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 61CA9C7EE23 for ; Wed, 31 May 2023 14:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:CC:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=cEMPN3JQDnsJQF9tWTaYhCDhiJg5XzxG8dlkwXhcgGc=; b=aYbsgVX+RJKsaIjlR4d7WXFnKO to4FLJWNRtvjxuDPevUe8wNFzevpPqiIAkKCUbSrWA4aoWLzmCLIKe/jVz8mvocn0DfCsIMkQS8Q1 cqtIh9cSsC6Lp3MY2tYAdQmXa2ZYeq5Vb2aENIcDZeFzDRYADJZKouCc13he60mhsp34DTS6rXN67 w6DLyecqQkRBbKWDGvP1zZA2gWWT7NlX3HDxof7mhj3nM9CN2flNW7RyIaeAVhZMPWOd8qoCqZYeN 9EJYy4nhajZmkWW3m5oBFF19ErvWv1b9aCpQeg1w5weR08pCoiybfk76HWGLFhvxuAgC9wULCpQ1n 1Mk3rBAw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q4Mlp-000885-3B; Wed, 31 May 2023 14:25:50 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q4Mll-000861-2Z for kexec@lists.infradead.org; Wed, 31 May 2023 14:25:48 +0000 Received: from dggpemm500006.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4QWWgd4jvFzLq8l; Wed, 31 May 2023 22:22:37 +0800 (CST) Received: from [10.174.178.55] (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; Wed, 31 May 2023 22:25:36 +0800 Subject: Re: [PATCH 6/6] kexec: enable kexec_crash_size to support two crash kernel regions To: Baoquan He CC: Eric Biederman , , , Michael Holzheu , Andrew Morton References: <20230527123439.772-1-thunder.leizhen@huawei.com> <20230527123439.772-7-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <955d2ba6-2cb8-7ee1-031f-e9033b32a3c8@huawei.com> Date: Wed, 31 May 2023 22:25:36 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230531_072546_665382_12AFA3F6 X-CRM114-Status: GOOD ( 24.11 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 2023/5/31 17:53, Baoquan He wrote: > On 05/27/23 at 08:34pm, Zhen Lei wrote: >> 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. > > This looks good, otherwise someone else won't stop attempting to add > support of crashk_low_res shrinking. Not sure if this will bring corner > case issue in testing, let's see. For the patch log, I tried to > rephrase, feel free to refer to. > > ===== > The crashk_low_res should be considered by /sys/kernel/kexec_crash_size > to support two crash kernel regions shrinking if existing. > > While doing it, crashk_low_res will only be shrunk when the entire > crashk_res is empty; and if the crashk_res is empty and crahk_low_res > is not, change crashk_low_res to be crashk_res. > ===== > > With the log updated, you can add: > > Acked-by: Baoquan He OK, I will update the log and add Acked-by in v2. > >> >> Signed-off-by: Zhen Lei >> --- >> 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) >> } >> } >> >> +static inline resource_size_t crash_resource_size(const struct resource *res) >> +{ >> + return !res->end ? 0 : resource_size(res); >> +} >> + >> ssize_t crash_get_memory_size(void) >> { >> ssize_t size = 0; >> @@ -1098,8 +1103,8 @@ ssize_t crash_get_memory_size(void) >> if (!kexec_trylock()) >> return -EBUSY; >> >> - if (crashk_res.end != crashk_res.start) >> - size = resource_size(&crashk_res); >> + size += crash_resource_size(&crashk_res); >> + size += crash_resource_size(&crashk_low_res); >> >> kexec_unlock(); >> return size; >> @@ -1135,7 +1140,7 @@ int __crash_shrink_memory(struct resource *old_res, unsigned long new_size) >> int crash_shrink_memory(unsigned long new_size) >> { >> int ret = 0; >> - unsigned long old_size; >> + unsigned long old_size, low_size; >> >> if (!kexec_trylock()) >> return -EBUSY; >> @@ -1144,14 +1149,42 @@ int crash_shrink_memory(unsigned long new_size) >> ret = -ENOENT; >> goto unlock; >> } >> - old_size = !crashk_res.end ? 0 : resource_size(&crashk_res); >> + >> + low_size = crash_resource_size(&crashk_low_res); >> + old_size = crash_resource_size(&crashk_res) + low_size; >> new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN); >> if (new_size >= old_size) { >> ret = (new_size == old_size) ? 0 : -EINVAL; >> goto unlock; >> } >> >> - ret = __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 = __crash_shrink_memory(&crashk_res, 0); >> + if (ret) >> + goto unlock; >> + >> + ret = __crash_shrink_memory(&crashk_low_res, new_size); >> + } else { >> + ret = __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 = crashk_low_res.start; >> + crashk_res.end = crashk_low_res.end; >> + release_resource(&crashk_low_res); >> + crashk_low_res.start = 0; >> + crashk_low_res.end = 0; >> + insert_resource(&iomem_resource, &crashk_res); >> + } >> >> unlock: >> kexec_unlock(); >> -- >> 2.25.1 >> > > . > -- Regards, Zhen Lei _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec