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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-92e90bb91adsm1705974285a.20.2026.07.09.10.32.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2026 10:32:22 -0700 (PDT) Date: Thu, 9 Jul 2026 13:32:18 -0400 From: Gregory Price To: "Huang, Ying" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@meta.com, willy@infradead.org, jack@suse.cz, akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, apopple@nvidia.com, Johannes Weiner Subject: Re: [PATCH 0/2] mm: don't apply task mempolicy to unmovable kernel allocations Message-ID: References: <20260701222112.2820098-1-gourry@gourry.net> <87echco1w6.fsf@DESKTOP-5N7EMDA> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87echco1w6.fsf@DESKTOP-5N7EMDA> On Thu, Jul 09, 2026 at 07:09:29PM +0800, Huang, Ying wrote: > Gregory Price writes: > > > The unmovable unaccounted kernel allocations stop following the > > task policy and place node-local. With no policy set, both place > > node-local as before. > > Personally, I think this should be the right thing to do theoretically. > However, you may need to find some practical issues that this resolves. > I don't entirely disagree, but there is at least one scenario where this is an obvious improvement: BIOS-configured CXL memory brought up in ZONE_NORMAL. An task interleave policy on such a system will end up with unaccounted kernel allocations landing on the remote node, which is just not preferable at all (and uncorrectable). It's not a complete fix (fallbacks can still occur under pressure), but it's one piece of the puzzle. Forward looking: This patch makes private-node's with ZONE_NORMAL reliably hot-un-pluggable. But that improvement is obviously predicated on work that isn't upstream (yet :] ). I need to send a v2 of this with SLAB_ACCOUNT fixed up, and some numbers to justify dropping the pagecache fix. But I will probably sandbag this a bit until i finally send out v5 of private nodes. ~Gregory