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Date:   Tue, 10 May 2022 20:14:56 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Mark-PK Tsai <mark-pk.tsai@...iatek.com>,
        Mike Rapoport <rppt@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Russell King <linux@...linux.org.uk>, kbuild-all@...ts.01.org,
        kernel test robot <lkp@...el.com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        stable@...r.kernel.org
Subject: [PATCH 5.4] arm: remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL

From: Mike Rapoport <rppt@...ux.ibm.com>

commit 5e545df3292fbd3d5963c68980f1527ead2a2b3f upstream.

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.

Link: https://lkml.kernel.org/r/20201101170454.9567-9-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Greg Ungerer <gerg@...ux-m68k.org>
Cc: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@....net>
Cc: Matt Turner <mattst88@...il.com>
Cc: Meelis Roos <mroos@...ux.ee>
Cc: Michael Schmitz <schmitzmic@...il.com>
Cc: Russell King <linux@...linux.org.uk>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Vineet Gupta <vgupta@...opsys.com>
Cc: Will Deacon <will@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Reported-by: kernel test robot <lkp@...el.com>
Fixes: 8dd559d53b3b ("arm: ioremap: don't abuse pfn_valid() to check if pfn is in RAM")
Signed-off-by: Mike Rapoport <rppt@...ux.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       |  2 +-
 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, 4 insertions(+), 66 deletions(-)

diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst
index 58a12376b7df..94db75ba7fbe 100644
--- a/Documentation/vm/memory-model.rst
+++ b/Documentation/vm/memory-model.rst
@@ -52,8 +52,7 @@ wrapper :c:func:`free_area_init`. 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 4b36bbcf5a5b..a1622b9290fd 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -26,7 +26,7 @@ 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
@@ -521,7 +521,6 @@ 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
@@ -1518,9 +1517,6 @@ 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_SPARSEMEM_ENABLE
 	bool
 
@@ -1528,7 +1524,7 @@ config ARCH_SPARSEMEM_DEFAULT
 	def_bool ARCH_SPARSEMEM_ENABLE
 
 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 5e5f1fabc3d4..634d1bc3c011 100644
--- a/arch/arm/mach-bcm/Kconfig
+++ b/arch/arm/mach-bcm/Kconfig
@@ -214,7 +214,6 @@ config ARCH_BRCMSTB
 	select HAVE_ARM_ARCH_TIMER
 	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 02b180ad7245..4d3b7d0418c4 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 9dab1f50a02f..fc01137628e4 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 fdb6743760a2..0211f4aa8cc7 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -94,7 +94,7 @@ 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
 	select GENERIC_IRQ_CHIP
diff --git a/arch/arm/mach-s5pv210/Kconfig b/arch/arm/mach-s5pv210/Kconfig
index 03984a791879..69ff1bb89f38 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 e2ed8e08cc7a..d1cabccc02b7 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 e4f9df955040..b138ddad619e 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1438,37 +1438,6 @@ void memory_present(int nid, unsigned long start, unsigned long end);
 #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 a8222041bd44..240fe2153ca9 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1444,10 +1444,6 @@ 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;
 
-- 
2.34.1

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