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b=UwXIR2ne7qIEdQieKjg2fk0ArW6TCOdBh6pDCicZUiTQMTn8zUfuwKpyzz79+ZAOc J5LNaa8pycGGpXjpb8vmu9SrBxYpeJVvQwETKbMlVpou2QDvaG0pr+52oOBCA3Uj1q aIBysXOesDEjZp/tW2gzNZtRskQpwGH/pcvII8QIOwcRLKo8BaXtvod3NtgOwEtNhf YoD7cKL98m7iqwH1GgvEE40WcgNZKFFY+azFmtztq27kw0BKnop75mmhEtMoJOz1s6 YxDUIacv9uC2uD0qaU3PIPNQdB8pQNn9XiDnmgKhhhUrteIEnctGScyokHsN/HkZ+3 AhqvdH+EN9bBQ== Date: Thu, 28 May 2026 16:14:03 +0200 From: "Oscar Salvador (SUSE)" To: Lorenzo Stoakes Cc: Alexander Gordeev , Andrew Morton , David Hildenbrand , Anshuman Khandual , Oscar Salvador , Wei Yang , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm/page_vma_mapped_walk: Use ptep_get_lockless() for lockless access Message-ID: References: <20260528075507.1821939-1-agordeev@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: sf14ai3rk4d7j5z45ms6chpz1rbdsi46 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 0C915100016 X-Rspam-User: X-HE-Tag: 1779977649-202249 X-HE-Meta: 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 S8v9R8P6 kq78Iy7MJl0M5/Ymb+IbHrCkPiIwhdRw2G1qVu6WpLJ0AWLUUa855jC/cPMPOh/qUutGsXOdFRFEVewyp2xJZwyPhZF/IHdBjDGiTAg+YkKX2vXhhSfn1PslabH/jK4Mx32tp0IqiGeUPuIpP9ZYCobzYafl13R+SCgYRfGy6bYBIP8UBnPWmBJspr0oo83UlR2fNCtFpFQs8nFdieaHzUlBhP53jBes5Lxqk4qtf0K5f8bcTBUo/dTK29pjG/EIcKZ6MozbWTHAJONNYTjlCTy4oM8HzJhXN9mwF21VZ11gg/ntUMpp2VR8QeyzYsLsBd2SjzCJkkiI+dvU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, May 28, 2026 at 12:24:35PM +0100, Lorenzo Stoakes wrote: > On Thu, May 28, 2026 at 09:55:07AM +0200, Alexander Gordeev wrote: > > Switch from ptep_get() to ptep_get_lockless() accessor for > > PTE reads when no lock is taken. > > This is an insufficient commit message that's just saying what you're doing, > which isn't very useful. > > Please explain why you're doing this and what the benefit is please. Maybe something like "When not holding the lock, there is a chance that the pte gets modified under our feet, so we need to use the lockless API to make sure that the entries remain consistent during the read." Only arm64 makes use of it though, due to the contpte stuff and being unable to do it atomically. -- Oscar Salvador SUSE Labs