use in embedded systems
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 0b7f0e0fefa5..ca33c80870e2 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -90,7 +90,7 @@ config SPARC64
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_PTE_SPECIAL
 	select PCI_DOMAINS if PCI
-	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
 
 config ARCH_DEFCONFIG
 	string
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 68261430fe6e..8ba90f3e0038 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,7 +23,7 @@ config X86_64
 	def_bool y
 	depends on 64BIT
 	# Options that are inherently 64-bit kernel only:
-	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
 	select ARCH_SUPPORTS_INT128
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select HAVE_ARCH_SOFT_DIRTY
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 92e4c4b85bba..fab095362c50 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -203,7 +203,7 @@ static __init int setup_hugepagesz(char *opt)
 }
 __setup("hugepagesz=", setup_hugepagesz);
 
-#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
+#ifdef CONFIG_CONTIG_ALLOC
 static __init int gigantic_pages_init(void)
 {
 	/* With compaction or CMA we can allocate gigantic pages at runtime */
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 5f5e25fd6149..1f1ad9aeebb9 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -585,7 +585,7 @@ static inline bool pm_suspended_storage(void)
 }
 #endif /* CONFIG_PM_SLEEP */
 
-#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
+#ifdef CONFIG_CONTIG_ALLOC
 /* The below functions must be run on a range from a single zone. */
 extern int alloc_contig_range(unsigned long start, unsigned long end,
 			      unsigned migratetype, gfp_t gfp_mask);
diff --git a/mm/Kconfig b/mm/Kconfig
index 25c71eb8a7db..137eadc18732 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -258,6 +258,9 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
 config ARCH_ENABLE_THP_MIGRATION
 	bool
 
+config CONTIG_ALLOC
+       def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
+
 config PHYS_ADDR_T_64BIT
 	def_bool 64BIT
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 35fdde041f5c..ac9c45ffb344 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8024,8 +8024,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 	return true;
 }
 
-#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
-
+#ifdef CONFIG_CONTIG_ALLOC
 static unsigned long pfn_max_align_down(unsigned long pfn)
 {
 	return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES,
-- 
2.20.1

[PATCH v5 4/4] hugetlb: allow to free gigantic pages regardless of the configuration

[Alexandre Ghiti]

On systems without CONTIG_ALLOC activated but that support gigantic pages,
boottime reserved gigantic pages can not be freed at all. This patch
simply enables the possibility to hand back those pages to memory
allocator.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/arm64/Kconfig                           |  2 +-
 arch/arm64/include/asm/hugetlb.h             |  4 --
 arch/powerpc/include/asm/book3s/64/hugetlb.h |  7 ---
 arch/powerpc/platforms/Kconfig.cputype       |  2 +-
 arch/s390/Kconfig                            |  2 +-
 arch/s390/include/asm/hugetlb.h              |  3 --
 arch/sh/Kconfig                              |  2 +-
 arch/sparc/Kconfig                           |  2 +-
 arch/x86/Kconfig                             |  2 +-
 arch/x86/include/asm/hugetlb.h               |  4 --
 include/linux/gfp.h                          |  2 +-
 mm/hugetlb.c                                 | 54 ++++++++++++--------
 mm/page_alloc.c                              |  4 +-
 13 files changed, 42 insertions(+), 48 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 091a513b93e9..af687eff884a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -18,7 +18,7 @@ config ARM64
 	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
 	select ARCH_HAS_PTE_SPECIAL
diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index fb6609875455..59893e766824 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -65,8 +65,4 @@ extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
 
 #include <asm-generic/hugetlb.h>
 
-#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
-static inline bool gigantic_page_supported(void) { return true; }
-#endif
-
 #endif /* __ASM_HUGETLB_H */
diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h
index 5b0177733994..d04a0bcc2f1c 100644
--- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
+++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
@@ -32,13 +32,6 @@ static inline int hstate_get_psize(struct hstate *hstate)
 	}
 }
 
-#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
-static inline bool gigantic_page_supported(void)
-{
-	return true;
-}
-#endif
-
 /* hugepd entry valid bit */
 #define HUGEPD_VAL_BITS		(0x8000000000000000UL)
 
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index f677c8974212..dc0328de20cd 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -319,7 +319,7 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 config PPC_RADIX_MMU
 	bool "Radix MMU Support"
 	depends on PPC_BOOK3S_64
-	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+	select ARCH_HAS_GIGANTIC_PAGE
 	default y
 	help
 	  Enable support for the Power ISA 3.0 Radix style MMU. Currently this
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 1c57b83c76f5..d84e536796b1 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -69,7 +69,7 @@ config S390
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SET_MEMORY
diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index 2d1afa58a4b6..bd191560efcf 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -116,7 +116,4 @@ static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
 	return pte_modify(pte, newprot);
 }
 
