On 5/25/21 12:02 PM, Mike Rapoport wrote: > On Tue, May 25, 2021 at 11:30:15AM +0530, Anshuman Khandual wrote: >> >> On 5/24/21 12:22 PM, Mike Rapoport wrote: >>> Hello Anshuman, >>> >>> On Mon, May 24, 2021 at 10:28:32AM +0530, Anshuman Khandual wrote: >>>> >>>> On 4/22/21 1:20 PM, Anshuman Khandual wrote: >>>>> Platforms like arm and arm64 have redefined pfn_valid() because their early >>>>> memory sections might have contained memmap holes after freeing parts of it >>>>> during boot, which should be skipped while validating a pfn for struct page >>>>> backing. This scenario on certain platforms where memmap is not continuous, >>>>> could be captured with a new option CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES. >>>>> Then the generic pfn_valid() can be improved to accommodate such platforms. >>>>> This reduces overall code footprint and also improves maintainability. >>>>> >>>>> free_unused_memmap() and pfn_to_online_page() have been updated to include >>>>> such cases. This also exports memblock_is_memory() for all drivers that use >>>>> pfn_valid() but lack required visibility. After the new config is in place, >>>>> drop CONFIG_HAVE_ARCH_PFN_VALID from arm64 platforms. >>>>> >>>>> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> >>>>> Cc: Will Deacon <will@xxxxxxxxxx> >>>>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >>>>> Cc: Mike Rapoport <rppt@xxxxxxxxxx> >>>>> Cc: David Hildenbrand <david@xxxxxxxxxx> >>>>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >>>>> Cc: linux-kernel@xxxxxxxxxxxxxxx >>>>> Cc: linux-mm@xxxxxxxxx >>>>> Suggested-by: David Hildenbrand <david@xxxxxxxxxx> >>>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> >>>>> --- >>>>> This patch applies on the latest mainline kernel after Mike's series >>>>> regarding arm64 based pfn_valid(). >>>>> >>>>> https://lore.kernel.org/linux-mm/20210422061902.21614-1-rppt@xxxxxxxxxx/T/#t >>>>> >>>>> Changes in RFC V2: >>>>> >>>>> - Dropped support for arm (32 bit) >>>>> - Replaced memblock_is_map_memory() check with memblock_is_memory() >>>>> - MEMBLOCK_NOMAP memory are no longer skipped for pfn_valid() >>>>> - Updated pfn_to_online_page() per David >>>>> - Updated free_unused_memmap() to preserve existing semantics per Mike >>>>> - Exported memblock_is_memory() instead of memblock_is_map_memory() >>>>> >>>>> Changes in RFC V1: >>>>> >>>>> - https://patchwork.kernel.org/project/linux-mm/patch/1615174073-10520-1-git-send-email-anshuman.khandual@xxxxxxx/ >>>>> >>>>> arch/arm64/Kconfig | 2 +- >>>>> arch/arm64/include/asm/page.h | 1 - >>>>> arch/arm64/mm/init.c | 41 ----------------------------------- >>>>> include/linux/mmzone.h | 18 ++++++++++++++- >>>>> mm/Kconfig | 9 ++++++++ >>>>> mm/memblock.c | 8 +++++-- >>>>> mm/memory_hotplug.c | 5 +++++ >>>>> 7 files changed, 38 insertions(+), 46 deletions(-) >>>>> >>>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>>>> index b4a9b493ce72..4cdc3570ffa9 100644 >>>>> --- a/arch/arm64/Kconfig >>>>> +++ b/arch/arm64/Kconfig >>>>> @@ -144,7 +144,6 @@ config ARM64 >>>>> select HAVE_ARCH_KGDB >>>>> select HAVE_ARCH_MMAP_RND_BITS >>>>> select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT >>>>> - select HAVE_ARCH_PFN_VALID >>>>> select HAVE_ARCH_PREL32_RELOCATIONS >>>>> select HAVE_ARCH_SECCOMP_FILTER >>>>> select HAVE_ARCH_STACKLEAK >>>>> @@ -167,6 +166,7 @@ config ARM64 >>>>> if $(cc-option,-fpatchable-function-entry=2) >>>>> select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \ >>>>> if DYNAMIC_FTRACE_WITH_REGS >>>>> + select HAVE_EARLY_SECTION_MEMMAP_HOLES >>>>> select HAVE_EFFICIENT_UNALIGNED_ACCESS >>>>> select HAVE_FAST_GUP >>>>> select HAVE_FTRACE_MCOUNT_RECORD >>>>> diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h >>>>> index 75ddfe671393..fcbef3eec4b2 100644 >>>>> --- a/arch/arm64/include/asm/page.h >>>>> +++ b/arch/arm64/include/asm/page.h >>>>> @@ -37,7 +37,6 @@ void copy_highpage(struct page *to, struct page *from); >>>>> >>>>> typedef struct page *pgtable_t; >>>>> >>>>> -int pfn_valid(unsigned long pfn); >>>>> int