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. Crash kernel memory reservation wastes production resources if too large, risks kdump failure if too small, and faces allocation difficulties on fragmented systems due to contiguous block constraints. The new CMA-based crashkernel reservation scheme splits the "large fixed reservation" into a "small fixed region + large CMA dynamic region": the CMA memory is available to userspace during normal operation to avoid waste, and is reclaimed for kdump upon crash—saving memory while improving reliability. So extend crashkernel CMA reservation support to arm64. 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. Update kernel-parameters.txt to document CMA support for crashkernel on arm64 architecture. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- v2: - Free cmem in prepare_elf_headers() - Add the mtivation. --- Documentation/admin-guide/kernel-parameters.txt | 2 +- arch/arm64/kernel/machine_kexec_file.c | 15 ++++++++++++++- arch/arm64/mm/init.c | 5 +++-- 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 1058f2a6d6a8..36bb642a7edd 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1119,7 +1119,7 @@ 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, ppc] Reserve additional crash kernel memory from + [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 diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c index 410060ebd86d..ef6ce9aaba80 100644 --- a/arch/arm64/kernel/machine_kexec_file.c +++ b/arch/arm64/kernel/machine_kexec_file.c @@ -48,7 +48,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz) u64 i; phys_addr_t start, end; - nr_ranges = 2; /* for exclusion of crashkernel region */ + nr_ranges = 2 + crashk_cma_cnt; /* for exclusion of crashkernel region */ for_each_mem_range(i, &start, &end) nr_ranges++; @@ -64,6 +64,12 @@ static int prepare_elf_headers(void **addr, unsigned long *sz) cmem->nr_ranges++; } + 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++; + } + /* Exclude crashkernel region */ ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); if (ret) @@ -75,6 +81,13 @@ static int prepare_elf_headers(void **addr, unsigned long *sz) goto out; } + for (i = 0; i < crashk_cma_cnt; ++i) { + ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start, + crashk_cma_ranges[i].end); + if (ret) + goto out; + } + ret = crash_prepare_elf64_headers(cmem, true, addr, sz); out: diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 524d34a0e921..28165d94af08 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -96,8 +96,8 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit; static void __init arch_reserve_crashkernel(void) { + unsigned long long crash_base, crash_size, cma_size = 0; unsigned long long low_size = 0; - unsigned long long crash_base, crash_size; bool high = false; int ret; @@ -106,11 +106,12 @@ 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); } static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit) -- 2.34.1