From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 913FEC982D7 for ; Fri, 18 Sep 2026 07:55:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hvrGzctpGGzu8oxKQw3tKpiz4XHwPltvrD9jJxe8Oa4=; b=mNRjNvN0c8fFwl+M//NbEiP5Ot s4prgXO/8QL2pWCVUg09HHjHnqdBETbbAoQhho2snsKoL2EGVRSwwBGNnnESZqSGMYgHsDr/+6zJd y7f4gDaxjIh6WJ1ni+JKsMvec5fjRxqKgROn3jCgcSf/PLdAwcqFK4fRSXGvoevoR5nK8/tqrNQ9/ TFhVEkHUD47JJGWoKNvDPgOIKPxb+bnVEOlgAGsZ0tb9QyiEbYa05RTHYQ7D4DT30csdz9yulBKg0 727j7cBIDBfQq0Pihp7C80A/H+OqeFCyzsWhvv7TOIO/re1suYasZd8DDaPUk641Ed5/3sYSzroZk 3wIbzFJA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x7TR1-0000000Dk3x-091o; Fri, 18 Sep 2026 07:55:03 +0000 Received: from out-180.mta0.migadu.com ([2001:41d0:1004:224b::b4] helo=mta0.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x7TQx-0000000Dk2H-1rgd for kexec@lists.infradead.org; Fri, 18 Sep 2026 07:55:01 +0000 X-Envelope-To: kexec@lists.infradead.org DKIM-Signature: a=rsa-sha256; bh=w1C6Uq5LGLS5v5+hUhhr7wym9SsyY1oKg1mT464GIeo=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789718096; v=1; x=1790322896; b=cQTyQpN72GWh0vFSP2OSSt6OoeLakd/ZFjqWUqc1nDBXGR9zWWRQY06J5rh0UbilUNacd91L F3G0c+rlbShg36Rvo036m6CEVa69aFhh/lsy8ZZlyrfMz+5viDApJz7MxT8J9PiA6S061DCLYQJ YoLnqz8tCr2yoVDATrSIr4e0= X-Envelope-To: kexec@lists.infradead.org Received: by mta11.migadu.com with ESMTPS id ea360a8e458d95f5; Fri, 18 Sep 2026 07:54:56 +0000 X-Mizu-Trace-ID: ea360a8e458d95f5 X-Migadu-Flow: FLOW_OUT Date: Fri, 18 Sep 2026 15:54:48 +0800 From: Baoquan He To: Wandun Chen Cc: 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, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, m.szyprowski@samsung.com, 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: Re: [PATCH v6 04/10] crash_core: serialize crash header preparation against hotplug Message-ID: References: <20260902073116.802752-1-chenwandun1@gmail.com> <20260902073116.802752-5-chenwandun1@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260902073116.802752-5-chenwandun1@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260918_005459_649412_D2B88A9D X-CRM114-Status: GOOD ( 20.73 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 09/02/26 at 03:31pm, Wandun Chen wrote: > 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(-) LGTM, Acked-by: Baoquan He > > 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 >