-#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
-static inline bool gigantic_page_supported(void) { return true; }
-#endif
 #endif /* _ASM_S390_HUGETLB_H */
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index c7266302691c..404b12a0d871 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -53,7 +53,7 @@ config SUPERH
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_NMI
 	select NEED_SG_DMA_LENGTH
-	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+	select ARCH_HAS_GIGANTIC_PAGE
 
 	help
 	  The SuperH is a RISC processor targeted for use in embedded systems
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index ca33c80870e2..234a6bd46e89 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -90,7 +90,7 @@ config SPARC64
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_PTE_SPECIAL
 	select PCI_DOMAINS if PCI
-	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+	select ARCH_HAS_GIGANTIC_PAGE
 
 config ARCH_DEFCONFIG
 	string
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8ba90f3e0038..ff24eaeef211 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,7 +23,7 @@ config X86_64
 	def_bool y
 	depends on 64BIT
 	# Options that are inherently 64-bit kernel only:
-	select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_SUPPORTS_INT128
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select HAVE_ARCH_SOFT_DIRTY
diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h
index 7469d321f072..f65cfb48cfdd 100644
--- a/arch/x86/include/asm/hugetlb.h
+++ b/arch/x86/include/asm/hugetlb.h
@@ -17,8 +17,4 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }
 
-#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
-static inline bool gigantic_page_supported(void) { return true; }
-#endif
-
 #endif /* _ASM_X86_HUGETLB_H */
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 1f1ad9aeebb9..58ea44bf75de 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -589,8 +589,8 @@ static inline bool pm_suspended_storage(void)
 /* The below functions must be run on a range from a single zone. */
 extern int alloc_contig_range(unsigned long start, unsigned long end,
 			      unsigned migratetype, gfp_t gfp_mask);
-extern void free_contig_range(unsigned long pfn, unsigned nr_pages);
 #endif
+extern void free_contig_range(unsigned long pfn, unsigned int nr_pages);
 
 #ifdef CONFIG_CMA
 /* CMA stuff */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index afef61656c1e..7c57d58051ec 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1058,6 +1058,7 @@ static void free_gigantic_page(struct page *page, unsigned int order)
 	free_contig_range(page_to_pfn(page), 1 << order);
 }
 
+#ifdef CONFIG_CONTIG_ALLOC
 static int __alloc_gigantic_page(unsigned long start_pfn,
 				unsigned long nr_pages, gfp_t gfp_mask)
 {
@@ -1142,11 +1143,20 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
 
 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
 static void prep_compound_gigantic_page(struct page *page, unsigned int order);
+#else /* !CONFIG_CONTIG_ALLOC */
+static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
+					int nid, nodemask_t *nodemask)
+{
+	return NULL;
+}
+#endif /* CONFIG_CONTIG_ALLOC */
 
 #else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
-static inline bool gigantic_page_supported(void) { return false; }
 static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
-		int nid, nodemask_t *nodemask) { return NULL; }
+					int nid, nodemask_t *nodemask)
+{
+	return NULL;
+}
 static inline void free_gigantic_page(struct page *page, unsigned int order) { }
 static inline void destroy_compound_gigantic_page(struct page *page,
 						unsigned int order) { }
@@ -1156,9 +1166,6 @@ static void update_and_free_page(struct hstate *h, struct page *page)
 {
 	int i;
 
-	if (hstate_is_gigantic(h) && !gigantic_page_supported())
-		return;
-
 	h->nr_huge_pages--;
 	h->nr_huge_pages_node[page_to_nid(page)]--;
 	for (i = 0; i < pages_per_huge_page(h); i++) {
@@ -2276,13 +2283,24 @@ static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
 }
 
 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
-static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
-						nodemask_t *nodes_allowed)
+static int set_max_huge_pages(struct hstate *h, unsigned long count,
+			      nodemask_t *nodes_allowed)
 {
 	unsigned long min_count, ret;
 
-	if (hstate_is_gigantic(h) && !gigantic_page_supported())
-		return h->max_huge_pages;
+	/*
+	 * Gigantic pages allocation depends on the capability for large page
+	 * range allocation. If the system cannot provide alloc_contig_range,
+	 * allow users to free gigantic pages.
+	 */
+	if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
+		spin_lock(&hugetlb_lock);
+		if (count > persistent_huge_pages(h)) {
+			spin_unlock(&hugetlb_lock);
+			return -EINVAL;
+		}
+		goto decrease_pool;
+	}
 
 	/*
 	 * Increase the pool size
@@ -2322,6 +2340,7 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
 			goto out;
 	}
 
