arm, arm64: move free_unused_memmap() to generic mm

ARM and ARM64 free unused parts of the memory map just before the
initialization of the page allocator. To allow holes in the memory map both
architectures overload pfn_valid() and define HAVE_ARCH_PFN_VALID.

Allowing holes in the memory map for FLATMEM may be useful for small
machines, such as ARC and m68k and will enable those architectures to cease
using DISCONTIGMEM and still support more than one memory bank.

Move the functions that free unused memory map to generic mm and enable
them in case HAVE_ARCH_PFN_VALID=y.

Link: https://lkml.kernel.org/r/20201101170454.9567-10-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Meelis Roos <mroos@linux.ee>
Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 68 deletions

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 095540667f0f..3d8328277bec 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -430,71 +430,6 @@ void __init bootmem_init(void)
 	memblock_dump_all();
 }
 
-#ifndef CONFIG_SPARSEMEM_VMEMMAP
-static inline void free_memmap(unsigned long start_pfn, unsigned long end_pfn)
-{
-	struct page *start_pg, *end_pg;
-	unsigned long pg, pgend;
-
-	/*
-	 * Convert start_pfn/end_pfn to a struct page pointer.
-	 */
-	start_pg = pfn_to_page(start_pfn - 1) + 1;
-	end_pg = pfn_to_page(end_pfn - 1) + 1;
-
-	/*
-	 * Convert to physical addresses, and round start upwards and end
-	 * downwards.
-	 */
-	pg = (unsigned long)PAGE_ALIGN(__pa(start_pg));
-	pgend = (unsigned long)__pa(end_pg) & PAGE_MASK;
-
-	/*
-	 * If there are free pages between these, free the section of the
-	 * memmap array.
-	 */
-	if (pg < pgend)
-		memblock_free(pg, pgend - pg);
-}
-
-/*
- * The mem_map array can get very big. Free the unused area of the memory map.
- */
-static void __init free_unused_memmap(void)
-{
-	unsigned long start, end, prev_end = 0;
-	int i;
-
-	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, NULL) {
-#ifdef CONFIG_SPARSEMEM
-		/*
-		 * Take care not to free memmap entries that don't exist due
-		 * to SPARSEMEM sections which aren't present.
-		 */
-		start = min(start, ALIGN(prev_end, PAGES_PER_SECTION));
-#endif
-		/*
-		 * If we had a previous bank, and there is a space between the
-		 * current bank and the previous, free it.
-		 */
-		if (prev_end && prev_end < start)
-			free_memmap(prev_end, start);
-
-		/*
-		 * Align up here since the VM subsystem insists that the
-		 * memmap entries are valid from the bank end aligned to
-		 * MAX_ORDER_NR_PAGES.
-		 */
-		prev_end = ALIGN(end, MAX_ORDER_NR_PAGES);
-	}
-
-#ifdef CONFIG_SPARSEMEM
-	if (!IS_ALIGNED(prev_end, PAGES_PER_SECTION))
-		free_memmap(prev_end, ALIGN(prev_end, PAGES_PER_SECTION));
-#endif
-}
-#endif	/* !CONFIG_SPARSEMEM_VMEMMAP */
-
 /*
  * mem_init() marks the free areas in the mem_map and tells us how much memory
  * is free.  This is done after various parts of the system have claimed their
@@ -510,9 +445,6 @@ void __init mem_init(void)
 
 	set_max_mapnr(max_pfn - PHYS_PFN_OFFSET);
 
-#ifndef CONFIG_SPARSEMEM_VMEMMAP
-	free_unused_memmap();
-#endif
 	/* this will put all unused low memory onto the freelists */
 	memblock_free_all();