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[142.167.219.86]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6eec965a18dsm63016516d6.55.2025.04.01.08.19.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Apr 2025 08:19:51 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1tzdP5-00000001Lxl-1sHc; Tue, 01 Apr 2025 12:19:51 -0300 Date: Tue, 1 Apr 2025 12:19:51 -0300 From: Jason Gunthorpe To: Xu Lu Cc: akpm@linux-foundation.org, jhubbard@nvidia.com, kirill.shutemov@linux.intel.com, tjeznach@rivosinc.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, lihangjing@bytedance.com, xieyongji@bytedance.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH RESEND v2 3/4] iommu/riscv: Introduce IOMMU page table lock Message-ID: <20250401151951.GG186258@ziepe.ca> References: <20250318035930.11855-1-luxu.kernel@bytedance.com> <20250318035930.11855-4-luxu.kernel@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250318035930.11855-4-luxu.kernel@bytedance.com> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 888A1A000E X-Stat-Signature: cqzjpq88khuohyfsnzehsnqi6wusopnj X-Rspam-User: X-HE-Tag: 1743520793-195544 X-HE-Meta: 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 6T+xEvU9 3ZHLa/d1OR6BWjgqodt35944yDS7RNvlV4agCCbPA2Rlc959+9jtOVtk2ey6lEbMu2dZxTWhRiUPUjy0b+bUFodaj5GfgydbM1YEsyF6WiFOf2jIbpp8MvxM2svd49nCx9yTlFgkp1tq322ShGRkmCOIrlnz60rxIWI2gWg2exmZB8FleZqdJ1Km/lsrjNpVo/r4vtZDhpoiGZaUFg6sG6CZhXcD5uSw1OY3AeeV0BLzjBhKojZ47y8Z2tMi2vSMxwpoMT8D4tzVAtwuBrHCgCTTSC4g9btV6FJxT 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: List-Subscribe: List-Unsubscribe: On Tue, Mar 18, 2025 at 11:59:29AM +0800, Xu Lu wrote: > Introduce page table lock to address competition issues when modifying > multiple PTEs, for example, when applying Svnapot. We use fine-grained > page table locks to minimize lock contention. This does not seem right, there is no need for locks to manage a cont bit on the iommu side. Jason