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b=P4QQRuVUU7hB5m0OOB3wt2KTXJDUFb+y7pu+q34nSSBNFQqRIVc/ytfsQeIPtEOwG v7p/4+97u7FcKN3raLCGhu+7R+R7KkI+NC98EfJOThfJyPphRpn9o0CILTjH2GdAOS COYDg0OZBR5BtiW/Z41pYM0N9niLFwI4vSZrn2A+X7RJndciE0QWZaHZHHL/xDHIMM Hgt+WmRNGpDvrfC/jTok5VoWpIeUgQDUWenQ7dGP1lt/ppfqM/u3o4bolao+2aylna SIGrJmBsSFcxIcIweY0EdWpS/ms2JbXjm8WOO8kqdzzCAJYJEQ1qoR0Xo/pg+gvs8m pEMQV7ipJTDRA== Message-ID: <56665ebc-a8de-4d59-a4bc-94b42a6b74cf@kernel.org> Date: Tue, 7 Jul 2026 15:03:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE To: Kefeng Wang , Andrew Morton Cc: Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , linux-mm@kvack.org References: <20260706111958.3649651-1-wangkefeng.wang@huawei.com> <892b2a73-4dbd-4090-89c5-46929530b855@kernel.org> <9beedaa7-0896-4aa2-810e-26042476e7a7@huawei.com> <2e749bbc-86d1-4a10-9809-4777bb5061e7@kernel.org> <5a097591-5a6a-44f2-b440-44a2395fa788@huawei.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C74C9C0005 X-Stat-Signature: 7nnx4b4xjh1my8wtnc7pyjs6bfhxpkp4 X-HE-Tag: 1783429430-283762 X-HE-Meta: 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 4xA6iaNr SfJkDGjYRf7fu5BQjtOE4MMGQk0rO5c+Ely1+3tumfWxusW248vd86rU7+UMIacdfos2iKV4KCgc6vnrrcnZaXPXT4SRWEsLutUtQvvpYPYi7uXfSVeiLDDzS++tldSN4FNfnCZWJScM4Tfm6WmVnJl24axYqoql7nXlwOxqXkXMzDMJzf43HsuKeD23HxqAOr2rAEFJ7RjWzv+yD+4O1cjjTMEzZRtHmT8L34E+g22cCVq+MKDvspb8jfmznS5IZLKPAj7M1cbZO7xyXZIWBgs0Jabp4IpNuj4C0t6MUzxbQaps7ZSrmkmMKS5cKVMhmQkK2nrrQQ+OBOjPkgo2O1WiDztCb1fNfNfieXCfaGGL5/5qMfmDbNOMCAOcK34DtPzJTuho0dIy/ph4mqOc6NTAuQA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/7/26 11:33, Kefeng Wang wrote: > > > On 7/7/2026 3:04 PM, David Hildenbrand (Arm) wrote: >> On 7/7/26 03:28, Kefeng Wang wrote: >>> >>> >>> >>> Yes，device-private entries. >>> >>> >>> I couldn't find a more suitable commit, before a3589e1d5fe3, the >>> flush_cache_page() only called under anon_exclusive, not a device >>> private entry, so there is no issue. This is the reason why I chose >>> this commit. >> >> What makes you believe device-private entries wouldn't have PAE set? >> >> This likely goes back to initial support for device-private. >> > > We only need to make sure that flush_cache_page(..,pte_pfn(pte)) won't > be called under no-present pte, I go back and find the > flush_cache_page function was first introduced to > migrate_vma_collect_pmd in commit 6c287605fd56, so maybe this commit is > better for fix tag? what's your option? That looks about right. For device-private we wouldn't need the ptep_clear_flush (ptep_get_and_clear would be sufficient), but that's a different optimization. -- Cheers, David