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h=From:To:Cc:Subject:In-Reply-To:References:Date; b=fB5S3V/LaS0CaeNTSAaiAwX6QQaGxO+OqMWheFNTKPAvbenke7l17ptFB0A7vQjb2 JHvJGb6q3DIEyS/cw6/UVetwp0iUl8hd5HXKpVWv9ECNJNlcHsBYVnzI6Gd4ZtPYE8 oOlobM1tBmOifszaS3w7PmFzmoUXQeWZBv+GoYyzSU3L9tu8HGfXFF1u4zlQ/X1QFI /pul3GxhWLCswfRS3qeRhzKZZaau5Vpf6R+DkpWAyaT2Q1yXLZsqVJ16O4jIO33YnM N4xKOh5r1qKFveuMPJoE7khOS1YZ7HWmA4gBGV344J3/484dRvoqbOlF1M6el/vCzv Cz6tzE5ePpetw== From: Pratyush Yadav To: Greg Thelen Cc: Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Alexander Graf , Andrew Morton , Evangelos Petrongonas , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kho: check fdt_phys in is_kho_boot() In-Reply-To: <20261023054518.3258350-1-gthelen@google.com> (Greg Thelen's message of "Thu, 22 Oct 2026 22:45:18 -0700") References: <20261023054518.3258350-1-gthelen@google.com> Date: Fri, 23 Oct 2026 18:37:33 +0200 Message-ID: <2vxzmrs4fk4y.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Queue-Id: 6577914000A X-Stat-Signature: roaj9sfreayawqqcxhynrotkzjas5czm X-Rspamd-Server: rspam01 X-Spam-Status: No, score=-12.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1792773458-747359 X-HE-Meta: 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 LJ6ypjin K7aMGOIqhOLcXgyblGqGo6e2B12vg5DnGj0iStitK4yc3NvFDe18sytPzySYxsKO3cB/pp1e124fjNRSYQIQZqwQKtCnz0LRDc/2SWcC2OmKSiHWsGXHFNHvs8ZnfH2qHormYSAx3vA+KyRQrvpuO9wnWGDuZmNAFuUNUt7nDvOzr6T0pMVD1tNt8MTHL/osiYxgG/t4BDvYvKDl9iUAnUI1wJP7YwGNLUE668S2zBRhbV+AgUNzcZpdk2fUmEub5etSYNamqnuybpso4ppdjosJfynaWAkfelc5iN1R3t+lrBc6S3Df/2J6vgw== 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 On Thu, Oct 22 2026, Greg Thelen wrote: > During arm64 setup_arch(), efi_init() -> reserve_regions() calls > is_kho_boot() before arm64_memblock_init() initializes memstart_addr. > At this point memstart_addr still holds its initial sentinel value (-1). > > When booting via kexec with KHO enabled, kho_populate() sets > kho_in.fdt_phys from the /chosen FDT node. Calling is_kho_boot() -> > kho_get_fdt() invokes phys_to_virt(kho_in.fdt_phys), which evaluates > PHYS_OFFSET and triggers VM_BUG_ON(memstart_addr & 1) on arm64 kernels > built with CONFIG_DEBUG_VM=y: > > kernel BUG at ./arch/arm64/include/asm/memory.h:377! > Internal error: Oops - BUG: 00000000f2000800 [#1] SMP > Call trace: > is_kho_boot+0x2c/0x38 (P) > efi_init+0x94/0xf8 > setup_arch+0xf0/0x240 > start_kernel+0x84/0x490 > __primary_switched+0x88/0x98 > > Check kho_in.fdt_phys directly in is_kho_boot() instead of calling > kho_get_fdt() so that early boot callers do not invoke phys_to_virt() > before the linear map offset is initialized. > > Fixes: d6d511639185 ("kexec: introduce is_kho_boot()") > Assisted-by: Gemini:gemini-3.8-flash > Signed-off-by: Greg Thelen Reviewed-by: Pratyush Yadav (Google) [...] -- Regards, Pratyush Yadav