+ mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: free_area_init: allow defining max_zone_pfn in descending order
has been added to the -mm tree.  Its filename is
     mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order.patch

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------------------------------------------------------
From: Mike Rapoport <rppt@linux.ibm.com>
Subject: mm: free_area_init: allow defining max_zone_pfn in descending order

Some architectures (e.g.  ARC) have the ZONE_HIGHMEM zone below the
ZONE_NORMAL.  Allowing free_area_init() parse max_zone_pfn array even it
is sorted in descending order allows using free_area_init() on such
architectures.

Add top -> down traversal of max_zone_pfn array in free_area_init() and
use the latter in ARC node/zone initialization.

Link: http://lkml.kernel.org/r/20200412194859.12663-18-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hoan Tran <Hoan@os.amperecomputing.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arc/mm/init.c |   36 +++++++-----------------------------
 mm/page_alloc.c    |   24 +++++++++++++++++++-----
 2 files changed, 26 insertions(+), 34 deletions(-)

--- a/arch/arc/mm/init.c~mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order
+++ a/arch/arc/mm/init.c
@@ -63,11 +63,13 @@ void __init early_init_dt_add_memory_arc
 
 		low_mem_sz = size;
 		in_use = 1;
+		memblock_add_node(base, size, 0);
 	} else {
 #ifdef CONFIG_HIGHMEM
 		high_mem_start = base;
 		high_mem_sz = size;
 		in_use = 1;
+		memblock_add_node(base, size, 1);
 #endif
 	}
 
@@ -83,8 +85,7 @@ void __init early_init_dt_add_memory_arc
  */
 void __init setup_arch_memory(void)
 {
-	unsigned long zones_size[MAX_NR_ZONES];
-	unsigned long zones_holes[MAX_NR_ZONES];
+	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 
 	init_mm.start_code = (unsigned long)_text;
 	init_mm.end_code = (unsigned long)_etext;
@@ -115,7 +116,6 @@ void __init setup_arch_memory(void)
 	 * the crash
 	 */
 
-	memblock_add_node(low_mem_start, low_mem_sz, 0);
 	memblock_reserve(CONFIG_LINUX_LINK_BASE,
 			 __pa(_end) - CONFIG_LINUX_LINK_BASE);
 
@@ -133,22 +133,7 @@ void __init setup_arch_memory(void)
 	memblock_dump_all();
 
 	/*----------------- node/zones setup --------------------------*/
-	memset(zones_size, 0, sizeof(zones_size));
-	memset(zones_holes, 0, sizeof(zones_holes));
-
-	zones_size[ZONE_NORMAL] = max_low_pfn - min_low_pfn;
-	zones_holes[ZONE_NORMAL] = 0;
-
-	/*
-	 * We can't use the helper free_area_init(zones[]) because it uses
-	 * PAGE_OFFSET to compute the @min_low_pfn which would be wrong
-	 * when our kernel doesn't start at PAGE_OFFSET, i.e.
-	 * PAGE_OFFSET != CONFIG_LINUX_RAM_BASE
-	 */
-	free_area_init_node(0,			/* node-id */
-			    zones_size,		/* num pages per zone */
-			    min_low_pfn,	/* first pfn of node */
-			    zones_holes);	/* holes */
+	max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
 
 #ifdef CONFIG_HIGHMEM
 	/*
@@ -168,20 +153,13 @@ void __init setup_arch_memory(void)
 	min_high_pfn = PFN_DOWN(high_mem_start);
 	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
 
-	zones_size[ZONE_NORMAL] = 0;
-	zones_holes[ZONE_NORMAL] = 0;
-
-	zones_size[ZONE_HIGHMEM] = max_high_pfn - min_high_pfn;
-	zones_holes[ZONE_HIGHMEM] = 0;
-
-	free_area_init_node(1,			/* node-id */
-			    zones_size,		/* num pages per zone */
-			    min_high_pfn,	/* first pfn of node */
-			    zones_holes);	/* holes */
+	max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;
 
 	high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
 	kmap_init();
 #endif
+
+	free_area_init(max_zone_pfn);
 }
 
 /*
--- a/mm/page_alloc.c~mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order
+++ a/mm/page_alloc.c
@@ -7429,7 +7429,8 @@ static void check_for_memory(pg_data_t *
 void __init free_area_init(unsigned long *max_zone_pfn)
 {
 	unsigned long start_pfn, end_pfn;
-	int i, nid;
+	int i, nid, zone;
+	bool descending = false;
 
 	/* Record where the zone boundaries are */
 	memset(arch_zone_lowest_possible_pfn, 0,
@@ -7439,13 +7440,26 @@ void __init free_area_init(unsigned long
 
 	start_pfn = find_min_pfn_with_active_regions();
 
+	/*
+	 * Some architecturs, e.g. ARC may have ZONE_HIGHMEM below
+	 * ZONE_NORMAL. For such cases we allow max_zone_pfn sorted in the
+	 * descending order
+	 */
+	if (MAX_NR_ZONES > 1 && max_zone_pfn[0] > max_zone_pfn[1])
+		descending = true;
+
 	for (i = 0; i < MAX_NR_ZONES; i++) {
-		if (i == ZONE_MOVABLE)
+		if (descending)
+			zone = MAX_NR_ZONES - i - 1;
+		else
+			zone = i;
+
+		if (zone == ZONE_MOVABLE)
 			continue;
 
-		end_pfn = max(max_zone_pfn[i], start_pfn);
-		arch_zone_lowest_possible_pfn[i] = start_pfn;
-		arch_zone_highest_possible_pfn[i] = end_pfn;
+		end_pfn = max(max_zone_pfn[zone], start_pfn);
+		arch_zone_lowest_possible_pfn[zone] = start_pfn;
+		arch_zone_highest_possible_pfn[zone] = end_pfn;
 
 		start_pfn = end_pfn;
 	}
_

Patches currently in -mm which might be from rppt@linux.ibm.com are

mm-memblock-replace-dereferences-of-memblock_regionnid-with-api-calls.patch
mm-make-early_pfn_to_nid-and-related-defintions-close-to-each-other.patch
mm-remove-config_have_memblock_node_map-option.patch
mm-free_area_init-use-maximal-zone-pfns-rather-than-zone-sizes.patch
mm-use-free_area_init-instead-of-free_area_init_nodes.patch
alpha-simplify-detection-of-memory-zone-boundaries.patch
arm-simplify-detection-of-memory-zone-boundaries.patch
arm64-simplify-detection-of-memory-zone-boundaries-for-uma-configs.patch
csky-simplify-detection-of-memory-zone-boundaries.patch
m68k-mm-simplify-detection-of-memory-zone-boundaries.patch
parisc-simplify-detection-of-memory-zone-boundaries.patch
sparc32-simplify-detection-of-memory-zone-boundaries.patch
unicore32-simplify-detection-of-memory-zone-boundaries.patch
xtensa-simplify-detection-of-memory-zone-boundaries.patch
mm-remove-early_pfn_in_nid-and-config_nodes_span_other_nodes.patch
mm-free_area_init-allow-defining-max_zone_pfn-in-descending-order.patch
mm-rename-free_area_init_node-to-free_area_init_memoryless_node.patch
mm-clean-up-free_area_init_node-and-its-helpers.patch
mm-simplify-find_min_pfn_with_active_regions.patch
docs-vm-update-memory-models-documentation.patch