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riscv: kexec_file: Add support for crashkernel CMA reservation

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Commit 35c18f2933 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510e0 ("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, which was
  already done in of_kexec_alloc_and_setup_fdt().
- Exclude the CMA-reserved ranges from the crash kernel memory to
  prevent them from being exported through /proc/vmcore, which was
  already done in the crash core.

Update kernel-parameters.txt to document CMA support for crashkernel on
riscv architecture.

Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Paul Walmsley <pjw@kernel.org> # arch/riscv
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260629094746.191843-11-ruanjinjie@huawei.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
This commit is contained in:
Jinjie Ruan 2026-06-29 17:47:46 +08:00 committed by Mike Rapoport (Microsoft)
parent c12c63d05d
commit a037fe3c58
3 changed files with 12 additions and 11 deletions
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16
Documentation/admin-guide/kernel-parameters.txt
View File

@ -1089,14 +1089,14 @@ 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.

2
arch/riscv/kernel/machine_kexec_file.c
View File

@ -47,7 +47,7 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
unsigned int arch_get_system_nr_ranges(void)
{
unsigned int nr_ranges = 2; /* For exclusion of crashkernel region */
unsigned int nr_ranges = 2 + crashk_cma_cnt; /* For exclusion of crashkernel region */
walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);

5
arch/riscv/mm/init.c
View File

@ -1320,7 +1320,7 @@ 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;
@ -1330,11 +1330,12 @@ 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)