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 B4CFC40D570; Mon, 6 Jul 2026 08:46:56 +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=1783327623; cv=none; b=JnLDTYaMCzuQh+kcyXGdE7LJTSyPpn6g1OnNV6Hr42rJCk0HnG4Vm9gbRxZ2ft9X+rtU9LqN65+xg6NFg3gZu0fEBNXyqm/WofVJinCfa6w/xF64Iqb+PntXu3uCo4fYUe6VSmn/zuWj5AmtimohJxLag7EKxUHFEWKN36buHWY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783327623; c=relaxed/simple; bh=2YAN5xBNtq5Kr1nbTwMWz0XC96gvZ7I1Hvx388bdRog=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aXRgUvZAIrvXmgbZpg1bK2wFNdmumXmZ3IeGyC8xw4r0js/y5Frb263laALICybYl2gzppyHBjm9QUXiYO0Z6aWn3C+4jXZ1h4U2r7lTqoihOhMJotpyT5WNjt2QmF07IjHucFk/UG88EMwVryhX7L/EEd8NmrQan+TvDA+i8OU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L3DTPkDZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="L3DTPkDZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E63991F000E9; Mon, 6 Jul 2026 08:46:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783327613; bh=aamOsmuHLb37FH1la8uw/6nypO2zKI4knV9R9WdC8zI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=L3DTPkDZIUqx8Nk3kg9DUA6JR3HqOcCsSX4NbFsz4WFSgtNVQMdkoN5a41c62uDHv icaF8G3VgRIoGP6n4uD6rhGTP4oP3JqTLGKokoFQU50Q90ccE8OW7ZBi+a78i6djhh OV5Am7CETroE8xw1t6J4CsHdIuLYlbRsI1YALg2ZU9eL5UaEHal9eJxV5DRfSL/M1h B5nZuUCJFgaqeKICeh80D9+yBsHHLKezZHfHDc/raytvewe6gOcTukVLhi0/qQ5r6p LFQtXgKP47EPzEWteN1rHgtc6PM8M7bgUbfSp+oCHMzp6qPzikCzYqLMDhUe80knPC s4xvfwYyVo7Ew== Message-ID: <2e20d635-6326-48d1-af0b-776b15f47ce8@kernel.org> Date: Mon, 6 Jul 2026 10:46:42 +0200 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 3/6] mm/rmap: use huge_ptep_get() in try_to_migrate_one() To: Dev Jain , muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org Cc: 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 References: <20260703114202.365553-1-dev.jain@arm.com> <20260703114202.365553-4-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/3/26 13:41, Dev Jain wrote: > try_to_migrate_one() is used by folio migration to replace a present > mapping with a migration entry. For hugetlb folios, page_vma_mapped_walk() > returns the pte pointer to the hugetlb folio in pvmw.pte, but the code > reads the huge pte entry with ptep_get(). > > On arches which provide their own huge_ptep_get() to dereference a huge > pte pointer, accessing via ptep_get() would cause pte_pfn(), pte_present() > etc to misbehave. > > It is not clear whether this has a trivially visible effect to userspace. > > Use huge_ptep_get() to dereference a huge pte pointer. > > Commit a98a2f0c8ce1 copied the bug from try_to_unmap_one into > try_to_migrate_one. > > Fixes: a98a2f0c8ce1 ("mm/rmap: split migration into its own function") > Cc: stable@vger.kernel.org > Acked-by: Muchun Song > Signed-off-by: Dev Jain > --- Acked-by: David Hildenbrand (Arm) -- Cheers, David