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From: Muchun Song In-Reply-To: <20230612151545.3317766-1-ryan.roberts@arm.com> Date: Tue, 13 Jun 2023 10:16:26 +0800 Cc: Andrew Morton , SeongJae Park , "Matthew Wilcox (Oracle)" , "Kirill A. Shutemov" , Mike Rapoport , Yu Zhao , Jason Gunthorpe , David Airlie , Daniel Vetter , Dimitri Sivanich , Alex Williamson , Oleksandr Tyshchenko , Alexander Viro , Christian Brauner , Mike Kravetz , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , =?utf-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Naoya Horiguchi , Miaohe Lin , Pasha Tatashin , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , linux-kernel@vger.kernel.org, Linux Memory Management List , damon@lists.linux.dev Content-Transfer-Encoding: quoted-printable Message-Id: <3ECE40AA-536E-4A2C-82BA-FE74AA6FB689@linux.dev> References: <20230612151545.3317766-1-ryan.roberts@arm.com> To: Ryan Roberts X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: A0F49180004 X-Rspam-User: X-Stat-Signature: zsiu6gcu3ytqttoxigef8b69xgac3nhh X-Rspamd-Server: rspam01 X-HE-Tag: 1686622637-79648 X-HE-Meta: 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 fsyP5Vda lVNQ0KJXFlEE2TNWo3cyW9QmIs+wUHpElXFfNLEFCkh2ix6LIfU2Q4TFn7o4YYTrod4IjPfsHQUkNrngfBLBJkXD0oWK/i3mugb8w4ILz5+2VAw+aRfFUFBcFIb5tblrNb7vpUdVtYSoCyBnsR/omH0Stc1rPtVUxnm9FCUIvgXvEqyyRDSBI+XhEsRtmER5NsUhdZDqd6LFb/AUMKpuXxDgTHyytnRDH1ZxFjLcuCAFD7zcrjemSqTr+01IdLMFjYkYWk/3fI4ubq0M7udoobPWixWGRgc+ep3RdATwm7gEseueontzBTCUnfkpm0FpUfMVqSmbi8SGToTWOYFd4koD96Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Jun 12, 2023, at 23:15, Ryan Roberts wrote: >=20 > Hi All, >=20 > (Including wider audience this time since changes touch a fair few = subsystems) >=20 > This is the second half of v3 of a series to improve the encapsulation = of pte > entries by disallowing non-arch code from directly dereferencing pte_t = pointers. > Based on earlier feedback, I split the series in 2; the first part, = fixes for > existing bugs, was already posted at [3] and merged into mm-stable. = This second > part contains the conversion from direct dereferences to instead use > ptep_get()/ptep_get_lockless(). >=20 > See the v1 cover letter at [1] for rationale for this work. >=20 > Based on feedback at v2, I've removed the new ptep_deref() helper I = originally > added, and am now using the existing ptep_get() and = ptep_get_lockless() helpers. When I first saw the name of ptep_get()/ptep_get_lockless(), I thought the pte seems like to be protected by the refcount mechanism (Why I have this though? Because Qi Zheng has proposed a approach to free pte page = tables by using the refcount mechanism [1]). And your proposed name of = ptep_deref() is intuitive for me, so I have another thought, should we rename = ptep_get() to ptep_deref()? Just a thought from me, I'd like to hear if others = object. Thanks. [1] = https://lore.kernel.org/lkml/20211110105428.32458-7-zhengqi.arch@bytedance= .com/=