[PATCH 08/13] arm: remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL

From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Greg Ungerer <gerg@linux-m68k.org>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
	Jonathan Corbet <corbet@lwn.net>,
	Matt Turner <mattst88@gmail.com>, Meelis Roos <mroos@linux.ee>,
	Michael Schmitz <schmitzmic@gmail.com>,
	Mike Rapoport <rppt@kernel.org>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Russell King <linux@armlinux.org.uk>,
	Tony Luck <tony.luck@intel.com>,
	Vineet Gupta <vgupta@synopsys.com>, Will Deacon <will@kernel.org>,
	linux-alpha@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
	linux-mm@kvack.org, linux-snps-arc@lists.infradead.org
Subject: [PATCH 08/13] arm: remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
Date: Tue, 27 Oct 2020 13:29:50 +0200	[thread overview]
Message-ID: <20201027112955.14157-9-rppt@kernel.org> (raw)
In-Reply-To: <20201027112955.14157-1-rppt@kernel.org>

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