+decrease_pool:
 	/*
 	 * Decrease the pool size
 	 * First return free pages to the buddy allocator (being careful
@@ -2350,9 +2369,10 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
 			break;
 	}
 out:
-	ret = persistent_huge_pages(h);
+	h->max_huge_pages = persistent_huge_pages(h);
 	spin_unlock(&hugetlb_lock);
-	return ret;
+
+	return 0;
 }
 
 #define HSTATE_ATTR_RO(_name) \
@@ -2404,11 +2424,6 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
 	int err;
 	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
 
-	if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
-		err = -EINVAL;
-		goto out;
-	}
-
 	if (nid == NUMA_NO_NODE) {
 		/*
 		 * global hstate attribute
@@ -2428,15 +2443,12 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
 	} else
 		nodes_allowed = &node_states[N_MEMORY];
 
-	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
+	err = set_max_huge_pages(h, count, nodes_allowed);
 
 	if (nodes_allowed != &node_states[N_MEMORY])
 		NODEMASK_FREE(nodes_allowed);
 
-	return len;
-out:
-	NODEMASK_FREE(nodes_allowed);
-	return err;
+	return err ? err : len;
 }
 
 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ac9c45ffb344..a4547d90fa7a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8234,8 +8234,9 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 				pfn_max_align_up(end), migratetype);
 	return ret;
 }
+#endif /* CONFIG_CONTIG_ALLOC */
 
-void free_contig_range(unsigned long pfn, unsigned nr_pages)
+void free_contig_range(unsigned long pfn, unsigned int nr_pages)
 {
 	unsigned int count = 0;
 
@@ -8247,7 +8248,6 @@ void free_contig_range(unsigned long pfn, unsigned nr_pages)
 	}
 	WARN(count != 0, "%d pages are still in use!\n", count);
 }
-#endif
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 /*
-- 
2.20.1

Re: [PATCH v5 2/4] sparc: Advertise gigantic page support

[David Miller]

From: Alexandre Ghiti <alex@ghiti.fr>
Date: Wed,  6 Mar 2019 14:00:03 -0500

> sparc actually supports gigantic pages and selecting
> ARCH_HAS_GIGANTIC_PAGE allows it to allocate and free
> gigantic pages at runtime.
> 
> sparc allows configuration such as huge pages of 16GB,
> pages of 8KB and MAX_ORDER = 13 (default):
> HPAGE_SHIFT (34) - PAGE_SHIFT (13) = 21 >= MAX_ORDER (13)
> 
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

Much better.

Acked-by: David S. Miller <davem@davemloft.net>

Re: [PATCH v5 2/4] sparc: Advertise gigantic page support

[Alex Ghiti]

On 3/6/19 2:04 PM, David Miller wrote:
> From: Alexandre Ghiti <alex@ghiti.fr>
> Date: Wed,  6 Mar 2019 14:00:03 -0500
>
>> sparc actually supports gigantic pages and selecting
>> ARCH_HAS_GIGANTIC_PAGE allows it to allocate and free
>> gigantic pages at runtime.
>>
>> sparc allows configuration such as huge pages of 16GB,
>> pages of 8KB and MAX_ORDER = 13 (default):
>> HPAGE_SHIFT (34) - PAGE_SHIFT (13) = 21 >= MAX_ORDER (13)
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Much better.
>
> Acked-by: David S. Miller <davem@davemloft.net>
Thanks !

Alex

Re: [PATCH v5 4/4] hugetlb: allow to free gigantic pages regardless of the configuration

[Dave Hansen]

On 3/6/19 11:00 AM, Alexandre Ghiti wrote:
> +static int set_max_huge_pages(struct hstate *h, unsigned long count,
> +			      nodemask_t *nodes_allowed)
>  {
>  	unsigned long min_count, ret;
>  
> -	if (hstate_is_gigantic(h) && !gigantic_page_supported())
> -		return h->max_huge_pages;
> +	/*
> +	 * Gigantic pages allocation depends on the capability for large page
> +	 * range allocation. If the system cannot provide alloc_contig_range,
> +	 * allow users to free gigantic pages.
> +	 */
> +	if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
> +		spin_lock(&hugetlb_lock);
> +		if (count > persistent_huge_pages(h)) {
> +			spin_unlock(&hugetlb_lock);
> +			return -EINVAL;
> +		}
> +		goto decrease_pool;
> +	}

We talked about it during the last round and I don't seen any mention of
it here in comments or the changelog: Why is this a goto?  Why don't we
just let the code fall through to the "decrease_pool" label?  Why is
this new block needed at all?  Can't we just remove the old check and
let it be?

