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Wed, 21 Oct 2026 01:31:12 -0700 (PDT) From: Wandun Chen To: robh@kernel.org, baoquan.he@linux.dev, rppt@kernel.org, m.szyprowski@samsung.com Cc: catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, chenhuacai@kernel.org, kernel@xen0n.name, 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, x86@kernel.org, hpa@zytor.com, saravanak@kernel.org, akpm@linux-foundation.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, iommu@lists.linux.dev Subject: [PATCH v9 3/8] crash_core: serialize crash header preparation against hotplug Date: Wed, 21 Oct 2026 16:30:06 +0800 Message-ID: <20261021083011.2170525-4-chenwandun1@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261021083011.2170525-1-chenwandun1@gmail.com> References: <20261021083011.2170525-1-chenwandun1@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E65B22000A X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: ccw715o1im67ae3k68eo8fgen5kjeca7 X-HE-Tag: 1792571474-405662 X-HE-Meta: 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 T6qVwzJc 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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 From: Wandun Chen crash_prepare_headers() counts memory ranges before populating the allocated crash_mem array. The weak implementation used by ARM64, RISC-V and LoongArch walks memblock.memory, while x86 performs the same two-pass operation over system RAM resources. Concurrent memory hotplug can change range source between the two walks and make the populate pass overflow cmem->ranges. Take device_hotplug_lock when preparing crash headers during kexec_file_load(). The x86/riscv memory hotplug path already takes device_hotplug_lock, so call __crash_prepare_headers() directly to avoid recursive locking. Sashiko reported this issue in [1]. Fixes: 3751e728cef2 ("arm64: kexec_file: add crash dump support") Fixes: 1bcca8620a91 ("LoongArch: Add crash dump support for kexec_file") Fixes: 8acea455fafa ("RISC-V: Support for kexec_file on panic") Fixes: dd5f726076cc ("kexec: support for kexec on panic using new system call") Signed-off-by: Wandun Chen Link: https://sashiko.dev/#/message/20260806101002.1F84E1F000E9@smtp.kernel.org [1] Acked-by: Baoquan He --- arch/riscv/kernel/crash.c | 2 +- arch/x86/kernel/crash.c | 2 +- include/linux/crash_core.h | 2 ++ kernel/crash_core.c | 17 +++++++++++++++-- 4 files changed, 19 insertions(+), 4 deletions(-) diff --git a/arch/riscv/kernel/crash.c b/arch/riscv/kernel/crash.c index fe5a4b306aae..ac8df2edf2a7 100644 --- a/arch/riscv/kernel/crash.c +++ b/arch/riscv/kernel/crash.c @@ -70,7 +70,7 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) * Create the new elfcorehdr reflecting the changes to CPU and/or * memory resources. */ - if (crash_prepare_headers(true, &elfbuf, &elfsz, NULL)) { + if (__crash_prepare_headers(true, &elfbuf, &elfsz, NULL)) { pr_err("unable to create new elfcorehdr"); goto out; } diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index e6f23933a6df..bef008a0cb22 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -465,7 +465,7 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) * Create the new elfcorehdr reflecting the changes to CPU and/or * memory resources. */ - if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz, NULL)) { + if (__crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz, NULL)) { pr_err("unable to create new elfcorehdr"); goto out; } diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index bc087124cd78..28e7a81cf263 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -61,6 +61,8 @@ extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_ma void **addr, unsigned long *sz); extern int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz, unsigned long *nr_mem_ranges); +int __crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz, + unsigned long *nr_mem_ranges); extern int crash_exclude_core_ranges(struct crash_mem **cmem); struct kimage; diff --git a/kernel/crash_core.c b/kernel/crash_core.c index faa0f22dbb41..8a861a946e26 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -344,8 +345,8 @@ int crash_exclude_core_ranges(struct crash_mem **cmem) return 0; } -int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz, - unsigned long *nr_mem_ranges) +int __crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz, + unsigned long *nr_mem_ranges) { unsigned int max_nr_ranges; struct crash_mem *cmem; @@ -382,6 +383,18 @@ int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz, return ret; } +int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz, + unsigned long *nr_mem_ranges) +{ + int ret; + + lock_device_hotplug(); + ret = __crash_prepare_headers(need_kernel_map, addr, sz, nr_mem_ranges); + unlock_device_hotplug(); + + return ret; +} + /** * crash_exclude_mem_range - exclude a mem range for existing ranges * @mem: mem->range contains an array of ranges sorted in ascending order -- 2.43.0