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 0F3FF39A04B; Mon, 29 Jun 2026 06:39:32 +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=1782715173; cv=none; b=UwrsMu5ey/yF2p54pkNPADOUV35Zc+VgbhPRnz/xpqISIkM1y8I52xomt94KRiJqYFtduJg2v9zQvFQ6RvafiCwAJEd+lOnssMDGFYGBmAHDUvr6cz/rM144UqRGFqt4wbKYQKcOZGYupCIGaFgjnbJOYtdVmGjSE3Q9QiQWnaE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782715173; c=relaxed/simple; bh=OTdvRc7Moe2MK5GCd0BNtuJZNhCICNZ8x3XPuOdVas8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SUttzBOKVOtg0neomveLUdk3nNRpyBL/4rqmaf6Ige7Q44kwWahJako6+6a/Rt4G8CIh36RQIbRZSXOyZk1RPk+AWJCYykinU7qsLGj8A9/9CXu+g4XggeEy83oQnd22Xm+Wg5eM7ADtZGvVirkKCgzzhfQgWmxZ2wKgC9NWlUI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=R3k9YUwH; 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="R3k9YUwH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 023571F000E9; Mon, 29 Jun 2026 06:39:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782715171; bh=cQw1a/kEB3mNmeLx7vc6yl8U+kM7fc1WO7NLhI45kwo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=R3k9YUwHvqJr6hD5xfkx9NumEmjX/ilAxlkpJG1EZuq6alPxC5Y9iZKiztOuO4ZgQ KPTxcb0fnk4uvqc7kShBOFHJhIHT/H/PDyoUn1nQ9cQlaXtnenyJEdQrmYVXHlTY7c 0MTnR9v6SajCC4vyDUw4TTkZUVIabyhlvg1njEulBEvfAD43hvmqvBa9uXtu/jx+cz EP4CoCIVcWDTNEH85CmoXAoxoU/GFlSAv77Ou2u3u7mYSGdATE5wuxfTbLNXhBqQVl PL8tAsTqKpriFyHM89UR4f6pbPL4F7+hd97SAL/RqTCS9Ui+Idf8ILiZYg4gUZviYE niz6wrb/7SBvg== Message-ID: <98f3aedd-de11-4a83-81b8-f3e3c9380e49@kernel.org> Date: Mon, 29 Jun 2026 08:39:22 +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 4/5] mm/page_vma_mapped: use huge_ptep_get() for hugetlb To: Lance Yang , dev.jain@arm.com Cc: linmiaohe@huawei.com, muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@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, mel@csn.ul.ie, nao.horiguchi@gmail.com, ak@linux.intel.com, j-nomura@ce.jp.nec.com, pfalcato@suse.de, dave.hansen@intel.com, tglx@kernel.org, jpoimboe@kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org References: <82395f5a-31d4-406b-b7ec-10d1a9d067d4@arm.com> <20260628054402.76978-1-lance.yang@linux.dev> 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 6/28/26 07:44, Lance Yang wrote: > > On Sat, Jun 27, 2026 at 12:43:31PM +0530, Dev Jain wrote: >> >> >> On 26/06/26 10:16 pm, Lance Yang wrote: > [...] >>> >>> Just thinking out loud: given that huge_ptep_get() already assumes that >>> addr matches the huge pte, at least on arm64, would it make sense to >>> have a small hugetlb wrapper around it that takes hstate and aligns >>> the address before calling the arch helper? >>> >>> Might make the rule clearer, and a bit harder to get wrong again :) >> >> Are you suggesting something like: > > Yes, that's what I had in mind :) thanks! > >> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h >> index fdb7bdf7645c..xxxxxxxxxxxx 100644 >> --- a/include/linux/hugetlb.h >> +++ b/include/linux/hugetlb.h >> @@ -825,6 +825,15 @@ static inline struct folio *filemap_lock_hugetlb_folio(struct hstate *h, >> >> #include > > Maybe worth spelling out the rule as well: > > For arch helpers that use addr, huge_ptep_get() assumes addr is the > address for the hugetlb entry ptep points to. arm64 already makes that > assumption. > > Callers where addr may not be hugepage-aligned should use > hugetlb_ptep_get() instead. Do we have any examples where code would do that? I would think that all code must properly align addr ahead of times. -- Cheers, David