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 13033CCD18E for ; Wed, 15 Oct 2025 06:51:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=bMz8FVtJcY2GE7liN4RGxuFk/amg60OKiAU3IoMdOSA=; b=lV0YUFz/42LgY0THpC2w+vBkmn Mcwtjf82ukuEZEnPRw+QiwI4Phuxn5DdtJWWXiN6L+k7q+/mEvwyUJp0EmA2gvx20Ml0yF9yNbX34 8+cTSCDngvZTlV3MvuKxHffqnjP+Dt3/k4tYb2OoFif8b0hVWkQvZiS5Gps+3TACs+m7y8lHgIccP RZEq4cx3W0sZghBc/BYaOZQ0jxEtKKJjqpkiBsq92mP7/odjsLxUda9rh9o18e3owiG1vOOx2hMEF MSuc/LyhfWbYCAtndBz9Jb+zQijYpFgbYC5BwfS5oZOPrJNlLbo3KY1AkrLdEvc09P/5EtocLs4q+ R8VTL5kA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v8vLj-00000000e0O-1pHb; Wed, 15 Oct 2025 06:51:03 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v8vLg-00000000dzx-3vdY for linux-arm-kernel@lists.infradead.org; Wed, 15 Oct 2025 06:51:02 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BAF671A32; Tue, 14 Oct 2025 23:50:50 -0700 (PDT) Received: from [10.163.67.182] (unknown [10.163.67.182]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2FE483F6A8; Tue, 14 Oct 2025 23:50:54 -0700 (PDT) Message-ID: Date: Wed, 15 Oct 2025 12:20:51 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] arm64: mm: relax VM_ALLOW_HUGE_VMAP if BBML2_NOABORT is supported To: Yang Shi , ryan.roberts@arm.com, cl@gentwo.org, catalin.marinas@arm.com, will@kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20251013232803.3065100-1-yang@os.amperecomputing.com> <20251013232803.3065100-3-yang@os.amperecomputing.com> Content-Language: en-US From: Dev Jain In-Reply-To: <20251013232803.3065100-3-yang@os.amperecomputing.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251014_235101_015734_F9EE0A2C X-CRM114-Status: GOOD ( 20.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 14/10/25 4:57 am, Yang Shi wrote: > When changing permissions for vmalloc area, VM_ALLOW_HUGE_VMAP area is > exclueded because kernel can't split the va mapping if it is called on > partial range. > It is no longer true if the machines support BBML2_NOABORT after commit > a166563e7ec3 ("arm64: mm: support large block mapping when rodata=full"). > So we can relax this restriction and update the comments accordingly. > > Fixes: a166563e7ec3 ("arm64: mm: support large block mapping when rodata=full") > Signed-off-by: Yang Shi > --- > arch/arm64/mm/pageattr.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index c21a2c319028..b4dcae6273a8 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -157,13 +157,13 @@ static int change_memory_common(unsigned long addr, int numpages, > > /* > * Kernel VA mappings are always live, and splitting live section > - * mappings into page mappings may cause TLB conflicts. This means > - * we have to ensure that changing the permission bits of the range > - * we are operating on does not result in such splitting. > + * mappings into page mappings may cause TLB conflicts on the machines > + * which don't support BBML2_NOABORT. > * > * Let's restrict ourselves to mappings created by vmalloc (or vmap). > - * Disallow VM_ALLOW_HUGE_VMAP mappings to guarantee that only page > - * mappings are updated and splitting is never needed. > + * Disallow VM_ALLOW_HUGE_VMAP mappings if the systems don't support > + * BBML2_NOABORT to guarantee that only page mappings are updated and > + * splitting is never needed on those machines. > * > * So check whether the [addr, addr + size) interval is entirely > * covered by precisely one VM area that has the VM_ALLOC flag set. > @@ -171,7 +171,8 @@ static int change_memory_common(unsigned long addr, int numpages, > area = find_vm_area((void *)addr); > if (!area || > end > (unsigned long)kasan_reset_tag(area->addr) + area->size || > - ((area->flags & (VM_ALLOC | VM_ALLOW_HUGE_VMAP)) != VM_ALLOC)) > + !(area->flags & VM_ALLOC) || ((area->flags & VM_ALLOW_HUGE_VMAP) && > + !system_supports_bbml2_noabort())) > return -EINVAL; > > if (!numpages) This will conflict with my upcoming vmalloc-huge series, so best to leave it to me, I already have this included :)