[PATCH v4 3/5] memblock: add memblock_cap_memory_ranges for multiple ranges

Mike Rapoport rppt at linux.ibm.com
Mon Apr 15 12:09:42 PDT 2019


Hi,

On Mon, Apr 15, 2019 at 06:57:23PM +0800, Chen Zhou wrote:
> The memblock_cap_memory_range() removes all the memory except the
> range passed to it. Extend this function to receive memblock_type
> with the regions that should be kept.
> 
> Enable this function in arm64 for reservation of multiple regions
> for the crash kernel.
> 
> Signed-off-by: Chen Zhou <chenzhou10 at huawei.com>
> Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>

I didn't work on this version, please drop the signed-off.

> ---
>  include/linux/memblock.h |  1 +
>  mm/memblock.c            | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 47e3c06..180877c 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -446,6 +446,7 @@ phys_addr_t memblock_start_of_DRAM(void);
>  phys_addr_t memblock_end_of_DRAM(void);
>  void memblock_enforce_memory_limit(phys_addr_t memory_limit);
>  void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);
> +void memblock_cap_memory_ranges(struct memblock_type *regions_to_keep);
>  void memblock_mem_limit_remove_map(phys_addr_t limit);
>  bool memblock_is_memory(phys_addr_t addr);
>  bool memblock_is_map_memory(phys_addr_t addr);
> diff --git a/mm/memblock.c b/mm/memblock.c
> index f315eca..9661807 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1697,6 +1697,51 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
>  			base + size, PHYS_ADDR_MAX);
>  }
>  
> +void __init memblock_cap_memory_ranges(struct memblock_type *regions_to_keep)
> +{
> +	int start_rgn[INIT_MEMBLOCK_REGIONS], end_rgn[INIT_MEMBLOCK_REGIONS];
> +	int i, j, ret, nr = 0;
> +	struct memblock_region *regs = regions_to_keep->regions;
> +
> +	for (i = 0; i < regions_to_keep->cnt; i++) {
> +		ret = memblock_isolate_range(&memblock.memory, regs[i].base,
> +				regs[i].size, &start_rgn[i], &end_rgn[i]);
> +		if (ret)
> +			break;
> +		nr++;
> +	}
> +	if (!nr)
> +		return;
> +
> +	/* remove all the MAP regions */
> +	for (i = memblock.memory.cnt - 1; i >= end_rgn[nr - 1]; i--)
> +		if (!memblock_is_nomap(&memblock.memory.regions[i]))
> +			memblock_remove_region(&memblock.memory, i);
> +
> +	for (i = nr - 1; i > 0; i--)
> +		for (j = start_rgn[i] - 1; j >= end_rgn[i - 1]; j--)
> +			if (!memblock_is_nomap(&memblock.memory.regions[j]))
> +				memblock_remove_region(&memblock.memory, j);
> +
> +	for (i = start_rgn[0] - 1; i >= 0; i--)
> +		if (!memblock_is_nomap(&memblock.memory.regions[i]))
> +			memblock_remove_region(&memblock.memory, i);
> +
> +	/* truncate the reserved regions */
> +	memblock_remove_range(&memblock.reserved, 0, regs[0].base);
> +
> +	for (i = nr - 1; i > 0; i--) {
> +		phys_addr_t remove_base = regs[i - 1].base + regs[i - 1].size;
> +		phys_addr_t remove_size = regs[i].base - remove_base;
> +
> +		memblock_remove_range(&memblock.reserved, remove_base,
> +				remove_size);
> +	}
> +
> +	memblock_remove_range(&memblock.reserved,
> +			regs[nr - 1].base + regs[nr - 1].size, PHYS_ADDR_MAX);
> +}
> +

I've double-checked and I see no problem with using
for_each_mem_range_rev() iterators for removing some ranges. And with them
this functions becomes much clearer and more efficient.

Can you please check if the below patch works for you?

>From e25e6c9cd94a01abac124deacc66e5d258fdbf7c Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt at linux.ibm.com>
Date: Wed, 10 Apr 2019 16:02:32 +0300
Subject: [PATCH] memblock: extend memblock_cap_memory_range to multiple ranges

The memblock_cap_memory_range() removes all the memory except the range
passed to it. Extend this function to receive an array of memblock_regions
that should be kept. This allows switching to simple iteration over
memblock arrays with 'for_each_mem_range_rev' to remove the unneeded memory.

Enable use of this function in arm64 for reservation of multiple regions for
the crash kernel.

Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>
---
 arch/arm64/mm/init.c     | 34 ++++++++++++++++++++++++----------
 include/linux/memblock.h |  2 +-
 mm/memblock.c            | 44 ++++++++++++++++++++------------------------
 3 files changed, 45 insertions(+), 35 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 6bc1350..8665d29 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -64,6 +64,10 @@ EXPORT_SYMBOL(memstart_addr);
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
 #ifdef CONFIG_KEXEC_CORE
+
+/* at most two crash kernel regions, low_region and high_region */
+#define CRASH_MAX_USABLE_RANGES	2
+
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *
@@ -280,9 +284,9 @@ early_param("mem", early_mem);
 static int __init early_init_dt_scan_usablemem(unsigned long node,
 		const char *uname, int depth, void *data)
 {
-	struct memblock_region *usablemem = data;
-	const __be32 *reg;
-	int len;
+	struct memblock_type *usablemem = data;
+	const __be32 *reg, *endp;
+	int len, nr = 0;
 
 	if (depth != 1 || strcmp(uname, "chosen") != 0)
 		return 0;
@@ -291,22 +295,32 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
 	if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
 		return 1;
 
-	usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
-	usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
+	endp = reg + (len / sizeof(__be32));
+	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
+		unsigned long base = dt_mem_next_cell(dt_root_addr_cells, &reg);
+		unsigned long size = dt_mem_next_cell(dt_root_size_cells, &reg);
 
+		if (memblock_add_range(usablemem, base, size, NUMA_NO_NODE,
+				       MEMBLOCK_NONE))
+			return 0;
+		if (++nr >= CRASH_MAX_USABLE_RANGES)
+			break;
+	}
 	return 1;
 }
 
 static void __init fdt_enforce_memory_region(void)
 {
-	struct memblock_region reg = {
-		.size = 0,
+	struct memblock_region usable_regions[CRASH_MAX_USABLE_RANGES];
+	struct memblock_type usablemem = {
+		.max = CRASH_MAX_USABLE_RANGES,
+		.regions = usable_regions,
 	};
 
-	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
+	of_scan_flat_dt(early_init_dt_scan_usablemem, &usablemem);
 
-	if (reg.size)
-		memblock_cap_memory_range(reg.base, reg.size);
+	if (usablemem.cnt)
+		memblock_cap_memory_ranges(usablemem.regions, usablemem.cnt);
 }
 
 void __init arm64_memblock_init(void)
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 294d5d8..f5c029b 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -404,7 +404,7 @@ phys_addr_t memblock_mem_size(unsigned long limit_pfn);
 phys_addr_t memblock_start_of_DRAM(void);
 phys_addr_t memblock_end_of_DRAM(void);
 void memblock_enforce_memory_limit(phys_addr_t memory_limit);
-void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);
+void memblock_cap_memory_ranges(struct memblock_region *regions, int count);
 void memblock_mem_limit_remove_map(phys_addr_t limit);
 bool memblock_is_memory(phys_addr_t addr);
 bool memblock_is_map_memory(phys_addr_t addr);
diff --git a/mm/memblock.c b/mm/memblock.c
index e7665cf..8d4d060 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1605,36 +1605,31 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
 			      PHYS_ADDR_MAX);
 }
 
-void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
-{
-	int start_rgn, end_rgn;
-	int i, ret;
-
-	if (!size)
-		return;
-
-	ret = memblock_isolate_range(&memblock.memory, base, size,
-						&start_rgn, &end_rgn);
-	if (ret)
-		return;
-
-	/* remove all the MAP regions */
-	for (i = memblock.memory.cnt - 1; i >= end_rgn; i--)
-		if (!memblock_is_nomap(&memblock.memory.regions[i]))
-			memblock_remove_region(&memblock.memory, i);
+void __init memblock_cap_memory_ranges(struct memblock_region *regions,
+				       int count)
+{
+	struct memblock_type regions_to_keep = {
+		.max = count,
+		.cnt = count,
+		.regions = regions,
+	};
+	phys_addr_t start, end;
+	u64 i;
 
-	for (i = start_rgn - 1; i >= 0; i--)
-		if (!memblock_is_nomap(&memblock.memory.regions[i]))
-			memblock_remove_region(&memblock.memory, i);
+	/* truncate memory while skipping NOMAP regions */
+	for_each_mem_range_rev(i, &memblock.memory, &regions_to_keep,
+			       NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL)
+		memblock_remove(start, end);
 
 	/* truncate the reserved regions */
-	memblock_remove_range(&memblock.reserved, 0, base);
-	memblock_remove_range(&memblock.reserved,
-			base + size, PHYS_ADDR_MAX);
+	for_each_mem_range_rev(i, &memblock.reserved, &regions_to_keep,
+			       NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL)
+		memblock_remove_range(&memblock.reserved, start, end);
 }
 
 void __init memblock_mem_limit_remove_map(phys_addr_t limit)
 {
+	struct memblock_region region = { 0 };
 	phys_addr_t max_addr;
 
 	if (!limit)
@@ -1646,7 +1641,8 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit)
 	if (max_addr == PHYS_ADDR_MAX)
 		return;
 
-	memblock_cap_memory_range(0, max_addr);
+	region.size = max_addr;
+	memblock_cap_memory_ranges(&region, 1);
 }
 
 static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
-- 
2.7.4


-- 
Sincerely yours,
Mike.




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