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t=1781524700; bh=nob7Ef0LhlOFzeo/NONUfcSw5/BZ0C2rsatl1k+CwG0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=luqAq5Ws195uyaNNIqx+TtXLqYwS693yXltM2TcKwMEPE9xcEJ9gXkebKd6da5RvT aAetj7reft8CUSF4tJAD9LUsRfwVv1o2iMAeKI/D7fY+9cxkdZ8RXhupWE6A+X0sNy 70pSyWH+eg6GmOqPpzWKo59VOZ0tk8aIB7nMONpv10msu/A1w2CjvA7BTKHvlLk6N6 dnfzbUvRsGafRRh5PlQymk0GdV65M+uNECKCD6FD5LatW1RC9OMb1pD8sOcqeir4Tx 8O8slBqcLy7jGqX7aUP7Xe7pJfZyrQqbfh1MxNrMTin+UGI3DGmGdHLxFhBTsdAGKT O/UMy/Lz0NpJw== Message-ID: <2d48ef0d-1110-4a9d-adcb-f701a1ce2cfa@kernel.org> Date: Mon, 15 Jun 2026 13:58:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_vma_mapped: revalidate and do proper check before return device-private pmd To: Wei Yang Cc: Balbir Singh , akpm@linux-foundation.org, ljs@kernel.org, riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, sj@kernel.org, ziy@nvidia.com, linux-mm@kvack.org, Lorenzo Stoakes , stable@vger.kernel.org References: <20260508013728.21285-1-richard.weiyang@gmail.com> <5e9ee072-b927-41e0-ba98-c9fdf11eccbc@nvidia.com> <0aab59b8-71c5-4059-8281-5dd876946528@kernel.org> <20260512143542.izpp3gu4iqxttw3f@master> <113dddc5-27e3-4e9e-a90c-f076a4629f51@kernel.org> <20260612024840.qdw76serbgj67yrv@master> 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-Rspamd-Queue-Id: E16A9180006 X-Stat-Signature: yay1qiannpdgm6a53meaztj5a3znqdpz X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1781524700-503075 X-HE-Meta: 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 v3i/vhEb CYYfkSGBPvJ1Qg9/YapQJ+xBtURDWT7lYVRsOu/uFdjp+/HadkNwcR6G3+3i4z+5/DXnYPdXdrUFY44bSC84yrxJq31L+/98m4E/dylrG7lnqvMcsWeh59xrfqkiOqcD0JCyYqnP38rH3SkFKUACAzBN11wuT1B4aeFmFAF7W0v5/fY8h21RqNhsq31/oia/f2S50DmCG9bO+Ijd3PK7RAI/2IcSMy4uyangTlvE/GTcxIpkqE8GJy2HsE4R8pP+S5vbVZxi8ZQA0YnAboZKA2H3tTdaHWPVTwFJpt1sFCSxd66QShGMn+ktHU/elTp1Kt+TRzerVtlRitSLeBYb4RdOV4SQ3tB0xoGg1iiiDHTnECavQiqJHl1uAfYJUrq/Ktr42 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/12/26 04:48, Wei Yang wrote: > On Tue, May 12, 2026 at 08:55:47PM +0200, David Hildenbrand (Arm) wrote: >> On 5/12/26 16:35, Wei Yang wrote: >>> >>> I tried to compress above logic like this, hope it could look cleaner. >>> >>> if (pmd_trans_huge(pmde) || pmd_is_valid_softleaf(pmde)) { >>> unsigned long pfn; >>> bool is_migration = pmd_is_migration_entry(pmde); >>> bool for_migration = !!(pvmw->flags & PVMW_MIGRATION); >>> >>> if (is_migration != for_migration) >>> return not_found(pvmw); >>> >>> if (pmd_trans_huge(pmde)) >>> pfn = pmd_pfn(pmde); >>> else >>> pfn = softleaf_to_pfn(softleaf_from_pmd(pmde)); >>> >>> if (!check_pmd(pfn, pvmw)) >>> return not_found(pvmw); >>> } else if (!pmd_present(pmde)) { >> >> It's more compact, but not necessarily cleaner. In particular, I detest >> pmd_trans_huge(), we should phase it out. >> >> if (pmd_present(pmde) && !pmd_leaf(pmde)) { >> goto pte_table; >> } else if (pmd_present(pmde) || pmd_is_valid_softleaf(pmde)) >> >> ... >> >> Might work as well. But once we add support for other softleaf types, we'll have >> to touch it again. So I'd rather just list what we actually expect. >> > > Hi, David Hi, > > I may not follow you. Just want to confirm whether you prefer this goes as a > fix first, or you prefer it goes as what you suggested here as a cleanup? I guess we should just do it properly when we're touching the code already. Does that answer your question? Will you send a proper patch? -- Cheers, David