pfn_is_map_memory(unsigned long pfn); >>>>> >>>>> #include <asm/memory.h> >>>>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >>>>> index f431b38d0837..5731a11550d8 100644 >>>>> --- a/arch/arm64/mm/init.c >>>>> +++ b/arch/arm64/mm/init.c >>>>> @@ -217,47 +217,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) >>>>> free_area_init(max_zone_pfns); >>>>> } >>>>> >>>>> -int pfn_valid(unsigned long pfn) >>>>> -{ >>>>> - phys_addr_t addr = PFN_PHYS(pfn); >>>>> - >>>>> - /* >>>>> - * Ensure the upper PAGE_SHIFT bits are clear in the >>>>> - * pfn. Else it might lead to false positives when >>>>> - * some of the upper bits are set, but the lower bits >>>>> - * match a valid pfn. >>>>> - */ >>>>> - if (PHYS_PFN(addr) != pfn) >>>>> - return 0; >>>>> - >>>>> -#ifdef CONFIG_SPARSEMEM >>>>> -{ >>>>> - struct mem_section *ms; >>>>> - >>>>> - if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) >>>>> - return 0; >>>>> - >>>>> - ms = __pfn_to_section(pfn); >>>>> - if (!valid_section(ms)) >>>>> - return 0; >>>>> - >>>>> - /* >>>>> - * ZONE_DEVICE memory does not have the memblock entries. >>>>> - * memblock_is_memory() check for ZONE_DEVICE based >>>>> - * addresses will always fail. Even the normal hotplugged >>>>> - * memory will never have MEMBLOCK_NOMAP flag set in their >>>>> - * memblock entries. Skip memblock search for all non early >>>>> - * memory sections covering all of hotplug memory including >>>>> - * both normal and ZONE_DEVICE based. >>>>> - */ >>>>> - if (!early_section(ms)) >>>>> - return pfn_section_valid(ms, pfn); >>>>> -} >>>>> -#endif >>>>> - return memblock_is_memory(addr); >>>>> -} >>>>> -EXPORT_SYMBOL(pfn_valid); >>>>> - >>>>> int pfn_is_map_memory(unsigned long pfn) >>>>> { >>>>> phys_addr_t addr = PFN_PHYS(pfn); >>>>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >>>>> index 961f0eeefb62..18bf71665211 100644 >>>>> --- a/include/linux/mmzone.h >>>>> +++ b/include/linux/mmzone.h >>>>> @@ -1421,10 +1421,22 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) >>>>> * >>>>> * Return: 1 for PFNs that have memory map entries and 0 otherwise >>>>> */ >>>>> +bool memblock_is_memory(phys_addr_t addr); >>>>> + >>>>> static inline int pfn_valid(unsigned long pfn) >>>>> { >>>>> + phys_addr_t addr = PFN_PHYS(pfn); >>>>> struct mem_section *ms; >>>>> >>>>> + /* >>>>> + * Ensure the upper PAGE_SHIFT bits are clear in the >>>>> + * pfn. Else it might lead to false positives when >>>>> + * some of the upper bits are set, but the lower bits >>>>> + * match a valid pfn. >>>>> + */ >>>>> + if (PHYS_PFN(addr) != pfn) >>>>> + return 0; >>>>> + >>>>> if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) >>>>> return 0; >>>>> ms = __nr_to_section(pfn_to_section_nr(pfn)); >>>>> @@ -1434,7 +1446,11 @@ static inline int pfn_valid(unsigned long pfn) >>>>> * Traditionally early sections always returned pfn_valid() for >>>>> * the entire section-sized span. >>>>> */ >>>>> - return early_section(ms) || pfn_section_valid(ms, pfn); >>>>> + if (early_section(ms)) >>>>> + return IS_ENABLED(CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES) ? >>>>> + memblock_is_memory(pfn << PAGE_SHIFT) : 1; >>>>> + >>>>> + return pfn_section_valid(ms, pfn); >>>>> } >>>>> #endif >>>> >>>> Hello David/Mike, >>>> >>>> Now that pfn_is_map_memory() usage has been decoupled from pfn_valid() and >>>> SPARSEMEM_VMEMMAP is only available memory model on arm64, wondering if we >>>> still need this HAVE_EARLY_SECTION_MEMMAP_HOLES proposal ? Please do kindly >>>> suggest. Thank you. >>> >>> Even now arm64 still frees parts of the memory map and pfn_valid() should >>> be able to tell if a part of a section is freed or not. >>> >>> For instance for the following memory configuration >>> >>> |<----section---->|<----hole---->|<----section---->| >>> +--------+--------+--------------+--------+--------+ >>> | bank 0 | unused | | bank 1 | unused | >>> +--------+--------+--------------+--------+--------+ >>> >>> the memory map corresponding to the "unused" areas is freed, but the generic >>> pfn_valid() will