Re: [PATCH v5 4/4] hugetlb: allow to free gigantic pages regardless of the configuration

[David Miller]

From: Alexandre Ghiti <alex@ghiti.fr>
Date: Wed,  6 Mar 2019 14:00:05 -0500

> On systems without CONTIG_ALLOC activated but that support gigantic pages,
> boottime reserved gigantic pages can not be freed at all. This patch
> simply enables the possibility to hand back those pages to memory
> allocator.
> 
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

For sparc:

Acked-by: David S. Miller <davem@davemloft.net>

Re: [PATCH v5 3/4] mm: Simplify MEMORY_ISOLATION && COMPACTION || CMA into CONTIG_ALLOC

[Vlastimil Babka]

On 3/6/19 8:00 PM, Alexandre Ghiti wrote:
> This condition allows to define alloc_contig_range, so simplify
> it into a more accurate naming.
> 
> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

(you could have sent this with my ack from v4 as there wasn't
significant change, just the one I suggested :)

Re: [PATCH v5 3/4] mm: Simplify MEMORY_ISOLATION && COMPACTION || CMA into CONTIG_ALLOC

[Alex Ghiti]

On 3/6/19 2:30 PM, Vlastimil Babka wrote:
> On 3/6/19 8:00 PM, Alexandre Ghiti wrote:
>> This condition allows to define alloc_contig_range, so simplify
>> it into a more accurate naming.
>>
>> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>
> (you could have sent this with my ack from v4 as there wasn't
> significant change, just the one I suggested :)

Thanks, that's good to know.

Alex

Re: [PATCH v5 4/4] hugetlb: allow to free gigantic pages regardless of the configuration

[Alex Ghiti]

On 3/6/19 2:16 PM, Dave Hansen wrote:
> On 3/6/19 11:00 AM, Alexandre Ghiti wrote:
>> +static int set_max_huge_pages(struct hstate *h, unsigned long count,
>> +			      nodemask_t *nodes_allowed)
>>   {
>>   	unsigned long min_count, ret;
>>   
>> -	if (hstate_is_gigantic(h) && !gigantic_page_supported())
>> -		return h->max_huge_pages;
>> +	/*
>> +	 * Gigantic pages allocation depends on the capability for large page
>> +	 * range allocation. If the system cannot provide alloc_contig_range,
>> +	 * allow users to free gigantic pages.
>> +	 */
>> +	if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
>> +		spin_lock(&hugetlb_lock);
>> +		if (count > persistent_huge_pages(h)) {
>> +			spin_unlock(&hugetlb_lock);
>> +			return -EINVAL;
>> +		}
>> +		goto decrease_pool;
>> +	}
> We talked about it during the last round and I don't seen any mention of
> it here in comments or the changelog: Why is this a goto?  Why don't we
> just let the code fall through to the "decrease_pool" label?  Why is
> this new block needed at all?  Can't we just remove the old check and
> let it be?

I'll get rid of the goto, I don't know how to justify it properly in a 
comment,
maybe because it is not necessary.
This is not a new block, this means exactly the same as before (remember
gigantic_page_supported() actually meant CONTIG_ALLOC before this series),
except that now we allow a user to free boottime allocated gigantic pages.
And no we cannot just remove the check and let it be since it would modify
the current behaviour, which is to return an error when trying to allocate
gigantic pages whereas alloc_contig_range is not defined. I thought it was
clearly commented above, I can try to make it more explicit.

Re: [PATCH v5 4/4] hugetlb: allow to free gigantic pages regardless of the configuration

[Dave Hansen]

On 3/6/19 12:08 PM, Alex Ghiti wrote:
>>>
>>> +    /*
>>> +     * Gigantic pages allocation depends on the capability for large
>>> page
>>> +     * range allocation. If the system cannot provide
>>> alloc_contig_range,
>>> +     * allow users to free gigantic pages.
>>> +     */
>>> +    if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
>>> +        spin_lock(&hugetlb_lock);
>>> +        if (count > persistent_huge_pages(h)) {
>>> +            spin_unlock(&hugetlb_lock);
>>> +            return -EINVAL;
>>> +        }
>>> +        goto decrease_pool;
>>> +    }
>> We talked about it during the last round and I don't seen any mention of
>> it here in comments or the changelog: Why is this a goto?  Why don't we
>> just let the code fall through to the "decrease_pool" label?  Why is
>> this new block needed at all?  Can't we just remove the old check and
>> let it be?
> 
> I'll get rid of the goto, I don't know how to justify it properly in a
> comment,
> maybe because it is not necessary.
> This is not a new block, this means exactly the same as before (remember
> gigantic_page_supported() actually meant CONTIG_ALLOC before this series),
> except that now we allow a user to free boottime allocated gigantic pages.
> And no we cannot just remove the check and let it be since it would modify
> the current behaviour, which is to return an error when trying to allocate
> gigantic pages whereas alloc_contig_range is not defined. I thought it was
> clearly commented above, I can try to make it more explicit.

OK, that makes sense.  Could you get some of this in the changelog,
please?  Otherwise this all looks good to me.