| Message ID | 20201103162057.22916-4-rppt@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | arch, mm: improve robustness of direct map manipulation | expand |
On 11/3/20 5:20 PM, Mike Rapoport wrote: > From: Mike Rapoport <rppt@linux.ibm.com> Subject should have "on DEBUG_PAGEALLOC" ? > 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 <rppt@linux.ibm.com> > Acked-by: David Hildenbrand <david@redhat.com> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > --- > 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 1d466addb078..a932810cfd90 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 > @@ -1025,9 +1026,6 @@ 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, I don't understand these two hunks. Previous patch calls this for hibernation when CONFIG_ARCH_HAS_SET_DIRECT_MAP, which is true for arm64. Why suddenly this starts to depend on debug_pagealloc_enabled()?
On Wed, Nov 04, 2020 at 07:02:20PM +0100, Vlastimil Babka wrote: > On 11/3/20 5:20 PM, Mike Rapoport wrote: > > From: Mike Rapoport <rppt@linux.ibm.com> > > Subject should have "on DEBUG_PAGEALLOC" ? > > > 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 <rppt@linux.ibm.com> > > Acked-by: David Hildenbrand <david@redhat.com> > > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > --- > > 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 1d466addb078..a932810cfd90 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 > > @@ -1025,9 +1026,6 @@ 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, > > I don't understand these two hunks. Previous patch calls this for > hibernation when CONFIG_ARCH_HAS_SET_DIRECT_MAP, which is true for arm64. > Why suddenly this starts to depend on debug_pagealloc_enabled()? I was confused about this for quite a long :) On arm64 the changes to direct^w linear map are allowed when debug_page_alloc() || rodata_full In hibernation we essentially have now if (1) set_direct_map(something) else debug_page_alloc_map() With debug_pagealloc enabled but with rodata_full disabled arm64 versions of set_direct_map_*() will become a nop, so a page that was unmapped by debug_pagealloc() will not be mapped back. I'm still puzzled how hibernation might ever need to save a free page, but that's another story.
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 1d466addb078..a932810cfd90 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 @@ -1025,9 +1026,6 @@ 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);