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b=lXOXgSf3CTPIOLuzygqugyz/m3Kblgh8MJs48+8iMsrQjzG/qreHEh6jO47pbs2re 3Uurw9Fnc9zQFse+AdXIM57kpmzdsdr1ooxzZqIvRiCYXeJlt07zQ8jYqlkv8E8OLB BUay2w1iDEsNeXgnApmBVX/YkfaRTnV5iO8RYzy2pKRTix0uDbT98nUisN3fax9Vm9 AWVEq0WetPaNznRKVC8P1r3D+YP4JRnSVN+EpNFOKu1I600ottqeNwplAml/t5VSHC N0BsVidOkEyx3RLTv4wvcJq0/hAHxAWeZytzszlFcTY2vEhrcSIW2Q919aFyhUE1q/ R2sd0rh6zc5tw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v3 2/4] riscv: Add support for kexec handover (KHO) Reply-To: sashiko-reviews@lists.linux.dev To: "Chen Pei" , pjw@kernel.org, palmer@dabbelt.com, alex@ghiti.fr, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, graf@amazon.com, shuah@kernel.org Cc: guoren@kernel.org, linux-mm@kvack.org, kexec@lists.infradead.org In-Reply-To: <20261106071459.2003-3-cp0613@linux.alibaba.com> References: <20261106071459.2003-1-cp0613@linux.alibaba.com> <20261106071459.2003-3-cp0613@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sat, 07 Nov 2026 07:15:33 +0000 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C3FAF20006 X-Stat-Signature: bnm3wfawae8y13o4unc68d8m1ycfktgi X-Rspam-User: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794035735-527964 X-HE-Meta: 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 mJ2c5c4r 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 2 potential issues to consider: - [High] riscv: kho: BUG_ON() in linear_mapping_pa_to_va() during efi_init() - [Medium] riscv: kho: kho_reserve_bootmem() fails when DRAM starts at or above 4 GiB -- commit 9359adbe095f746cadb4028ea618b75e0af09036 Author: Chen Pei riscv: Add support for kexec handover (KHO) This commit enables ARCH_SUPPORTS_KEXEC_HANDOVER on 64-bit RISC-V systems with MMU support. > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index bde1f1885038f..bffef6b903e13 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -1125,6 +1125,9 @@ config ARCH_SELECTS_KEXEC_FILE > config ARCH_SUPPORTS_KEXEC_PURGATORY > def_bool ARCH_SUPPORTS_KEXEC_FILE > =20 > +config ARCH_SUPPORTS_KEXEC_HANDOVER > + def_bool 64BIT && MMU > + > config ARCH_SUPPORTS_CRASH_DUMP > def_bool y [Severity: High] Does enabling KEXEC_HANDOVER here hit BUG_ON(!kernel_map.va_pa_offset) in linear_mapping_pa_to_va() during early boot on UEFI systems with CONFIG_DEBUG_VIRTUAL=3Dy? In setup_arch(), parse_dtb() populates kho_in.fdt_phys, and then efi_init() runs before paging_init(): arch/riscv/kernel/setup.c:setup_arch() { ... parse_dtb(); ... efi_init(); paging_init(); ... } efi_init() -> reserve_regions() -> is_kho_boot() -> kho_get_fdt() calls phys_to_virt(kho_in.fdt_phys), which translates to __va() -> linear_mapping_pa_to_va(). On 64-bit RISC-V, kernel_map.va_pa_offset is still 0 at that point because it is not initialized until paging_init() -> setup_bootmem(). [Severity: Medium] Can kho_reserve_bootmem() fail on 64-bit RISC-V systems where DRAM starts at or above 4 GiB? RISC-V does not define ARCH_LOW_ADDRESS_LIMIT, so it defaults to 0xffffffffUL in include/linux/memblock.h. When all DRAM starts at or above 4 GiB, bootmem_size_update() sets bootmem_size_lowmem to 0, and kho_reserve_bootmem() unconditionally calls memblock_phys_alloc_range() below ARCH_LOW_ADDRESS_LIMIT: kernel/liveupdate/kexec_handover.c:kho_reserve_bootmem() { ... size =3D bootmem_size_lowmem; addr =3D memblock_phys_alloc_range(size, BOOTMEM_ALIGNMENT_BYTES, 0, ARCH_LOW_ADDRESS_LIMIT); if (!addr) { pr_err("Failed to reserve lowmem bootmem\n"); goto err_free_bootmem_desc; } ... } Because no memory exists below 4 GiB, the allocation returns 0 and aborts KHO initialization. Conversely, when all DRAM lies below 4 GiB, bootmem_size_global is 0 and kho_reserve_bootmem() records a 0-byte entry in kho_bootmem[], which causes kho_walk_bootmem() to build an inverted struct resource with end =3D start - 1. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261106071459.2003= -1-cp0613@linux.alibaba.com?part=3D2