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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 3FF7FC4338F for ; Wed, 4 Aug 2021 11:14:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C5F061029 for ; Wed, 4 Aug 2021 11:14:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237478AbhHDLOc (ORCPT ); Wed, 4 Aug 2021 07:14:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:55280 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237584AbhHDLOU (ORCPT ); Wed, 4 Aug 2021 07:14:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 224EA60FC4; Wed, 4 Aug 2021 11:14:04 +0000 (UTC) Date: Wed, 4 Aug 2021 12:14:02 +0100 From: Catalin Marinas To: Kefeng Wang Cc: Will Deacon , Andrey Ryabinin , Andrey Konovalov , Dmitry Vyukov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org Subject: Re: [PATCH v2 1/3] vmalloc: Choose a better start address in vm_area_register_early() Message-ID: <20210804111402.GB4857@arm.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0de87be6-7041-c58b-a01f-3d6e3333c6f0@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Catalin