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 6589BC7EE2C for ; Wed, 31 May 2023 01:16:39 +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=tQbIZysiVFGw6QzEs5fR9jZS7qxG47WrejuoMzN8apk=; b=o7BeyAVAUKY7Ag5+jt86B4elq/ OmHbVKjHgYdQ9s/eyBvfGqmK3VM9W2EO+4qkSboIwmaHviaqVyUFmdxZAgllNqg2WAb7sls6VOBTs 7XRQ7aZs47zFs4QUgfm+igKW/K7UANkN+Y9TBCN+8BTp6MKQjKE6q47AU1AyU2c5uZ2WIiD92zx9Y 3LZHFo5kgPq61MFzBnr0KNuoBIXj8PLFx6OCiVUZSYv46WYgNn50cQtuFzik324gDtJYFRcDHGuPX 9rQkSL1tcFh320ejvWZ4VHBGM0gG296ukRiyafAO41FEw1yk1CAKVjlnqse+oDk/dCqZhc5HKglSA ImPUHg7A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q4AS3-00Fh0x-2U; Wed, 31 May 2023 01:16:35 +0000 Received: from szxga01-in.huawei.com ([45.249.212.187]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q4ARz-00FgxG-2p for kexec@lists.infradead.org; Wed, 31 May 2023 01:16:34 +0000 Received: from dggpemm500006.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QWB746xqwzqTYs; Wed, 31 May 2023 09:11:44 +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 09:16:23 +0800 Subject: Re: [PATCH 1/6] kexec: fix a memory leak in crash_shrink_memory() To: Baoquan He CC: Eric Biederman , , , Michael Holzheu , Andrew Morton References: <20230527123439.772-1-thunder.leizhen@huawei.com> <20230527123439.772-2-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <5232350c-7529-eece-c9cb-8a8bbc83a81a@huawei.com> Date: Wed, 31 May 2023 09:16:22 +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: dggems704-chm.china.huawei.com (10.3.19.181) 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-20230530_181632_250518_3005D5BB X-CRM114-Status: GOOD ( 20.84 ) 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 8:13, Baoquan He wrote: > On 05/27/23 at 08:34pm, Zhen Lei wrote: >> If the value of parameter 'new_size' is in the semi-open and semi-closed >> interval (crashk_res.end - KEXEC_CRASH_MEM_ALIGN + 1, crashk_res.end], the >> calculation result of ram_res is: >> ram_res->start = crashk_res.end + 1 >> ram_res->end = crashk_res.end > > If the new_size is smaller than KEXEC_CRASH_MEM_ALIGN, does it make > any sense except of testing purpose? Do we need to fail this kind of > shrinking, or just shrink all the left crash memory? We can't give a fixed value, that is, how much crash memory is reserved to ensure that the capture kernel runs. The size of KEXEC_CRASH_MEM_ALIGN is only one page on non-s390 platforms. So, it's better to keep the code simple, and let the user(administrator) shrink the crash memory reasonably. include/linux/kexec.h #define KEXEC_CRASH_MEM_ALIGN PAGE_SIZE > >> The operation of function insert_resource() fails, and ram_res is not >> added to iomem_resource. As a result, the memory of the control block >> ram_res is leaked. >> >> In fact, on all architectures, the start address and size of crashk_res >> are already aligned by KEXEC_CRASH_MEM_ALIGN. Therefore, we do not need to >> round up crashk_res.start again. Instead, we should round up 'new_size' >> in advance. >> >> Fixes: 6480e5a09237 ("kdump: add missing RAM resource in crash_shrink_memory()") >> Fixes: 06a7f711246b ("kexec: premit reduction of the reserved memory size") >> Signed-off-by: Zhen Lei >> --- >> kernel/kexec_core.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c >> index 3d578c6fefee385..22acee18195a591 100644 >> --- a/kernel/kexec_core.c >> +++ b/kernel/kexec_core.c >> @@ -1122,6 +1122,7 @@ int crash_shrink_memory(unsigned long new_size) >> start = crashk_res.start; >> end = crashk_res.end; >> old_size = (end == 0) ? 0 : end - start + 1; >> + new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN); >> if (new_size >= old_size) { >> ret = (new_size == old_size) ? 0 : -EINVAL; >> goto unlock; >> @@ -1133,9 +1134,7 @@ int crash_shrink_memory(unsigned long new_size) >> goto unlock; >> } >> >> - start = roundup(start, KEXEC_CRASH_MEM_ALIGN); >> - end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN); >> - >> + end = start + new_size; >> crash_free_reserved_phys_range(end, crashk_res.end); >> >> if ((start == end) && (crashk_res.parent != NULL)) >> -- >> 2.25.1 >> > > . > -- Regards, Zhen Lei _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec