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b=UY86iIMcGikyN9u59oMpD3SPoWCDezq083xPacS+VXEBGVM0Lf5REGc9Geud0VJMd wz5dPm+uXnDuXxLBZCE0sM5/ks5eENPD8c0ki6Ad0H1BjivPl3la7dVLMD28shem8B 9YyqNliA6iyYU3qZQsPzqxosOKnQuKz37S1O24AHoy8rl2UKjdLWMC8LlI6RiAnkmy nMmpe3XTaxZ0ql3iyP+uJIqh8J/aWVdijHVSnn9tMTcMeseOc9cYfvoxbusgwfN5TT FHSpcMGeULWL/66IrJQHtK4bgI9OOAKqSECrKDsm+XCANmsF35O697XETEu6ZhRhAt TTzrHtzvna0Yg== Date: Mon, 1 Jun 2026 10:36:33 +0100 From: Lorenzo Stoakes To: Alexander Gordeev Cc: "Oscar Salvador (SUSE)" , 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> <07baafe4-7d1c-42b0-9103-3e5666770061-agordeev@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <07baafe4-7d1c-42b0-9103-3e5666770061-agordeev@linux.ibm.com> X-Stat-Signature: 9xuwkrj78o8ytsa71bjccjxfnwet4zzu X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 81D9F140005 X-HE-Tag: 1780306599-178765 X-HE-Meta: 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 UHRlIJD+ +FjVrTW/CdqWSOHO2xZO1u/BiuJc2meAuypRaRGui1iKcmsezIz1tEUDgU2i1Y9RHjBPSlWQvH1kQA0C9lc+GQ/qeH7vKM/6eY4zy3x5gk9v26eS2Stki3dd5kWN4y1LoH5MIHLTQDfQm3XgfUWMxwHA/qgA8bdY2RrV933KAfex5rsfWaVtZDO63DYOK242ptf4tHx7SGbkxJM5HMiNbNg5m5RXl+1naF/Bw+36wvNSCsQ/iCnhxvjJwdlIvOTn9if/+n5BMOcpkGdJYFtnriKeR/ZxQUjSYvZ6GHAUQRF6Zn/s/RsbLs8ljtKXFfh43SMKVT34ZUBrLKO9QBYaxeXQT99H5AZrWguH3Efgv8Jif2eVYP3dr0h44Kw== 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 04:30:36PM +0200, Alexander Gordeev wrote: > On Thu, May 28, 2026 at 04:14:03PM +0200, Oscar Salvador (SUSE) wrote: > > 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." > > I would gladly use this, if it makes sense for everyone. > > @Lorenzo? Sounds good to me! Thanks > > > Only arm64 makes use of it though, due to the contpte stuff and being > > unable to do it atomically. > > Thanks! > > > -- > > Oscar Salvador > > SUSE Labs Cheers, Lorenzo