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Ehrhardt" , dri-devel@lists.freedesktop.org, Steven Price , Liviu Dudau , Andrew Morton , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/panthor: Check VMA boundaries for PMD mappings Message-ID: <20260623224421.56dba65d@fedora-2.home> In-Reply-To: <20260623220341.7ad4a0e2@fedora-2.home> References: <20260623181942.1536598-1-lk@c--e.de> <20260623220341.7ad4a0e2@fedora-2.home> Organization: Collabora X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: htxk59w15pk3g6xj9cwz89xksrnbjoza X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6DEB2180002 X-HE-Tag: 1782247486-752096 X-HE-Meta: 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 kDvQKcRI 5mAQ1dGm+FWxaXA2fL/os9BYAhpV3FJ6TyQcYjRZPanBWOYooDYcVo0obdUln9K37BCPio0AcSnNzAtST4J5MbXrr7RtggOlD31H9kmeOnP30CqrEGTMc29yje/X/EWfN/NSaiUQvYdhK8+lRpN8OoY7gDA2dooSmMBqEkfC1Up40+8SkBREra36U+u/2MOl7W63wDsZIPPVRZziKwOEIiUUGX0o1NOWKw9hOmZM9f+SQcf9Z3n+T++tGm6gr3/v30PGJYeN3AvViQKMA7jyeeVEJGSUac9rE0mClyOZ60OKtLt3pIL4zY//QHQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 23 Jun 2026 22:03:41 +0200 Boris Brezillon wrote: > Anyway, I'll try to get back to this map_pages() implementation, and > see how we can handle the fallback when locks can't be acquired in that > path (I assume this would mean no PMD mapping in the fallback path if > we get rid of huge_fault()). More on that. I had a brief look at map_pages()/fault_around(), and it seems it's only meant to populate PTE entries, not PMDs. Part of the perf boost we were looking for when adding huge_fault() was limiting the number of faults when adjacent pages are touched, but the other part was limiting the page table depth to optimize page-table walks, so if we're implementing map_pages() without huge_fault(), we basically lose the second part of the optimization. I'd need to check how much perf we leave on the table with that.