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 573DC1C32 for ; Sun, 30 Mar 2025 07:13:11 +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=1743318794; cv=none; b=pZJLHsBzNXxDyjQihHa+zYO3+dOCsnIozRPc6nbrHfRdt/PVePL/DGjWogsNanLE4SjnRnrIJVYAKyBOIzT+XP6HdEXnSmD4DsiltvxXITSR9SMOnJFN1OiGpn3lQzkKie0XXEiXbZGRtj9H8yLITcpmXHl3dbdHFl4XEBRke3w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743318794; c=relaxed/simple; bh=kC5EuvQqPTPDTi2iHA7lYR1aDAdViGDeGegx1E2A1VE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iaCbUjZtf/OVGTgx2koXw/atEvwhujCVFTKuY6vZdi2QAdObSx8bieFRmTzjxDNFYdeIkthjftLEDZogJpw7/En2g3YX20xNd9BG0igQyj8OXZRg7NWsZwL9YKWjWnJf3+cYzIuTf3LDfDPlMb/C9paXO/WKkDhRnuXp95CEgb8= 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 B43911007; Sun, 30 Mar 2025 00:13:14 -0700 (PDT) Received: from [10.163.43.124] (unknown [10.163.43.124]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D89353F694; Sun, 30 Mar 2025 00:13:05 -0700 (PDT) Message-ID: Date: Sun, 30 Mar 2025 12:43:01 +0530 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 To: Mike Rapoport 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, ryan.roberts@arm.com, urezki@gmail.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250328062103.79462-1-dev.jain@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29/03/25 4:20 am, 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. Sorry, mistakenly used them interchangeably. I'll fix this. > >> 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 >> --- >> 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) Thanks! > > >> * 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 >> >