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Wed, 02 Sep 2026 00:32:24 -0700 (PDT) From: Wandun Chen To: catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, robh@kernel.org, saravanak@kernel.org, akpm@linux-foundation.org, baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, m.szyprowski@samsung.com Cc: mark.rutland@arm.com, kernel@xen0n.name, alex@ghiti.fr, hpa@zytor.com, 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 v6 04/10] crash_core: serialize crash header preparation against hotplug Date: Wed, 2 Sep 2026 15:31:10 +0800 Message-ID: <20260902073116.802752-5-chenwandun1@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260902073116.802752-1-chenwandun1@gmail.com> References: <20260902073116.802752-1-chenwandun1@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0A5EDA000A X-Stat-Signature: ihsrg1od7e6zig63hux7thgydbhmi6we X-HE-Tag: 1788334345-294873 X-HE-Meta: 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 xWhcmK5u 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 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] --- arch/x86/kernel/crash.c | 2 +- include/linux/crash_core.h | 2 ++ kernel/crash_core.c | 17 +++++++++++++++-- 3 files changed, 18 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index e681ec9cf1dc..284d78bc3fd0 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 77285ae3ce60..3adee1ae120c 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -338,8 +339,8 @@ 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; @@ -376,6 +377,18 @@ 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