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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80B51C77B7E for ; Sat, 27 May 2023 12:36:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232572AbjE0MgN (ORCPT ); Sat, 27 May 2023 08:36:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232538AbjE0MgL (ORCPT ); Sat, 27 May 2023 08:36:11 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB2FB135 for ; Sat, 27 May 2023 05:35:49 -0700 (PDT) Received: from dggpemm500006.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4QT1SR3mYTzLm9y; Sat, 27 May 2023 20:34:15 +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 20:35:46 +0800 From: Zhen Lei To: Eric Biederman , Baoquan He , , CC: Zhen Lei , Michael Holzheu , Andrew Morton , Amerigo Wang Subject: [PATCH 0/6] kexec: enable kexec_crash_size to support two crash kernel regions Date: Sat, 27 May 2023 20:34:33 +0800 Message-ID: <20230527123439.772-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.37.3.windows.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII 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 When crashkernel=X fails to reserve region under 4G, it will fall back to reserve region above 4G and a region of the default size will also be reserved under 4G. Unfortunately, /sys/kernel/kexec_crash_size only supports one crash kernel region now, the user cannot sense the low memory reserved by reading /sys/kernel/kexec_crash_size. Also, low memory cannot be freed by writing this file. For example: resource_size(crashk_res) = 512M resource_size(crashk_low_res) = 256M The result of 'cat /sys/kernel/kexec_crash_size' is 512M, but it should be 768M. When we execute 'echo 0 > /sys/kernel/kexec_crash_size', the size of crashk_res becomes 0 and resource_size(crashk_low_res) is still 256 MB, which is incorrect. 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. Zhen Lei (6): kexec: fix a memory leak in crash_shrink_memory() kexec: delete a useless check in crash_shrink_memory() kexec: clear crashk_res if all its memory has been released kexec: improve the readability of crash_shrink_memory() kexec: add helper __crash_shrink_memory() kexec: enable kexec_crash_size to support two crash kernel regions kernel/kexec_core.c | 92 +++++++++++++++++++++++++++++++-------------- 1 file changed, 64 insertions(+), 28 deletions(-) -- 2.25.1