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 AB4712192FB; Thu, 29 May 2025 09:02:38 +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=1748509360; cv=none; b=u4CCie66OJvbytzcWFXiqNZtz1ymuVQlqG41+v0SAkslHkYZtK7c8OwNaOUskKcVXcHFYkvCJ+oMOCYnkt8cUjHXo+SvpPHgSNFNh+dUNTuiOdGr2lpx9EbbbD+CSdCVBLFbjmERX828G+oWG2WWU4Vet/+bDsGpi+fzNQCLenA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748509360; c=relaxed/simple; bh=DXcA32gLvtkB+1oDhLo8ikwLTnpgTyUtZRvK1bpu+3g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MXyUKNiPDl5KXhzcnOGOk8lh3WwVjYsRYjNK5gsyCftXPglh30jkl1nHLT24ethki3JWlm5W1FUriK8Sdw2s/2feKCJruA17wa6L9O7NIfzExcyVcavRPMq/iqBZOllJKEjYCgB7PVxvBONE3zEtCFMyza/3ncIqx/IBMdfiv1U= 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 E0632176A; Thu, 29 May 2025 02:02:15 -0700 (PDT) Received: from [10.163.62.34] (unknown [10.163.62.34]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 024513F5A1; Thu, 29 May 2025 02:02:25 -0700 (PDT) Message-ID: <7b9a9ad4-7a7a-4e99-ba72-f5be0f609a21@arm.com> Date: Thu, 29 May 2025 14:32:23 +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 v3] arm64: Restrict pagetable teardown to avoid false warning To: Dev Jain , catalin.marinas@arm.com, will@kernel.org Cc: david@redhat.com, ryan.roberts@arm.com, mark.rutland@arm.com, yang@os.amperecomputing.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org References: <20250527082633.61073-1-dev.jain@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20250527082633.61073-1-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/27/25 13:56, Dev Jain wrote: > Commit 9c006972c3fe removes the pxd_present() checks because the caller > checks pxd_present(). But, in case of vmap_try_huge_pud(), the caller only > checks pud_present(); pud_free_pmd_page() recurses on each pmd through > pmd_free_pte_page(), wherein the pmd may be none. Thus it is possible to > hit a warning in the latter, since pmd_none => !pmd_table(). Thus, add > a pmd_present() check in pud_free_pmd_page(). > > This problem was found by code inspection. > > Fixes: 9c006972c3fe (arm64: mmu: drop pXd_present() checks from pXd_free_pYd_table()) > Cc: > Reported-by: Ryan Roberts > Acked-by: David Hildenbrand > Signed-off-by: Dev Jain > --- > This patch is based on 6.15-rc6. > > v2->v3: > - Use pmdp_get() > > v1->v2: > - Enforce check in caller > > arch/arm64/mm/mmu.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index ea6695d53fb9..5a9bf291c649 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1286,7 +1286,8 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr) > next = addr; > end = addr + PUD_SIZE; > do { > - pmd_free_pte_page(pmdp, next); > + if (pmd_present(pmdp_get(pmdp))) This code path is only called for the kernel mapping. Hence should pmd_valid() be used instead of pmd_present() which also checks for present invalid scenarios as well ? > + pmd_free_pte_page(pmdp, next); > } while (pmdp++, next += PMD_SIZE, next != end); > > pud_clear(pudp);