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=-15.4 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,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 695ABC4338F for ; Thu, 5 Aug 2021 12:46:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48168601FC for ; Thu, 5 Aug 2021 12:46:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241460AbhHEMqj (ORCPT ); Thu, 5 Aug 2021 08:46:39 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:12456 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240237AbhHEMqi (ORCPT ); Thu, 5 Aug 2021 08:46:38 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GgStv3bbkzcl9Q; Thu, 5 Aug 2021 20:42:47 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 5 Aug 2021 20:46:22 +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; Thu, 5 Aug 2021 20:46:21 +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> <0de87be6-7041-c58b-a01f-3d6e3333c6f0@huawei.com> <20210804111402.GB4857@arm.com> From: Kefeng Wang Message-ID: Date: Thu, 5 Aug 2021 20:46:20 +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: <20210804111402.GB4857@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: dggems701-chm.china.huawei.com (10.3.19.178) 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 2021/8/4 19:14, Catalin Marinas wrote: > On Mon, Aug 02, 2021 at 10:39:04AM +0800, Kefeng Wang wrote: >> 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. > Thanks for checking. > >>> 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. > I was thinking of making it more future-proof in case one registers a > vm area towards the end of the range. It's fairly easy to pick a range > in the middle now that you are adding a list traversal. ok,  will chose a suitable hole in the vmalloc range. >