[PATCH v3 3/4] arch, mm: restore dependency of __kernel_map_pages() of... | linux-arm-kernel

[PATCH v3 3/4] arch, mm: restore dependency of __kernel_map_pages() of DEBUG_PAGEALLOC

From: Mike Rapoport <rppt@kernel.org>
Date: 2020-11-01 17:09:01
Also in: linux-mm, linux-pm, linux-riscv, linux-s390, linuxppc-dev, lkml, sparclinux
Subsystem: arm64 port (aarch64 architecture), linux for powerpc (32-bit and 64-bit), memory management - core, risc-v architecture, s390 architecture, sparc + ultrasparc (sparc/sparc64), the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers: Catalin Marinas, Will Deacon, Madhavan Srinivasan, Michael Ellerman, Andrew Morton, David Hildenbrand, Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, "David S. Miller", Andreas Larsson, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra

From: Mike Rapoport <redacted>

The design of DEBUG_PAGEALLOC presumes that __kernel_map_pages() must never
fail. With this assumption is wouldn't be safe to allow general usage of
this function.

Moreover, some architectures that implement __kernel_map_pages() have this
function guarded by #ifdef DEBUG_PAGEALLOC and some refuse to map/unmap
pages when page allocation debugging is disabled at runtime.

As all the users of __kernel_map_pages() were converted to use
debug_pagealloc_map_pages() it is safe to make it available only when
DEBUG_PAGEALLOC is set.

Signed-off-by: Mike Rapoport <redacted>
---
 arch/Kconfig                     |  3 +++
 arch/arm64/Kconfig               |  4 +---
 arch/arm64/mm/pageattr.c         |  8 ++++++--
 arch/powerpc/Kconfig             |  5 +----
 arch/riscv/Kconfig               |  4 +---
 arch/riscv/include/asm/pgtable.h |  2 --
 arch/riscv/mm/pageattr.c         |  2 ++
 arch/s390/Kconfig                |  4 +---
 arch/sparc/Kconfig               |  4 +---
 arch/x86/Kconfig                 |  4 +---
 arch/x86/mm/pat/set_memory.c     |  2 ++
 include/linux/mm.h               | 10 +++++++---
 12 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 56b6ccc0e32d..56d4752b6db6 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig

@@ -1028,6 +1028,9 @@ config HAVE_STATIC_CALL_INLINE
 	bool
 	depends on HAVE_STATIC_CALL
 
+config ARCH_SUPPORTS_DEBUG_PAGEALLOC
+	bool
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f858c352f72a..5a01dfb77b93 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -71,6 +71,7 @@ config ARM64
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USE_QUEUED_SPINLOCKS
 	select ARCH_USE_SYM_ANNOTATIONS
+	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	select ARCH_SUPPORTS_MEMORY_FAILURE
 	select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK
 	select ARCH_SUPPORTS_ATOMIC_RMW

@@ -1005,9 +1006,6 @@ config HOLES_IN_ZONE
 
 source "kernel/Kconfig.hz"
 
-config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	def_bool y
-
 config ARCH_SPARSEMEM_ENABLE
 	def_bool y
 	select SPARSEMEM_VMEMMAP_ENABLE

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 1b94f5b82654..439325532be1 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c

@@ -155,7 +155,7 @@ int set_direct_map_invalid_noflush(struct page *page)
 		.clear_mask = __pgprot(PTE_VALID),
 	};
 
-	if (!rodata_full)
+	if (!debug_pagealloc_enabled() && !rodata_full)
 		return 0;
 
 	return apply_to_page_range(&init_mm,

@@ -170,7 +170,7 @@ int set_direct_map_default_noflush(struct page *page)
 		.clear_mask = __pgprot(PTE_RDONLY),
 	};
 
-	if (!rodata_full)
+	if (!debug_pagealloc_enabled() && !rodata_full)
 		return 0;
 
 	return apply_to_page_range(&init_mm,

@@ -178,6 +178,7 @@ int set_direct_map_default_noflush(struct page *page)
 				   PAGE_SIZE, change_page_range, &data);
 }
 
+#ifdef CONFIG_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	if (!debug_pagealloc_enabled() && !rodata_full)

@@ -186,6 +187,7 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 	set_memory_valid((unsigned long)page_address(page), numpages, enable);
 }
 
+#ifdef CONFIG_HIBERNATION
 /*
  * This function is used to determine if a linear map page has been marked as
  * not-valid. Walk the page table and check the PTE_VALID bit. This is based

@@ -232,3 +234,5 @@ bool kernel_page_present(struct page *page)
 	ptep = pte_offset_kernel(pmdp, addr);
 	return pte_valid(READ_ONCE(*ptep));
 }
+#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_DEBUG_PAGEALLOC */

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e9f13fe08492..ad8a83f3ddca 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -146,6 +146,7 @@ config PPC
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select ARCH_OPTIONAL_KERNEL_RWX		if ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_SUPPORTS_ATOMIC_RMW
+	select ARCH_SUPPORTS_DEBUG_PAGEALLOC	if PPC32 || PPC_BOOK3S_64
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF		if PPC64
 	select ARCH_USE_QUEUED_RWLOCKS		if PPC_QUEUED_SPINLOCKS

@@ -355,10 +356,6 @@ config PPC_OF_PLATFORM_PCI
 	depends on PCI
 	depends on PPC64 # not supported on 32 bits yet
 
