From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8581D2BD022; Sun, 5 Jul 2026 07:36:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783236962; cv=none; b=XBzpx2aT31ymhcEajT2k4HDb9uivF/QNnrXzYsm9y7WYJKv7B2mTeFBdsIgVPzh/u3aZfp5/xKCj9/bN5riwpIAajywifXnZUHcFZ5DHvC7GdP1VIoAvVAPOT4HYk/0mj4jfVbH8mzdXpWqajpPNFkki1HCgZ2H12dURlX7l/xk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783236962; c=relaxed/simple; bh=dhV3rAHYOOY40GMAAV1Oa9f7E0UcCzryZIJUH5O1KNw=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=hdIuNdTuq3Hg7YhViGci3RWldNrErwdmeoz0VchjUnbwn3lTzihLEeE7ur8eCujwjgiXaLvBRF2QZ+xWijv6WhvomhOwYUGWsrqtW5cJa2Pa5KF/tJ7nfRta9seEIbvHMMBqzd9vv8FNMY0KJuZgq1xroZ6kS+zI59WBIM2r0lQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=FWr7oYXO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="FWr7oYXO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E68261F000E9; Sun, 5 Jul 2026 07:35:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783236961; bh=A6ZkehhfOr5XXJ3jery3AcqU6u9rwntx9neKtZ84pmI=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=FWr7oYXOt5Tp+K6Ek8q6APpXSMD+p/aNq4SvRIWBniP6sobBE8u2g/45GuabtZ7Lh 5E6jKvT6FbQ902LJvZk8l9k4niP2mOqpY3EAy0PXbjEdEmkzyqGxqmXJfvqHOtrnHp 7W8TPuCgfYN9bK/6++23sY3tVDsVYxqEXnEpRnKA= Date: Sun, 5 Jul 2026 00:35:59 -0700 From: Andrew Morton To: Dev Jain Cc: muchun.song@linux.dev, osalvador@suse.de, ljs@kernel.org, david@kernel.org, liam@infradead.org, riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, apopple@nvidia.com, rcampbell@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, ak@linux.intel.com, nao.horiguchi@gmail.com, mel@csn.ul.ie, j-nomura@ce.jp.nec.com, pfalcato@suse.de, tglx@kernel.org, dave.hansen@intel.com, jpoimboe@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: Re: [PATCH v3 1/6] arm64: make huge_ptep_get handled unaligned addresses Message-Id: <20260705003559.8b124d2b94b685cc2e4e77ae@linux-foundation.org> In-Reply-To: <20260703114202.365553-2-dev.jain@arm.com> References: <20260703114202.365553-1-dev.jain@arm.com> <20260703114202.365553-2-dev.jain@arm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 3 Jul 2026 11:41:54 +0000 Dev Jain wrote: > huge_ptep_get() can be handed a virtual address pointing to the middle of > a contpmd/contpte mapped hugetlb folio (examples of callers are > pagemap_hugetlb_range, page_mapped_in_vma). > > The arm64 helper rewalks the pgtables in find_num_contig to answer whether > the huge pte we have maps a contpmd or a contpte hugetlb folio, and > returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over the > contiguous ptes. We can falsely return CONT_PTES instead of CONT_PMDS > if the addr is not aligned. > > Fix this by aligning the pmdp pointer down to a contpmd base before > checking equality with the passed huge pte pointer, to correctly answer > whether the huge pte is the base of a contpmd block. > > Fixes: 29cb80519689 ("arm64: hugetlb: Cleanup huge_pte size discovery mechanisms") > Cc: stable@vger.kernel.org Please describe the userspace-visible effects of bugs when fixing them. Particularly when cc:stable is proposed. Thanks.