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Wed, 21 Oct 2026 17:01:50 +0800 (CST) Received: from kwepemk200008.china.huawei.com (unknown [7.202.194.74]) by mail.maildlp.com (Postfix) with ESMTPS id 1B4A840563; Wed, 21 Oct 2026 17:13:10 +0800 (CST) Received: from [10.67.110.68] (10.67.110.68) by kwepemk200008.china.huawei.com (7.202.194.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45; Wed, 21 Oct 2026 17:13:08 +0800 Message-ID: <12e4e687-1ff0-41b2-bdf8-7f48b29e1f2f@huawei.com> Date: Wed, 21 Oct 2026 17:13:07 +0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 3/8] crash_core: serialize crash header preparation against hotplug To: Wandun Chen , , , , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20261021083011.2170525-1-chenwandun1@gmail.com> <20261021083011.2170525-4-chenwandun1@gmail.com> From: Jinjie Ruan In-Reply-To: <20261021083011.2170525-4-chenwandun1@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemk200008.china.huawei.com (7.202.194.74) X-Stat-Signature: ga6q6y4cqobkezpzejm4seqxnfkmenhf X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 1FACD100007 X-Rspam-User: X-HE-Tag: 1792573994-891661 X-HE-Meta: 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 v10+n71f 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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 在 2026/10/21 16:30, Wandun Chen 写道: > 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(); I think this patch conflicts with my changes and would also conflict with the implementation of arm64 crash hotplug. https://lore.kernel.org/all/20260921090450.807575-15-ruanjinjie@huawei.com/ arm64 crash hotplug: https://lore.kernel.org/all/20260918100442.3841135-18-ruanjinjie@huawei.com/ > + > + 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 -- Best regards, Jinjie