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Date: Wed, 10 Apr 2019 16:09:18 +0300
From: Mike Rapoport <rppt@...ux.ibm.com>
To: Chen Zhou <chenzhou10@...wei.com>
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
ebiederm@...ssion.com, catalin.marinas@....com,
will.deacon@....com, akpm@...ux-foundation.org,
ard.biesheuvel@...aro.org, horms@...ge.net.au,
takahiro.akashi@...aro.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
linux-mm@...ck.org, wangkefeng.wang@...wei.com
Subject: Re: [PATCH v3 3/4] arm64: kdump: support more than one crash kernel
regions
Hi,
On Tue, Apr 09, 2019 at 06:28:18PM +0800, Chen Zhou wrote:
> After commit (arm64: kdump: support reserving crashkernel above 4G),
> there may be two crash kernel regions, one is below 4G, the other is
> above 4G.
>
> Crash dump kernel reads more than one crash kernel regions via a dtb
> property under node /chosen,
> linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>
>
> Signed-off-by: Chen Zhou <chenzhou10@...wei.com>
> ---
> arch/arm64/mm/init.c | 66 ++++++++++++++++++++++++++++++++++++++++--------
> include/linux/memblock.h | 6 +++++
> mm/memblock.c | 7 ++---
> 3 files changed, 66 insertions(+), 13 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 3bebddf..0f18665 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -65,6 +65,11 @@ 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
> +#define LOW_REGION_IDX 0
> +#define HIGH_REGION_IDX 1
> +
> /*
> * reserve_crashkernel() - reserves memory for crash kernel
> *
> @@ -297,8 +302,8 @@ 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;
> + const __be32 *reg, *endp;
> + int len, nr = 0;
>
> if (depth != 1 || strcmp(uname, "chosen") != 0)
> return 0;
> @@ -307,22 +312,63 @@ 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, ®);
> - usablemem->size = dt_mem_next_cell(dt_root_size_cells, ®);
> + endp = reg + (len / sizeof(__be32));
> + while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
> + usablemem[nr].base = dt_mem_next_cell(dt_root_addr_cells, ®);
> + usablemem[nr].size = dt_mem_next_cell(dt_root_size_cells, ®);
> +
> + if (++nr >= CRASH_MAX_USABLE_RANGES)
> + break;
> + }
>
> return 1;
> }
>
> static void __init fdt_enforce_memory_region(void)
> {
> - struct memblock_region reg = {
> - .size = 0,
> - };
> + int i, cnt = 0;
> + struct memblock_region regs[CRASH_MAX_USABLE_RANGES];
I only now noticed that fdt_enforce_memory_region() uses memblock_region to
pass the ranges around. If we'd switch to memblock_type instead, the
implementation of memblock_cap_memory_ranges() would be really
straightforward. Can you check if the below patch works for you?
>From e476d584098e31273af573e1a78e308880c5cf28 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@...ux.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 recieve memblock_type with the
regions that should be kept. This allows switching to simple iteration over
memblock arrays with 'for_each_mem_range' to remove the unneeded memory.
Enable use of this function in arm64 for reservation of multile regions for
the crash kernel.
Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
---
arch/arm64/mm/init.c | 34 ++++++++++++++++++++++++----------
include/linux/memblock.h | 2 +-
mm/memblock.c | 45 ++++++++++++++++++++++-----------------------
3 files changed, 47 insertions(+), 34 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 6bc1350..30a496f 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, ®);
- usablemem->size = dt_mem_next_cell(dt_root_size_cells, ®);
+ 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, ®);
+ unsigned long size = dt_mem_next_cell(dt_root_size_cells, ®);
+ 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, ®);
+ 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);
}
void __init arm64_memblock_init(void)
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 294d5d8..a803ae9 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_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 e7665cf..83d84d4 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1605,36 +1605,34 @@ 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)
+void __init memblock_cap_memory_ranges(struct memblock_type *regions_to_keep)
{
- 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);
+ 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(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(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 rgn = {
+ .base = 0,
+ };
+
+ struct memblock_type region_to_keep = {
+ .cnt = 1,
+ .max = 1,
+ .regions = &rgn,
+ };
+
phys_addr_t max_addr;
if (!limit)
@@ -1646,7 +1644,8 @@ 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_to_keep.regions[0].size = max_addr;
+ memblock_cap_memory_ranges(®ion_to_keep);
}
static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
--
2.7.4
--
Sincerely yours,
Mike.
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