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[109.81.21.195]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-486f5e162d7sm10843415e9.33.2026.03.18.03.01.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 03:01:34 -0700 (PDT) Date: Wed, 18 Mar 2026 11:01:30 +0100 From: Michal Hocko To: Daniil Tatianin Cc: Andrew Morton , Johannes Weiner , Roman Gushchin , Shakeel Butt , Muchun Song , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Axel Rasmussen , Yuanchu Xie , Wei Xu , Brendan Jackman , Zi Yan , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yc-core@yandex-team.ru Subject: Re: [PATCH] mm: add memory.compact_unevictable_allowed cgroup attribute Message-ID: References: <20260317100058.2316997-1-d-tatianin@yandex-team.ru> <20260317121736.f73a828de2a989d1a07efea1@linux-foundation.org> <3db237d0-1ee8-44b7-a356-f3015173f7c2@yandex-team.ru> <7ca9876c-f3fa-441c-9a21-ae0ee5523318@yandex-team.ru> <73322279-c6f8-4319-827b-938c20c96b9b@yandex-team.ru> 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: <73322279-c6f8-4319-827b-938c20c96b9b@yandex-team.ru> On Wed 18-03-26 12:25:17, Daniil Tatianin wrote: > > On 3/18/26 12:20 PM, Michal Hocko wrote: [...] > > Shouldn't those use mlock? > > Absolutely, mlock is required to mark a folio as unevictable. Note that > unevictable folios are still > perfectly eligible for compaction. This new property makes it so a cgroup > can say whether its > unevictable pages should be compacted (same as the global > compact_unevictable_allowed sysctl). If the mlock is already used then why do we need a per memcg control as well? Do we have different classes of mlocked pages some with acceptable compaction while others without? -- Michal Hocko SUSE Labs