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 856ED219302; Thu, 29 May 2025 09:23:02 +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=1748510584; cv=none; b=MaEFHNkU0PuZ01NIXsELfxNzcDTk9hgRCf2AJPvH+rl4UoYVp1nGL1Fb9UPRQF1klpZY7D0fcB8nEOWsx0TlC9kkzaKyMCfYqKIWBXn6SZWVtXmEwEz0/nmx+1+bHbwkxMtVrqgV8ZSkCNWUfb9897fjVr8FrY+XPnLJG2PS5is= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748510584; c=relaxed/simple; bh=sfzG8mKqdZm7/xXGBLDcri6zOyCd7+jQh2rsTTlVB0U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gEZrL3XcKUbIt4y8Se2S9JhaKcjYwaa8EnYWgWBqeji+UlQXxz8NFjB/Pq+zKPLltIUSaAPOfXvVY6w6Nhlcbv+kh/Cs4gC2+3jpW7sc2XjY9Tv07PXwK5LSrRP3qcTkTRtC48FIh6CtUI9IyiwP8AAanmsRH+vpVPpJeKI9A7Q= 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 6D847176A; Thu, 29 May 2025 02:22:45 -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 AC93B3F5A1; Thu, 29 May 2025 02:22:57 -0700 (PDT) Message-ID: <6aacbf96-e685-43fd-b77d-2242d57cb2f3@arm.com> Date: Thu, 29 May 2025 14:52:54 +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))) > + pmd_free_pte_page(pmdp, next); > } while (pmdp++, next += PMD_SIZE, next != end); > > pud_clear(pudp); Agree with Ryan about keeping pmd_present() to be consistent. Reviewed-by: Anshuman Khandual