still return 1 there. >> >> But is not free_unused_memmap() return early when CONFIG_SPARSEMEM_VMEMMAP >> is enabled, which is the only option now on arm64. Then how can memmap have >> holes (from unused areas) anymore ? Am I missing something here. > > Ah, you are right, I missed this detail myself :) > > With CONFIG_SPARSEMEM_VMEMMAP as the only memory model for arm64, we can > simply rid of arm64::pfn_valid() without any changes to the generic > version. Though just moved the pfn bits sanity check into generic pfn_valid(). I hope this looks okay. >From 7a63f460bcb6ae171c2081bfad81edd9e8f3b7a0 Mon Sep 17 00:00:00 2001 From: Anshuman Khandual <anshuman.khandual@xxxxxxx> Date: Tue, 25 May 2021 10:27:09 +0100 Subject: [PATCH] arm64/mm: Drop HAVE_ARCH_PFN_VALID CONFIG_SPARSEMEM_VMEMMAP is now the only available memory model on arm64 platforms and free_unused_memmap() would just return without creating any holes in the memmap mapping. There is no need for any special handling in pfn_valid() and HAVE_ARCH_PFN_VALID can just be dropped. This also moves the pfn upper bits sanity check into generic pfn_valid(). Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> --- arch/arm64/Kconfig | 1 - arch/arm64/include/asm/page.h | 1 - arch/arm64/mm/init.c | 37 ----------------------------------- include/linux/mmzone.h | 9 +++++++++ 4 files changed, 9 insertions(+), 39 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index d7dc8698cf8e..7904728befcc 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -154,7 +154,6 @@ config ARM64 select HAVE_ARCH_KGDB select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT - select HAVE_ARCH_PFN_VALID select HAVE_ARCH_PREL32_RELOCATIONS select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET select HAVE_ARCH_SECCOMP_FILTER diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index 75ddfe671393..fcbef3eec4b2 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -37,7 +37,6 @@ void copy_highpage(struct page *to, struct page *from); typedef struct page *pgtable_t; -int pfn_valid(unsigned long pfn); int pfn_is_map_memory(unsigned long pfn); #include <asm/memory.h> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 725aa84f2faa..49019ea0c8a8 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -219,43 +219,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) free_area_init(max_zone_pfns); } -int pfn_valid(unsigned long pfn) -{ - phys_addr_t addr = PFN_PHYS(pfn); - struct mem_section *ms; - - /* - * Ensure the upper PAGE_SHIFT bits are clear in the - * pfn. Else it might lead to false positives when - * some of the upper bits are set, but the lower bits - * match a valid pfn. - */ - if (PHYS_PFN(addr) != pfn) - return 0; - - if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) - return 0; - - ms = __pfn_to_section(pfn); - if (!valid_section(ms)) - return 0; - - /* - * ZONE_DEVICE memory does not have the memblock entries. - * memblock_is_map_memory() check for ZONE_DEVICE based - * addresses will always fail. Even the normal hotplugged - * memory will never have MEMBLOCK_NOMAP flag set in their - * memblock entries. Skip memblock search for all non early - * memory sections covering all of hotplug memory including - * both normal and ZONE_DEVICE based. - */ - if (!early_section(ms)) - return pfn_section_valid(ms, pfn); - - return memblock_is_memory(addr); -} -EXPORT_SYMBOL(pfn_valid); - int pfn_is_map_memory(unsigned long pfn) { phys_addr_t addr = PFN_PHYS(pfn); diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index a9b263d4cf9d..d0c4fc506fa3 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1443,6 +1443,15 @@ static inline int pfn_valid(unsigned long pfn) { struct mem_section *ms; + /* + * Ensure the upper PAGE_SHIFT bits are clear in the + * pfn. Else it might lead to false positives when + * some of the upper bits are set, but the lower bits + * match a valid pfn. + */ + if (PHYS_PFN(PFN_PHYS(pfn)) != pfn) + return 0; + if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; ms = __nr_to_section(pfn_to_section_nr(pfn)); -- 2.20.1
