linux-kernel - [PATCH v2 3/4] mips: kdump: Reserve extra memory for crash dump

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Date:   Thu, 22 Apr 2021 10:24:33 +0800
From:   Youling Tang <tangyouling@...ngson.cn>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Jiaxun Yang <jiaxun.yang@...goat.com>, Baoquan He <bhe@...hat.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Jinyang He <hejinyang@...ngson.cn>, kexec@...ts.infradead.org,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/4] mips: kdump: Reserve extra memory for crash dump

From: Huacai Chen <chenhc@...ote.com>

Traditionally, MIPS's contiguous low memory can be as less as 256M, so
crashkernel=X@Y may be unable to large enough in some cases. Moreover,
for the "multi numa node + sparse memory model" case, it is attempt to
allocate section_mem_maps on every node. Thus, if the total memory of a
node is more than 1GB, we reserve the top 128MB for the capture kernel.

This 128M will be reserved only if the following conditions are met:
1. The configuration option CONFIG_KEXEC is y.
2. A valid "crashkernel=" parameter has been added to the command line.
3. The total memory of a node is greater than 1G.

Signed-off-by: Huacai Chen <chenhuacai@...nel.org>
Signed-off-by: Youling Tang <tangyouling@...ngson.cn>
---
v2:
- New patch.

 arch/mips/kernel/setup.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 1bc8a9cc..af2c860 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -492,6 +492,25 @@ static void __init request_crashkernel(struct resource *res)
 			(unsigned long)(resource_size(&crashk_res) >> 20),
 			(unsigned long)(crashk_res.start  >> 20));
 }
+
+/*
+ * Traditionally, MIPS's contiguous low memory is 256M, so crashkernel=X@Y is
+ * unable to be large enough in some cases. Thus, if the total memory of a node
+ * is more than 1GB, we reserve the top 128MB for the capture kernel.
+ */
+static void reserve_crashm_region(int node, unsigned long s0, unsigned long e0)
+{
+	if (crashk_res.start == crashk_res.end)
+		return;
+
+	if ((e0 - s0) <= (SZ_1G >> PAGE_SHIFT))
+		return;
+
+	s0 = e0 - (SZ_128M >> PAGE_SHIFT);
+
+	memblock_reserve(PFN_PHYS(s0), (e0 - s0) << PAGE_SHIFT);
+}
+
 #else /* !defined(CONFIG_KEXEC)		*/
 static void __init mips_parse_crashkernel(void)
 {
@@ -500,6 +519,10 @@ static void __init mips_parse_crashkernel(void)
 static void __init request_crashkernel(struct resource *res)
 {
 }
+
+static void reserve_crashm_region(int node, unsigned long s0, unsigned long e0)
+{
+}
 #endif /* !defined(CONFIG_KEXEC)  */
 
 static void __init check_kernel_sections_mem(void)
@@ -627,6 +650,9 @@ static void __init bootcmdline_init(void)
  */
 static void __init arch_mem_init(char **cmdline_p)
 {
+	unsigned int node;
+	unsigned long start_pfn, end_pfn;
+
 	/* call board setup routine */
 	plat_mem_setup();
 	memblock_set_bottom_up(true);
@@ -666,6 +692,12 @@ static void __init arch_mem_init(char **cmdline_p)
 	if (crashk_res.start != crashk_res.end)
 		memblock_reserve(crashk_res.start, resource_size(&crashk_res));
 #endif
+
+	for_each_online_node(node) {
+		get_pfn_range_for_nid(node, &start_pfn, &end_pfn);
+		reserve_crashm_region(node, start_pfn, end_pfn);
+	}
+
 	device_tree_init();
 
 	/*
-- 
2.1.0