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Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0X6ygMa9_1783941063 cluster:ay36) by smtp.aliyun-inc.com; Mon, 13 Jul 2026 19:11:32 +0800 From: "Huang, Ying" To: Gregory Price 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 In-Reply-To: (Gregory Price's message of "Thu, 9 Jul 2026 13:32:18 -0400") References: <20260701222112.2820098-1-gourry@gourry.net> <87echco1w6.fsf@DESKTOP-5N7EMDA> Date: Mon, 13 Jul 2026 19:11:02 +0800 Message-ID: <874ii36t6h.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1703F40005 X-Stat-Signature: 1wbe4aefmgw8wmusqxyes1x7w576kqcp X-HE-Tag: 1783941097-199926 X-HE-Meta: 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 ds8MC6eQ X1kVfJttIE8VAJToXnRKhTQQlLwVARW/DE4U5olS14AoLUZQTysNNjMnnOWiz+WZMLpfdLtgMVk7yznrwJXa8EHMoq7N2afNlORqrolcMpdPkE0EEQmRtIr8wOUbunnXVdGQ56nbDsVNV9aNaaMdpBCl90lrxiwl9ssppkyVWAIbEd9U8jrUvr93bzRhhh6317Trk7gi2FBD+dK1v2jjSaarfEdK8FdwG4gyvPHd9sKlCHcpTT3EjmjOyoxWAMcVeKMUTZqOnL/YrWuoGYsoF1b6Nd8C8i60dBMT1A3Rfjx3JtM6K1wqaroQjOoo5AiKyqM9A0m/xFKD6leMA4jJ7jTpR2jAKlmJPvTobZe/rrhFq+0kQVeZV5BXPkba5Ycb0TsBjSdSkd505WE2WzmJKQs7iHw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Gregory Price writes: > 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. Per my understanding, kernel configured CXL memory can be in ZONE_NORMAL and BIOS-configured one can be in ZONE_MOVABLE. Right? > 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). Anyway, some number will be good IMHO. > 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. --- Best Regards, Huang, Ying