-config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	depends on PPC32 || PPC_BOOK3S_64
-	def_bool y
-
 config ARCH_SUPPORTS_UPROBES
 	def_bool y

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 44377fd7860e..9283c6f9ae2a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig

@@ -14,6 +14,7 @@ config RISCV
 	def_bool y
 	select ARCH_CLOCKSOURCE_INIT
 	select ARCH_SUPPORTS_ATOMIC_RMW
+	select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU

@@ -153,9 +154,6 @@ config ARCH_SELECT_MEMORY_MODEL
 config ARCH_WANT_GENERAL_HUGETLB
 	def_bool y
 
-config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	def_bool y
-
 config SYS_SUPPORTS_HUGETLBFS
 	depends on MMU
 	def_bool y

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 183f1f4b2ae6..41a72861987c 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h

@@ -461,8 +461,6 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 #define VMALLOC_START		0
 #define VMALLOC_END		TASK_SIZE
 
-static inline void __kernel_map_pages(struct page *page, int numpages, int enable) {}
-
 #endif /* !CONFIG_MMU */
 
 #define kern_addr_valid(addr)   (1) /* FIXME */

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 19fecb362d81..321b09d2e2ea 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c

@@ -184,6 +184,7 @@ int set_direct_map_default_noflush(struct page *page)
 	return ret;
 }
 
+#ifdef CONFIG_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	if (!debug_pagealloc_enabled())

@@ -196,3 +197,4 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 		__set_memory((unsigned long)page_address(page), numpages,
 			     __pgprot(0), __pgprot(_PAGE_PRESENT));
 }
+#endif

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 4a2a12be04c9..991a850a6c0b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig

@@ -35,9 +35,6 @@ config GENERIC_LOCKBREAK
 config PGSTE
 	def_bool y if KVM
 
-config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	def_bool y
-
 config AUDIT_ARCH
 	def_bool y

@@ -106,6 +103,7 @@ config S390
 	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
 	select ARCH_STACKWALK
 	select ARCH_SUPPORTS_ATOMIC_RMW
+	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	select ARCH_SUPPORTS_NUMA_BALANCING
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index a6ca135442f9..2c729b8d097a 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig

@@ -88,6 +88,7 @@ config SPARC64
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_ARCH_AUDITSYSCALL
 	select ARCH_SUPPORTS_ATOMIC_RMW
+	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	select HAVE_NMI
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select ARCH_USE_QUEUED_RWLOCKS

@@ -148,9 +149,6 @@ config GENERIC_ISA_DMA
 	bool
 	default y if SPARC32
 
-config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	def_bool y if SPARC64
-
 config PGTABLE_LEVELS
 	default 4 if 64BIT
 	default 3

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f6946b81f74a..0db3fb1da70c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -91,6 +91,7 @@ config X86
 	select ARCH_STACKWALK
 	select ARCH_SUPPORTS_ACPI
 	select ARCH_SUPPORTS_ATOMIC_RMW
+	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_QUEUED_RWLOCKS

@@ -329,9 +330,6 @@ config ZONE_DMA32
 config AUDIT_ARCH
 	def_bool y if X86_64
 
-config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	def_bool y
-
 config KASAN_SHADOW_OFFSET
 	hex
 	depends on KASAN

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 40baa90e74f4..bc9be96b777f 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c

@@ -2194,6 +2194,7 @@ int set_direct_map_default_noflush(struct page *page)
 	return __set_pages_p(page, 1);
 }
 
+#ifdef CONFIG_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	if (PageHighMem(page))

@@ -2239,6 +2240,7 @@ bool kernel_page_present(struct page *page)
 	return (pte_val(*pte) & _PAGE_PRESENT);
 }
 #endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_DEBUG_PAGEALLOC */
 
 int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
 				   unsigned numpages, unsigned long page_flags)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 14e397f3752c..ab0ef6bd351d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h

@@ -2924,7 +2924,11 @@ static inline bool debug_pagealloc_enabled_static(void)
 	return static_branch_unlikely(&_debug_pagealloc_enabled);
 }
 
-#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP)
+#ifdef CONFIG_DEBUG_PAGEALLOC
+/*
+ * To support DEBUG_PAGEALLOC architecture must ensure that
+ * __kernel_map_pages() never fails
+ */
 extern void __kernel_map_pages(struct page *page, int numpages, int enable);
 
 static inline void debug_pagealloc_map_pages(struct page *page,

@@ -2937,13 +2941,13 @@ static inline void debug_pagealloc_map_pages(struct page *page,
 #ifdef CONFIG_HIBERNATION
 extern bool kernel_page_present(struct page *page);
 #endif	/* CONFIG_HIBERNATION */
-#else	/* CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */
+#else	/* CONFIG_DEBUG_PAGEALLOC */
 static inline void debug_pagealloc_map_pages(struct page *page,
 					     int numpages, int enable) {}
 #ifdef CONFIG_HIBERNATION
 static inline bool kernel_page_present(struct page *page) { return true; }
 #endif	/* CONFIG_HIBERNATION */
-#endif	/* CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */
+#endif	/* CONFIG_DEBUG_PAGEALLOC */
 
 #ifdef __HAVE_ARCH_GATE_AREA
 extern struct vm_area_struct *get_gate_vma(struct mm_struct *mm);

-- 
2.28.0


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