From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id EDF661BD517 for ; Sat, 29 Mar 2025 09:47:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743241623; cv=none; b=LCq2nhc4ClteUaokuvn6094xQH/FkwioYFYZRY+2lC4+VlwSEm/RrQoJMQKa4qiSu59egCmp0ooPSrUtkE9lRZa2eJgNAG5y3pTOdtkYmSdCttXdhW+VvHnjPWfXAYKH43/pxZF/5qj/gl0oMIBg+1pes3Wc88uzDAuTaGvGq9k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743241623; c=relaxed/simple; bh=nAdeCiCNLGruzB4lhSr+T1Go6LuomMV55frkoilpjFU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XYz4/9oyQQVpQgGUktznAwknbiww0aJDDe8U8UEw5Fn2wIPxYRjabLuLdQPQfr35uvCS9utKh5G2spdpcpr12rcU+LkFEdZmemaWF+Wi/1XhyMPfqM7h0t43kvyMDlYaiXlPQh3WAYFlxIvT6RjA+CTj0A+hhenerPKF+G0v/ik= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 61765152B; Sat, 29 Mar 2025 02:47:04 -0700 (PDT) Received: from [10.57.87.112] (unknown [10.57.87.112]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DB0943F694; Sat, 29 Mar 2025 02:46:57 -0700 (PDT) Message-ID: Date: Sat, 29 Mar 2025 09:46:56 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm64: pageattr: Explicitly bail out when changing permissions for vmalloc_huge mappings Content-Language: en-GB To: Mike Rapoport , Dev Jain Cc: catalin.marinas@arm.com, will@kernel.org, gshan@redhat.com, steven.price@arm.com, suzuki.poulose@arm.com, tianyaxiong@kylinos.cn, ardb@kernel.org, david@redhat.com, urezki@gmail.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250328062103.79462-1-dev.jain@arm.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 28/03/2025 18:50, Mike Rapoport wrote: > On Fri, Mar 28, 2025 at 11:51:03AM +0530, Dev Jain wrote: >> arm64 uses apply_to_page_range to change permissions for kernel VA mappings, > > for vmalloc mappings ^ > > arm64 does not allow changing permissions to any VA address right now. > >> which does not support changing permissions for leaf mappings. This function >> will change permissions until it encounters a leaf mapping, and will bail >> out. To avoid this partial change, explicitly disallow changing permissions >> for VM_ALLOW_HUGE_VMAP mappings. >> >> Signed-off-by: Dev Jain I wonder if we want a Fixes: tag here? It's certainly a *latent* bug. >> --- >> arch/arm64/mm/pageattr.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c >> index 39fd1f7ff02a..8337c88eec69 100644 >> --- a/arch/arm64/mm/pageattr.c >> +++ b/arch/arm64/mm/pageattr.c >> @@ -96,7 +96,7 @@ static int change_memory_common(unsigned long addr, int numpages, >> * we are operating on does not result in such splitting. >> * >> * Let's restrict ourselves to mappings created by vmalloc (or vmap). >> - * Those are guaranteed to consist entirely of page mappings, and >> + * Disallow VM_ALLOW_HUGE_VMAP vmalloc mappings so that > > I'd keep mention of page mappings in the comment, e.g > > * Disallow VM_ALLOW_HUGE_VMAP mappings to guarantee that only page > * mappings are updated and splitting is never needed. > > With this and changelog updates Ryan asked for > > Reviewed-by: Mike Rapoport (Microsoft) > > >> * splitting is never needed. >> * >> * So check whether the [addr, addr + size) interval is entirely >> @@ -105,7 +105,7 @@ 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)) >> + ((area->flags & (VM_ALLOC | VM_ALLOW_HUGE_VMAP)) != VM_ALLOC)) >> return -EINVAL; >> >> if (!numpages) >> -- >> 2.30.2 >> >