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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8849f9ae48fsm459499385a.24.2025.10.10.11.53.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Oct 2025 11:53:32 -0700 (PDT) Date: Fri, 10 Oct 2025 14:53:30 -0400 From: Gregory Price To: David Hildenbrand Cc: Michal Hocko , linux-mm@kvack.org, corbet@lwn.net, muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, hannes@cmpxchg.org, laoar.shao@gmail.com, brauner@kernel.org, mclapinski@google.com, joel.granados@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Mel Gorman , Alexandru Moise <00moses.alexander00@gmail.com>, Mike Kravetz , David Rientjes Subject: Re: [PATCH] Revert "mm, hugetlb: remove hugepages_treat_as_movable sysctl" Message-ID: References: <271f9af4-695c-4aa5-9249-2d21ad3db76e@redhat.com> <83e33641-8c42-4341-8e6e-5c75d00f93b9@redhat.com> <1d7476e6-5c6d-4175-b28d-3622222ea8e6@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1d7476e6-5c6d-4175-b28d-3622222ea8e6@redhat.com> X-Rspamd-Server: rspam01 X-Stat-Signature: 1w83ipedr71g576s5nx7aet46848b8xc X-Rspam-User: X-Rspamd-Queue-Id: BF57840010 X-HE-Tag: 1760122414-558118 X-HE-Meta: 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 P88nGMFU 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 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 Fri, Oct 10, 2025 at 09:40:29AM +0200, David Hildenbrand wrote: > > > > Seems like this is pretty stable tbh. Obviously if you hack off the > > node0 hugepages migration fails - but I feel like you're signing up for > > that when you turn the bit on. > > Right, just needs to be documented thoroughly IMHO. > happy to make any doc adjustments. Better to move any notes every here though: https://lore.kernel.org/linux-mm/20251009161515.422292-1-gourry@gourry.net/T/#u --- Maybe worth finding some time at plumbers to discuss block-level allocation twiddly bits. Still not quite clear how this would pan out. Maybe it's as simple as adding GFP flags to blocks and having something like: echo NO_KERNEL > sys/bus/node/devices/node0/memory1234/eligibility echo PINNABLE > sys/bus/node/devices/node0/memory1234/eligibility folio_to_block(folio)->eligible(gfp) The issue here is obviously that it's clearly racey, in that a bit twiddle can change the eligibility mid-allocation. I'll think a bit more about this. ~Gregory