From nobody Mon Feb 9 16:17:03 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E05A7C7EE2E for ; Sat, 27 May 2023 12:36:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232591AbjE0Mga (ORCPT ); Sat, 27 May 2023 08:36:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232569AbjE0MgN (ORCPT ); Sat, 27 May 2023 08:36:13 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1C06194 for ; Sat, 27 May 2023 05:35:53 -0700 (PDT) Received: from dggpemm500006.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4QT1Qr6x5XzLpvb; Sat, 27 May 2023 20:32:52 +0800 (CST) Received: from thunder-town.china.huawei.com (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Sat, 27 May 2023 20:35:50 +0800 From: Zhen Lei To: Eric Biederman , Baoquan He , , CC: Zhen Lei , Michael Holzheu , Andrew Morton , Amerigo Wang Subject: [PATCH 6/6] kexec: enable kexec_crash_size to support two crash kernel regions Date: Sat, 27 May 2023 20:34:39 +0800 Message-ID: <20230527123439.772-7-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.37.3.windows.1 In-Reply-To: <20230527123439.772-1-thunder.leizhen@huawei.com> References: <20230527123439.772-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The crashk_low_res should be considered by /sys/kernel/kexec_crash_size to support two crash kernel regions. Since crashk_res manages the memory with high address and crashk_low_res manages the memory with low address, crashk_low_res is shrunken only when all crashk_res is shrunken. And because when there is only one crash kernel region, crashk_res is always used. Therefore, if all crashk_res is shrunken and crashk_low_res still exists, swap them. Signed-off-by: Zhen Lei Acked-by: Baoquan He --- kernel/kexec_core.c | 43 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 38 insertions(+), 5 deletions(-) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index e82bc6d6634136a..c1d50f6566300d9 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1091,6 +1091,11 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs) } } =20 +static inline resource_size_t crash_resource_size(const struct resource *r= es) +{ + return !res->end ? 0 : resource_size(res); +} + ssize_t crash_get_memory_size(void) { ssize_t size =3D 0; @@ -1098,8 +1103,8 @@ ssize_t crash_get_memory_size(void) if (!kexec_trylock()) return -EBUSY; =20 - if (crashk_res.end !=3D crashk_res.start) - size =3D resource_size(&crashk_res); + size +=3D crash_resource_size(&crashk_res); + size +=3D crash_resource_size(&crashk_low_res); =20 kexec_unlock(); return size; @@ -1135,7 +1140,7 @@ int __crash_shrink_memory(struct resource *old_res, u= nsigned long new_size) int crash_shrink_memory(unsigned long new_size) { int ret =3D 0; - unsigned long old_size; + unsigned long old_size, low_size; =20 if (!kexec_trylock()) return -EBUSY; @@ -1144,14 +1149,42 @@ int crash_shrink_memory(unsigned long new_size) ret =3D -ENOENT; goto unlock; } - old_size =3D !crashk_res.end ? 0 : resource_size(&crashk_res); + + low_size =3D crash_resource_size(&crashk_low_res); + old_size =3D crash_resource_size(&crashk_res) + low_size; new_size =3D roundup(new_size, KEXEC_CRASH_MEM_ALIGN); if (new_size >=3D old_size) { ret =3D (new_size =3D=3D old_size) ? 0 : -EINVAL; goto unlock; } =20 - ret =3D __crash_shrink_memory(&crashk_res, new_size); + /* + * (low_size > new_size) implies that low_size is greater than zero. + * This also means that if low_size is zero, the else branch is taken. + * + * If low_size is greater than 0, (low_size > new_size) indicates that + * crashk_low_res also needs to be shrunken. Otherwise, only crashk_res + * needs to be shrunken. + */ + if (low_size > new_size) { + ret =3D __crash_shrink_memory(&crashk_res, 0); + if (ret) + goto unlock; + + ret =3D __crash_shrink_memory(&crashk_low_res, new_size); + } else { + ret =3D __crash_shrink_memory(&crashk_res, new_size - low_size); + } + + /* Swap crashk_res and crashk_low_res if needed */ + if (!crashk_res.end && crashk_low_res.end) { + crashk_res.start =3D crashk_low_res.start; + crashk_res.end =3D crashk_low_res.end; + release_resource(&crashk_low_res); + crashk_low_res.start =3D 0; + crashk_low_res.end =3D 0; + insert_resource(&iomem_resource, &crashk_res); + } =20 unlock: kexec_unlock(); --=20 2.25.1