From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=113.46.200.224 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792573995; b=LvnBz7n/HhMFAkzbkV/Z42VWm/HgatL/go/xrJQWluHtrJOf7yofWUHABKy/bmoYAG8z BpOYFiGhcUYHCISTwtJYjZzxL0f8137NN1cAYy0X35TuH4uBgDhzI30h8b/gGlF9nb9lA AkMIbdvxyHXuiNRQ8OM1l1GtH4n/0wmb+ql2i9xylI/pw7bx8d6ZQAVkt46ZUDO1tAFX2 N5iFNqUkXll0s0IBijVeHEw08W3C7FdHuGqZj0vZzbGWyOHvddI9yY6/SlSeSFGqj1jll xPmVq8nKGB1B0mCc4anSWaHjZQQxtD1PwBU/x6IKauxyhTf6NbV9v5g8Y/e9mASfW/g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792573995; h=DMARC-Filter:dkim-signature:Received:Received:Received:Message-ID: Date:MIME-Version:User-Agent:Subject:To:CC:References:From: In-Reply-To:Content-Type:Content-Transfer-Encoding:X-Originating-IP: X-ClientProxiedBy; bh=nzADmYKv4GpvdMxYyHHtqrTYHk3osWUIWqWnEfBwJ1o=; b=CvbdU4WgtiKUhIdo8oPGzkazoeA6FoeqnPj8CYzSUvDUbv0F7o46QWh6t5kB/7aeQsSl 7UIo/NhOD9NCWPoFKJU9mrdqkdDCOG1qs/IM0yg1QSruaOD8IRY3C3A1iy0w644IGZeDY abibdoyvbAc9CHwDA0dImWmZc6WcU8zw8+Q3ydOgKABwBjIGnJaaKEVZuFdgQa3QN9Sqo dE7DYe0lmn/kwVH0Wc3qtr9iGsduWsfH5qqkDfvc+18eTgJzcWgHXVf2N9vt0oqON/o9l kZ0MRuIL98Das3X9j0lafBiiIaaAaB2wNvgtpiTawgiykTPjE67tUSAk4gnkHG0/Q0w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass header.d=huawei.com header.i=@huawei.com header.a=rsa-sha256 header.s=dkim header.b=qy05oNmy; arc=none smtp.remote-ip=113.46.200.224 Received: from canpmsgout09.his.huawei.com (canpmsgout09.his.huawei.com [113.46.200.224]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 875F2606A31A; Wed, 21 Oct 2026 09:13:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 875F2606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=huawei.com header.i=@huawei.com header.a=rsa-sha256 header.s=dkim header.b=qy05oNmy dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=nzADmYKv4GpvdMxYyHHtqrTYHk3osWUIWqWnEfBwJ1o=; b=qy05oNmy3wvcAipAQKL4DCStOriRWTyczBtLbfPzPytLSmCWdRpIYENADIsJu88KlAJj0hmjc e1p5428X8KTeWUYB9Vrw2GOPKCj13drNhfpLlgpoC2Z/ybSXrCDzqgJdySA25ihc7Us9rMXLO2x ua/h/PISSyjS5+zO8Dkln2g= Received: from mail.maildlp.com (unknown [172.19.163.200]) by canpmsgout09.his.huawei.com (SkyGuard) with ESMTPS id 4j8jvf2rLvz1cySH; 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-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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) 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