[PATCH v2 17/20] mm: free_area_init: allow defining max_zone_pfn in descending order

Mike Rapoport
2020-04-29T12:11:23Z

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.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
arch/arc/mm/init.c | 36 +++++++-----------------------------
mm/page_alloc.c | 24 +++++++++++++++++++-----
2 files changed, 26 insertions(+), 34 deletions(-)

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index 0920c969c466..41eb9be1653c 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -63,11 +63,13 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)

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_arch(u64 base, u64 size)
*/
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);
}

/*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d35ca0996a09..98a47f90065a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7408,7 +7408,8 @@ static void check_for_memory(pg_data_t *pgdat, int nid)
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,
@@ -7418,13 +7419,26 @@ void __init free_area_init(unsigned long *max_zone_pfn)

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;
}
--
2.26.1