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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A740AC4338F for ; Mon, 2 Aug 2021 02:39:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DEA7610A0 for ; Mon, 2 Aug 2021 02:39:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231818AbhHBCjR (ORCPT ); Sun, 1 Aug 2021 22:39:17 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:7910 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229915AbhHBCjQ (ORCPT ); Sun, 1 Aug 2021 22:39:16 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GdMYH6z5zz82x6; Mon, 2 Aug 2021 10:35:15 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 2 Aug 2021 10:39:05 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 2 Aug 2021 10:39:04 +0800 Subject: Re: [PATCH v2 1/3] vmalloc: Choose a better start address in vm_area_register_early() To: Catalin Marinas CC: Will Deacon , Andrey Ryabinin , Andrey Konovalov , Dmitry Vyukov , , , , References: <20210720025105.103680-1-wangkefeng.wang@huawei.com> <20210720025105.103680-2-wangkefeng.wang@huawei.com> <20210801152311.GB28489@arm.com> From: Kefeng Wang Message-ID: <0de87be6-7041-c58b-a01f-3d6e3333c6f0@huawei.com> Date: Mon, 2 Aug 2021 10:39:04 +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: <20210801152311.GB28489@arm.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/8/1 23:23, Catalin Marinas wrote: > On Tue, Jul 20, 2021 at 10:51:03AM +0800, Kefeng Wang wrote: >> There are some fixed locations in the vmalloc area be reserved >> in ARM(see iotable_init()) and ARM64(see map_kernel()), but for >> pcpu_page_first_chunk(), it calls vm_area_register_early() and >> choose VMALLOC_START as the start address of vmap area which >> could be conflicted with above address, then could trigger a >> BUG_ON in vm_area_add_early(). >> >> Let's choose the end of existing address range in vmlist as the >> start address instead of VMALLOC_START to avoid the BUG_ON. >> >> Signed-off-by: Kefeng Wang >> --- >> mm/vmalloc.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >> index d5cd52805149..a98cf97f032f 100644 >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -2238,12 +2238,14 @@ void __init vm_area_add_early(struct vm_struct *vm) >> */ >> void __init vm_area_register_early(struct vm_struct *vm, size_t align) >> { >> - static size_t vm_init_off __initdata; >> + unsigned long vm_start = VMALLOC_START; >> + struct vm_struct *tmp; >> unsigned long addr; >> >> - addr = ALIGN(VMALLOC_START + vm_init_off, align); >> - vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START; >> + for (tmp = vmlist; tmp; tmp = tmp->next) >> + vm_start = (unsigned long)tmp->addr + tmp->size; >> >> + addr = ALIGN(vm_start, align); >> vm->addr = (void *)addr; >> >> vm_area_add_early(vm); > Is there a risk of breaking other architectures? It doesn't look like to > me but I thought I'd ask. Before this patch, vm_init_off is to record the offset from VMALLOC_START, but it use VMALLOC_START as start address on the function vm_area_register_early() called firstly,  this will cause the BUG_ON. With this patch, the most important change is that we choose the start address via dynamic calculate the 'start' address by traversing the list. [wkf@localhost linux-next]$ git grep vm_area_register_early arch/alpha/mm/init.c: vm_area_register_early(&console_remap_vm, PAGE_SIZE); arch/x86/xen/p2m.c:     vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); mm/percpu.c:    vm_area_register_early(&vm, PAGE_SIZE); [wkf@localhost linux-next]$ git grep vm_area_add_early arch/arm/mm/ioremap.c:  vm_area_add_early(vm); arch/arm64/mm/mmu.c:    vm_area_add_early(vma); x86/alpha won't call vm_area_add_early(), only arm64 could call both vm_area_add_early() and vm_area_register_early() when this patchset is merged. so it won't break other architectures. > > Also, instead of always picking the end, could we search for a range > that fits? We only need a space in vmalloc range,  using end or a range in the middle is not different. >