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    Subject[PATCH 08/13] arm: remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
    Date
    From: Mike Rapoport <rppt@linux.ibm.com>

    ARM is the only architecture that defines CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
    which in turn enables memmap_valid_within() function that is intended to
    verify existence of struct page associated with a pfn when there are holes
    in the memory map.

    However, the ARCH_HAS_HOLES_MEMORYMODEL also enables HAVE_ARCH_PFN_VALID
    and arch-specific pfn_valid() implementation that also deals with the holes
    in the memory map.

    The only two users of memmap_valid_within() call this function after
    a call to pfn_valid() so the memmap_valid_within() check becomes redundant.

    Remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL and memmap_valid_within() and rely
    entirely on ARM's implementation of pfn_valid() that is now enabled
    unconditionally.

    Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
    ---
    Documentation/vm/memory-model.rst | 3 +--
    arch/arm/Kconfig | 8 ++------
    arch/arm/mach-bcm/Kconfig | 1 -
    arch/arm/mach-davinci/Kconfig | 1 -
    arch/arm/mach-exynos/Kconfig | 1 -
    arch/arm/mach-highbank/Kconfig | 1 -
    arch/arm/mach-omap2/Kconfig | 1 -
    arch/arm/mach-s5pv210/Kconfig | 1 -
    arch/arm/mach-tango/Kconfig | 1 -
    fs/proc/kcore.c | 2 --
    include/linux/mmzone.h | 31 -------------------------------
    mm/mmzone.c | 14 --------------
    mm/vmstat.c | 4 ----
    13 files changed, 3 insertions(+), 66 deletions(-)

    diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst
    index 9daadf9faba1..ce398a7dc6cd 100644
    --- a/Documentation/vm/memory-model.rst
    +++ b/Documentation/vm/memory-model.rst
    @@ -51,8 +51,7 @@ call :c:func:`free_area_init` function. Yet, the mappings array is not
    usable until the call to :c:func:`memblock_free_all` that hands all the
    memory to the page allocator.

    -If an architecture enables `CONFIG_ARCH_HAS_HOLES_MEMORYMODEL` option,
    -it may free parts of the `mem_map` array that do not cover the
    +An architecture may free parts of the `mem_map` array that do not cover the
    actual physical pages. In such case, the architecture specific
    :c:func:`pfn_valid` implementation should take the holes in the
    `mem_map` into account.
    diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
    index fe2f17eb2b50..83adc46c1e67 100644
    --- a/arch/arm/Kconfig
    +++ b/arch/arm/Kconfig
    @@ -25,7 +25,7 @@ config ARM
    select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
    select ARCH_HAVE_CUSTOM_GPIO_H
    select ARCH_HAS_GCOV_PROFILE_ALL
    - select ARCH_KEEP_MEMBLOCK if HAVE_ARCH_PFN_VALID || KEXEC
    + select ARCH_KEEP_MEMBLOCK
    select ARCH_MIGHT_HAVE_PC_PARPORT
    select ARCH_NO_SG_CHAIN if !ARM_HAS_SG_CHAIN
    select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
    @@ -519,7 +519,6 @@ config ARCH_S3C24XX
    config ARCH_OMAP1
    bool "TI OMAP1"
    depends on MMU
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ARCH_OMAP
    select CLKDEV_LOOKUP
    select CLKSRC_MMIO
    @@ -1479,9 +1478,6 @@ config OABI_COMPAT
    UNPREDICTABLE (in fact it can be predicted that it won't work
    at all). If in doubt say N.

    -config ARCH_HAS_HOLES_MEMORYMODEL
    - bool
    -
    config ARCH_SELECT_MEMORY_MODEL
    bool

    @@ -1493,7 +1489,7 @@ config ARCH_SPARSEMEM_ENABLE
    select SPARSEMEM_STATIC if SPARSEMEM

    config HAVE_ARCH_PFN_VALID
    - def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM
    + def_bool y

    config HIGHMEM
    bool "High Memory Support"
    diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig
    index ae790908fc74..9b594ae98153 100644
    --- a/arch/arm/mach-bcm/Kconfig
    +++ b/arch/arm/mach-bcm/Kconfig
    @@ -211,7 +211,6 @@ config ARCH_BRCMSTB
    select BCM7038_L1_IRQ
    select BRCMSTB_L2_IRQ
    select BCM7120_L2_IRQ
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ZONE_DMA if ARM_LPAE
    select SOC_BRCMSTB
    select SOC_BUS
    diff --git a/arch/arm/mach-davinci/Kconfig b/arch/arm/mach-davinci/Kconfig
    index f56ff8c24043..de11030748d0 100644
    --- a/arch/arm/mach-davinci/Kconfig
    +++ b/arch/arm/mach-davinci/Kconfig
    @@ -5,7 +5,6 @@ menuconfig ARCH_DAVINCI
    depends on ARCH_MULTI_V5
    select DAVINCI_TIMER
    select ZONE_DMA
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select PM_GENERIC_DOMAINS if PM
    select PM_GENERIC_DOMAINS_OF if PM && OF
    select REGMAP_MMIO
    diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig
    index d2d249706ebb..56d272967fc0 100644
    --- a/arch/arm/mach-exynos/Kconfig
    +++ b/arch/arm/mach-exynos/Kconfig
    @@ -8,7 +8,6 @@
    menuconfig ARCH_EXYNOS
    bool "Samsung Exynos"
    depends on ARCH_MULTI_V7
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ARCH_SUPPORTS_BIG_ENDIAN
    select ARM_AMBA
    select ARM_GIC
    diff --git a/arch/arm/mach-highbank/Kconfig b/arch/arm/mach-highbank/Kconfig
    index 1bc68913d62c..9de38ce8124f 100644
    --- a/arch/arm/mach-highbank/Kconfig
    +++ b/arch/arm/mach-highbank/Kconfig
    @@ -2,7 +2,6 @@
    config ARCH_HIGHBANK
    bool "Calxeda ECX-1000/2000 (Highbank/Midway)"
    depends on ARCH_MULTI_V7
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ARCH_SUPPORTS_BIG_ENDIAN
    select ARM_AMBA
    select ARM_ERRATA_764369 if SMP
    diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
    index 3ee7bdff86b2..89fe1572c142 100644
    --- a/arch/arm/mach-omap2/Kconfig
    +++ b/arch/arm/mach-omap2/Kconfig
    @@ -94,7 +94,6 @@ config SOC_DRA7XX
    config ARCH_OMAP2PLUS
    bool
    select ARCH_HAS_BANDGAP
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ARCH_HAS_RESET_CONTROLLER
    select ARCH_OMAP
    select CLKSRC_MMIO
    diff --git a/arch/arm/mach-s5pv210/Kconfig b/arch/arm/mach-s5pv210/Kconfig
    index 95d4e8284866..d644b45bc29d 100644
    --- a/arch/arm/mach-s5pv210/Kconfig
    +++ b/arch/arm/mach-s5pv210/Kconfig
    @@ -8,7 +8,6 @@
    config ARCH_S5PV210
    bool "Samsung S5PV210/S5PC110"
    depends on ARCH_MULTI_V7
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ARM_VIC
    select CLKSRC_SAMSUNG_PWM
    select COMMON_CLK_SAMSUNG
    diff --git a/arch/arm/mach-tango/Kconfig b/arch/arm/mach-tango/Kconfig
    index 25b2fd434861..a9eeda36aeb1 100644
    --- a/arch/arm/mach-tango/Kconfig
    +++ b/arch/arm/mach-tango/Kconfig
    @@ -3,7 +3,6 @@ config ARCH_TANGO
    bool "Sigma Designs Tango4 (SMP87xx)"
    depends on ARCH_MULTI_V7
    # Cortex-A9 MPCore r3p0, PL310 r3p2
    - select ARCH_HAS_HOLES_MEMORYMODEL
    select ARM_ERRATA_754322
    select ARM_ERRATA_764369 if SMP
    select ARM_ERRATA_775420
    diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
    index e502414b3556..4d2e64e9016c 100644
    --- a/fs/proc/kcore.c
    +++ b/fs/proc/kcore.c
    @@ -193,8 +193,6 @@ kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
    return 1;

    p = pfn_to_page(pfn);
    - if (!memmap_valid_within(pfn, p, page_zone(p)))
    - return 1;

    ent = kmalloc(sizeof(*ent), GFP_KERNEL);
    if (!ent)
    diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
    index 876600a6e891..7385871768d4 100644
    --- a/include/linux/mmzone.h
    +++ b/include/linux/mmzone.h
    @@ -1440,37 +1440,6 @@ void sparse_init(void);
    #define pfn_valid_within(pfn) (1)
    #endif

    -#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
    -/*
    - * pfn_valid() is meant to be able to tell if a given PFN has valid memmap
    - * associated with it or not. This means that a struct page exists for this
    - * pfn. The caller cannot assume the page is fully initialized in general.
    - * Hotplugable pages might not have been onlined yet. pfn_to_online_page()
    - * will ensure the struct page is fully online and initialized. Special pages
    - * (e.g. ZONE_DEVICE) are never onlined and should be treated accordingly.
    - *
    - * In FLATMEM, it is expected that holes always have valid memmap as long as
    - * there is valid PFNs either side of the hole. In SPARSEMEM, it is assumed
    - * that a valid section has a memmap for the entire section.
    - *
    - * However, an ARM, and maybe other embedded architectures in the future
    - * free memmap backing holes to save memory on the assumption the memmap is
    - * never used. The page_zone linkages are then broken even though pfn_valid()
    - * returns true. A walker of the full memmap must then do this additional
    - * check to ensure the memmap they are looking at is sane by making sure
    - * the zone and PFN linkages are still valid. This is expensive, but walkers
    - * of the full memmap are extremely rare.
    - */
    -bool memmap_valid_within(unsigned long pfn,
    - struct page *page, struct zone *zone);
    -#else
    -static inline bool memmap_valid_within(unsigned long pfn,
    - struct page *page, struct zone *zone)
    -{
    - return true;
    -}
    -#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
    -
    #endif /* !__GENERATING_BOUNDS.H */
    #endif /* !__ASSEMBLY__ */
    #endif /* _LINUX_MMZONE_H */
    diff --git a/mm/mmzone.c b/mm/mmzone.c
    index 4686fdc23bb9..f337831affc2 100644
    --- a/mm/mmzone.c
    +++ b/mm/mmzone.c
    @@ -72,20 +72,6 @@ struct zoneref *__next_zones_zonelist(struct zoneref *z,
    return z;
    }

    -#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
    -bool memmap_valid_within(unsigned long pfn,
    - struct page *page, struct zone *zone)
    -{
    - if (page_to_pfn(page) != pfn)
    - return false;
    -
    - if (page_zone(page) != zone)
    - return false;
    -
    - return true;
    -}
    -#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
    -
    void lruvec_init(struct lruvec *lruvec)
    {
    enum lru_list lru;
    diff --git a/mm/vmstat.c b/mm/vmstat.c
    index 698bc0bc18d1..e292e63afebf 100644
    --- a/mm/vmstat.c
    +++ b/mm/vmstat.c
    @@ -1503,10 +1503,6 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
    if (!page)
    continue;

    - /* Watch for unexpected holes punched in the memmap */
    - if (!memmap_valid_within(pfn, page, zone))
    - continue;
    -
    if (page_zone(page) != zone)
    continue;

    --
    2.28.0
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