From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BC00DC43458 for ; Mon, 29 Jun 2026 07:26:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 798246B0005; Mon, 29 Jun 2026 03:26:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7225D6B0088; Mon, 29 Jun 2026 03:26:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E9936B008A; Mon, 29 Jun 2026 03:26:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 18EBB6B0005 for ; Mon, 29 Jun 2026 03:26:08 -0400 (EDT) Received: from smtpin13.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 76D09405C1 for ; Mon, 29 Jun 2026 07:26:07 +0000 (UTC) X-FDA: 84932116374.13.ECE6D4A Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf14.hostedemail.com (Postfix) with ESMTP id C4A8210000A for ; Mon, 29 Jun 2026 07:26:05 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782717965; b=7G2T57yFQCiH1BzTbJuLw8vCpM/EGBYRqORoBA4Nlsudz+gtKCh0S4y9GHjcT95jxEZION QNVapNXmFJiCWqBwSM8HIBEUBRvFZoPptBQz6YvekvdmWKhEJyjMh7Z+TbV2u5SB/huirK JpVmPfIP4hBtf0B9FCIY5edhPvnENXk= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782717965; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0t5WKgX7491nnO1TWw1NvgfhMDEnzDCwVnx65iBvCrk=; b=2H7OTolCgwEJMWcLQljnUa1AaZ3yJtkbcxiYkjXOnd+Vv9uhBCI29zeRPX+e8pcbVWy4nG ID7dz/lN8VE4A3b9yRntJV96Ax6DDJiMtm+hLl+ta8Uv/iy6H/skqxdMabNQG1pWlCL0FC yq86rH3cwAntGZfHOxcvwreL8UUDuIE= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 169F860052; Mon, 29 Jun 2026 07:26:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 952701F000E9; Mon, 29 Jun 2026 07:25:53 +0000 (UTC) Message-ID: <0fabee2a-edb7-41c8-91ec-8cf0646c9e83@kernel.org> Date: Mon, 29 Jun 2026 09:25:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/5] mm/page_vma_mapped: use huge_ptep_get() for hugetlb To: Dev Jain , Lance Yang 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> <98f3aedd-de11-4a83-81b8-f3e3c9380e49@kernel.org> <1d6d699e-62e5-424f-a147-b7a75b966957@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 X-Rspam-User: X-Stat-Signature: 5mecfscq8fs13b55h5ygacm4wtw9mpm8 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: C4A8210000A X-HE-Tag: 1782717965-195290 X-HE-Meta: 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 duriKRZs IuXGBFvfI2onOiKClbnSXjIRqgR3KRcqhoFgc+qym4ee4uqLmr4BmkfsNgCL3NFY6bav9wXPMvmBcWJxZev6aM1hH85k0GJ2M4YOXWErwTiw1J08ylfzCx0MCEeUbKq0JT28g8kA8U5Cl7+lQbbKwyXvrApy5IGr8rvBWoqx28sz2H6730YDLNeG6HU36CxKU/+ui9y+OlTQmxM9nW/u1Y2bQxa4EkNPp8/kOSROPhpwwLewJAPRFHIln+ntAh2Fdm/6SyXuR/Ezfpq9FW7uZDV7oeWNH5MGs9R74SNcStnrPATWdyioV6D1YWpO+FaOqzCwpHQx1szTECXDQ9/VL9+nfBgl/7ylGQwLk0q0wvrUmJjMXA2FPu1stY/zZYvhylKg5g+hpPn25JHA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/29/26 08:48, Dev Jain wrote: > > > On 29/06/26 12:09 pm, David Hildenbrand (Arm) wrote: >> On 6/28/26 07:44, Lance Yang wrote: >>> >>> [...] >>> >>> Yes, that's what I had in mind :) thanks! >>> >>> >>> 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. > > Sashiko notes other places: > > https://sashiko.dev/#/patchset/20260625112955.3254283-1-dev.jain%40arm.com Yeah, that looks shaky. We do seem to have a bunch of these cases, primarily from pagewalk code (where some users like pagemap need the actual address). I think we have two options 1) To prevent any (further) issues, make huge_ptep_get() always consume the hstate, and let the arch code deal with aligning it. Invasive. 2) Make the arch code handle aligning without the hstate. diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 30772a909aea3..303a1b74796c9 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -126,6 +126,9 @@ pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep) return orig_pte; ncontig = find_num_contig(mm, addr, ptep, &pgsize); + ptep = PTR_ALIGN_DOWN(ptep, sizeof(*ptep) * ncontig); + orig_pte = __ptep_get(ptep); + for (i = 0; i < ncontig; i++, ptep++) { pte_t pte = __ptep_get(ptep); (nshift/order instead of ncontig might avoid a multiplication, but not sure if that matters in practice) IIUC, that's similar to what huge_ptep_get() does on ppc. static inline pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { if (ptep_is_8m_pmdp(mm, addr, ptep)) ptep = pte_offset_kernel((pmd_t *)ptep, ALIGN_DOWN(addr, SZ_8M)); return ptep_get(ptep); } I'd assume we could do the same on riscv. Besides that, I don't think any arch has cont entries. Interestingly, huge_pte_clear() / huge_ptep_get_and_clear() and friends would be all wrong when the wrong address is passed. But that code really is called from hugetlb.c where we should take better care of that. (e.g., partially zapping a hugetlb page is not possible) -- Cheers, David