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Wed, 25 Feb 2026 15:49:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6FE8C116D0; Wed, 25 Feb 2026 15:48:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772034541; bh=pZbjdg50KRzQ422ePCSptr4aHcihMfDCR1tS1O1TEsA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=I532EFVbqE8GHVn3wRpwoiLj0xwBUMITr7qrrtSKpJfbKKP2U/jR/Ni/Xh5FwubUQ jrXuYjxxcGNKvyfvMLOzJTh8WpizKg9jXQ+SIgnrUBkOvnrS/UQQfOCywEFDs+14MG VpQfSsfwndpTxDyTJi1RmrnGh747jM4VFDZfl/9mjXQdhFDHJJ5GhvxFi41iW4ufFr gGwS9ktAeJD8zfB+zANO2NWjTrPQl3JcenJ3IBlSv2Zoo4hbDHTzH7P7+NLi/p1hT8 Ej6MKtOO9hHHUpDMRg6/ChlWZatqgw3xueHfPQ7IsX+e4bjL/EzBH94u6Sx1SQv5NA Q3SR4khoEgBhg== Date: Wed, 25 Feb 2026 17:48:41 +0200 From: Mike Rapoport To: Jinjie Ruan Cc: corbet@lwn.net, skhan@linuxfoundation.org, catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, akpm@linux-foundation.org, bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com, rdunlap@infradead.org, pmladek@suse.com, dapeng1.mi@linux.intel.com, kees@kernel.org, paulmck@kernel.org, lirongqing@baidu.com, arnd@arndb.de, ardb@kernel.org, leitao@debian.org, cfsworks@gmail.com, ryan.roberts@arm.com, sourabhjain@linux.ibm.com, tangyouling@kylinos.cn, eajames@linux.ibm.com, hbathini@linux.ibm.com, ritesh.list@gmail.com, songshuaishuai@tinylab.org, samuel.holland@sifive.com, kevin.brodsky@arm.com, vishal.moola@gmail.com, junhui.liu@pigmoral.tech, coxu@redhat.com, liaoyuanhong@vivo.com, fuqiang.wang@easystack.cn, jbohac@suse.cz, brgerst@gmail.com, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, kexec@lists.infradead.org Subject: Re: [PATCH v6 4/5] arm64: kexec: Add support for crashkernel CMA reservation Message-ID: References: <20260224085342.387996-1-ruanjinjie@huawei.com> <20260224085342.387996-5-ruanjinjie@huawei.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260224085342.387996-5-ruanjinjie@huawei.com> On Tue, Feb 24, 2026 at 04:53:41PM +0800, Jinjie Ruan wrote: > 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, which is already > done in the crash core. > > Update kernel-parameters.txt to document CMA support for crashkernel on > arm64 architecture. > > Acked-by: Ard Biesheuvel > Signed-off-by: Jinjie Ruan > --- > v3: > - Add Acked-by. > v2: > - Free cmem in prepare_elf_headers() > - Add the mtivation. > --- > Documentation/admin-guide/kernel-parameters.txt | 2 +- > arch/arm64/kernel/machine_kexec_file.c | 8 +++++++- > arch/arm64/mm/init.c | 5 +++-- > 3 files changed, 11 insertions(+), 4 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index cb850e5290c2..497f63b76898 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1121,7 +1121,7 @@ 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 c338506a580b..c8862a762eb3 100644 > --- a/arch/arm64/kernel/machine_kexec_file.c > +++ b/arch/arm64/kernel/machine_kexec_file.c > @@ -42,7 +42,7 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image) > #ifdef CONFIG_CRASH_DUMP > 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 */ > phys_addr_t start, end; > u64 i; > > @@ -64,6 +64,12 @@ int arch_crash_populate_cmem(struct crash_mem *cmem) > 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++; > + } Why do we need to add cma ranges here? They are anyway will be excluded in crash_exclude_core_ranges(). The same comment applies to riscv patch. > return 0; > } > #endif > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 96711b8578fd..144e30fe9a75 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 > -- Sincerely yours, Mike.