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Message-ID: <20260204093728.1447527-4-ruanjinjie@huawei.com>
Date: Wed, 4 Feb 2026 17:37:28 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <corbet@....net>, <catalin.marinas@....com>, <will@...nel.org>,
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CC: <ruanjinjie@...wei.com>
Subject: [PATCH v3 3/3] riscv: kexec: Add support for crashkernel CMA reservation
Commit 35c18f2933c5 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510e042 ("kdump:
implement reserve_crashkernel_cma") added CMA support for kdump
crashkernel reservation. This allows the kernel to dynamically allocate
contiguous memory for crash dumping when needed, rather than permanently
reserving a fixed region at boot time.
So extend crashkernel CMA reservation support to riscv. The following
changes are made to enable CMA reservation:
- Parse and obtain the CMA reservation size along with other crashkernel
parameters.
- Call reserve_crashkernel_cma() to allocate the CMA region for kdump.
- Include the CMA-reserved ranges for kdump kernel to use.
- Exclude the CMA-reserved ranges from the crash kernel memory to
prevent them from being exported through /proc/vmcore, which is already
done in the crash core.
Update kernel-parameters.txt to document CMA support for crashkernel on
riscv architecture.
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++--------
arch/riscv/kernel/machine_kexec_file.c | 10 ++++++++--
arch/riscv/mm/init.c | 5 +++--
3 files changed, 19 insertions(+), 12 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 36bb642a7edd..3b92324d3a03 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1119,14 +1119,14 @@ Kernel parameters
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
crashkernel=size[KMG],cma
- [KNL, X86, ARM64, ppc] Reserve additional crash kernel memory from
- CMA. This reservation is usable by the first system's
- userspace memory and kernel movable allocations (memory
- balloon, zswap). Pages allocated from this memory range
- will not be included in the vmcore so this should not
- be used if dumping of userspace memory is intended and
- it has to be expected that some movable kernel pages
- may be missing from the dump.
+ [KNL, X86, ARM64, RISCV, ppc] Reserve additional crash
+ kernel memory from CMA. This reservation is usable by
+ the first system's userspace memory and kernel movable
+ allocations (memory balloon, zswap). Pages allocated
+ from this memory range will not be included in the vmcore
+ so this should not be used if dumping of userspace memory
+ is intended and it has to be expected that some movable
+ kernel pages may be missing from the dump.
A standard crashkernel reservation, as described above,
is still needed to hold the crash kernel and initrd.
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index fec3622a13c9..0e4ac70d5a9a 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -59,9 +59,9 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
{
struct crash_mem *cmem;
unsigned int nr_ranges;
- int ret;
+ int ret, i;
- nr_ranges = 1; /* For exclusion of crashkernel region */
+ nr_ranges = 1 + crashk_cma_cnt; /* For exclusion of crashkernel region */
walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
@@ -74,6 +74,12 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
if (ret)
goto out;
+ for (i = 0; i < crashk_cma_cnt; i++) {
+ cmem->ranges[cmem->nr_ranges].start = crashk_cma_ranges[i].start;
+ cmem->ranges[cmem->nr_ranges].end = crashk_cma_ranges[i].end;
+ cmem->nr_ranges++;
+ }
+
ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
out:
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index addb8a9305be..074d2d5f79ee 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1404,7 +1404,7 @@ static inline void setup_vm_final(void)
*/
static void __init arch_reserve_crashkernel(void)
{
- unsigned long long low_size = 0;
+ unsigned long long low_size = 0, cma_size = 0;
unsigned long long crash_base, crash_size;
bool high = false;
int ret;
@@ -1414,11 +1414,12 @@ static void __init arch_reserve_crashkernel(void)
ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
&crash_size, &crash_base,
- &low_size, NULL, &high);
+ &low_size, &cma_size, &high);
if (ret)
return;
reserve_crashkernel_generic(crash_size, crash_base, low_size, high);
+ reserve_crashkernel_cma(cma_size);
}
void __init paging_init(void)
--
2.34.1
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