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X-CSE-ConnectionGUID: GbNkHOA1RWSACitFKwzCjQ== X-CSE-MsgGUID: atH2hMzYT+OiZg747uwCKw== X-IronPort-AV: E=McAfee;i="6800,10657,11719"; a="85199090" X-IronPort-AV: E=Sophos;i="6.21,324,1763452800"; d="scan'208";a="85199090" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2026 12:06:26 -0800 X-CSE-ConnectionGUID: VUSTvsphSBy/o93IyD6Yfw== X-CSE-MsgGUID: KnN07GWQTbKsjLEmGuH2bw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,324,1763452800"; d="scan'208";a="217680838" Received: from abityuts-desk.ger.corp.intel.com (HELO [10.245.245.170]) ([10.245.245.170]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2026 12:06:22 -0800 Message-ID: <756d0e9d67750f2c7c46baba3763d692d8778f3a.camel@linux.intel.com> Subject: Re: [PATCH v3 1/4] mm/mmu_notifier: Allow two-pass struct mmu_interval_notifiers From: Thomas =?ISO-8859-1?Q?Hellstr=F6m?= To: "David Hildenbrand (Arm)" , intel-xe@lists.freedesktop.org Cc: Jason Gunthorpe , Andrew Morton , Simona Vetter , Dave Airlie , Alistair Popple , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Matthew Brost , Christian =?ISO-8859-1?Q?K=F6nig?= Date: Wed, 04 Mar 2026 21:06:19 +0100 In-Reply-To: <07fb6811-68fe-4cb9-95e5-ded58a082493@kernel.org> References: <20260303133409.11609-1-thomas.hellstrom@linux.intel.com> <20260303133409.11609-2-thomas.hellstrom@linux.intel.com> <07fb6811-68fe-4cb9-95e5-ded58a082493@kernel.org> Organization: Intel Sweden AB, Registration Number: 556189-6027 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) MIME-Version: 1.0 X-Stat-Signature: ywxj9djfpr6u1a67ro87z6bmgktdxcsf X-Rspam-User: X-Rspamd-Queue-Id: 2782FC000A X-Rspamd-Server: rspam12 X-HE-Tag: 1772654788-905956 X-HE-Meta: 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 Nc3NKOzG sjffSX5ovaTNvxF6C8n5UBzNMS1Y+yqj4ukn7GWD31+/gGhaq4j/uuOG/1VLqpYsVMoaJ4uZbMZ7dzMcbUwTIfRKKjN9Um+uZ7LjZLHTV9UGYOpXXRmuxJcHChB4RuAovs7XLyWrNOR+R1KfB3vXrZCBtJmeVLGBmVUizRKs6nn0jK2wzqvy4mYv7Mu+rpuImUVOJLz/tW4ZbM+L6nvsm7hkeh3vmJ2YD5dZumWDEbydwLJGopL0nLUW6WTC3sTSt4sVi Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 2026-03-04 at 20:32 +0100, David Hildenbrand (Arm) wrote: > On 3/3/26 14:34, Thomas Hellstr=C3=B6m wrote: > > GPU use-cases for mmu_interval_notifiers with hmm often involve > > starting a gpu operation and then waiting for it to complete. > > These operations are typically context preemption or TLB flushing. > >=20 > > With single-pass notifiers per GPU this doesn't scale in > > multi-gpu scenarios. In those scenarios we'd want to first start > > preemption- or TLB flushing on all GPUs and as a second pass wait > > for them to complete. > >=20 > > One can do this on per-driver basis multiplexing per-driver > > notifiers but that would mean sharing the notifier "user" lock > > across all GPUs and that doesn't scale well either, so adding > > support > > for multi-pass in the core appears to be the right choice. > >=20 > > Implement two-pass capability in the mmu_interval_notifier. Use a > > linked list for the final passes to minimize the impact for > > use-cases that don't need the multi-pass functionality by avoiding > > a second interval tree walk, and to be able to easily pass data > > between the two passes. >=20 > Please CC all maintainers+reviewers that MAINTAINERS recommends you > to cc. Hmm. Good point. I missed a fair number of those. Will Resend Thanks, Thomas