hugetlb: allow to free gigantic pages regardless of the configuration

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.

Link: http://lkml.kernel.org/r/20190327063626.18421-5-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: David S. Miller <davem@davemloft.net> [sparc]
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

14 files changed, 61 insertions, 39 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7f7fbd8bd9d5..7a1aa53d188d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -19,7 +19,7 @@ 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_KEEPINITRD
         select ARCH_HAS_MEMBARRIER_SYNC_CORE
diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index c6a07a3b433e..4aad6382f631 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -70,8 +70,4 @@ 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 56140d19c85f..12e150e615b7 100644
--- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
+++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
@@ -36,8 +36,8 @@ static inline int hstate_get_psize(struct hstate *hstate)
         }
 }
 
-#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
-static inline bool gigantic_page_supported(void)
+#define __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED
+static inline bool gigantic_page_runtime_supported(void)
 {
         /*
          * We used gigantic page reservation with hypervisor assist in some case.
@@ -49,7 +49,6 @@ 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 3a31d4289ea4..2794235e9d3e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -331,7 +331,7 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 config PPC_RADIX_MMU
         bool "Radix MMU Support"
         depends on PPC_BOOK3S_64 && HUGETLB_PAGE
-        select ARCH_HAS_GIGANTIC_PAGE if CONTIG_ALLOC
+        select ARCH_HAS_GIGANTIC_PAGE
         select PPC_HAVE_KUEP
         select PPC_HAVE_KUAP
         default y
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 724dbc6b7d33..d0c046af65fa 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -63,7 +63,7 @@ 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..bb59dd964590 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -116,7 +116,9 @@ 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
+static inline bool gigantic_page_runtime_supported(void)
+{
+        return true;
+}
+
 #endif /* _ASM_S390_HUGETLB_H */
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 2a5ec643fec0..2a77033e1e7c 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 566de738e487..7c93f3121ee6 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -92,7 +92,7 @@ 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 526d95abfe5e..f21bc56e5d7b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -22,7 +22,7 @@ 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/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 71d7b77eea50..822f433ac95c 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -126,4 +126,11 @@ static inline pte_t huge_ptep_get(pte_t *ptep)
 }
 #endif
 
+#ifndef __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED
+static inline bool gigantic_page_runtime_supported(void)
+{
+        return IS_ENABLED(CONFIG_ARCH_HAS_GIGANTIC_PAGE);
+}
+#endif /* __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED */
+
 #endif /* _ASM_GENERIC_HUGETLB_H */
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index e77ab30e9328..fb07b503dc45 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
+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 dffe5d9d03ae..2f901a6e13d2 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1059,6 +1059,7 @@ 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)
 {
@@ -1143,11 +1144,20 @@ 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) { }
@@ -1157,7 +1167,7 @@ static void update_and_free_page(struct hstate *h, struct page *page)
 {
         int i;
 
-        if (hstate_is_gigantic(h) && !gigantic_page_supported())
+        if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
                 return;
 
         h->nr_huge_pages--;
@@ -2278,13 +2288,27 @@ found:
 }
 
 #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;
+        spin_lock(&hugetlb_lock);
+
+        /*
+         * Gigantic pages runtime allocation depend on the capability for large
+         * page range allocation.
+         * If the system does not provide this feature, return an error when
+         * the user tries to allocate gigantic pages but let the user free the
+         * boottime allocated gigantic pages.
+         */
+        if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
+                if (count > persistent_huge_pages(h)) {
+                        spin_unlock(&hugetlb_lock);
+                        return -EINVAL;
+                }
+                /* Fall through to decrease pool */
+        }
 
         /*
          * Increase the pool size
@@ -2297,7 +2321,6 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
          * pool might be one hugepage larger than it needs to be, but
          * within all the constraints specified by the sysctls.
          */
-        spin_lock(&hugetlb_lock);
         while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
                 if (!adjust_pool_surplus(h, nodes_allowed, -1))
                         break;
@@ -2352,9 +2375,10 @@ 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) \
@@ -2406,7 +2430,7 @@ 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()) {
+        if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) {
                 err = -EINVAL;
                 goto out;
         }
@@ -2430,15 +2454,13 @@ 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);
 
+out:
         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 2efb6525d932..4ea71bc70413 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8346,8 +8346,9 @@ done:
                                 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;
 
@@ -8359,7 +8360,6 @@ 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
 /*