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Thu, 30 Nov 2023 13:46:33 -0800 (PST) Received: from dschatzberg-fedora-PF3DHTBV ([2620:10d:c091:500::7:5fb0]) by smtp.gmail.com with ESMTPSA id vy13-20020a05620a490d00b0077da601f06csm865412qkn.10.2023.11.30.13.46.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 13:46:32 -0800 (PST) Date: Thu, 30 Nov 2023 16:46:30 -0500 From: Dan Schatzberg To: Andrew Morton Cc: Johannes Weiner , Roman Gushchin , Yosry Ahmed , Huan Yang , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Shakeel Butt , Muchun Song , David Hildenbrand , Matthew Wilcox , Huang Ying , Kefeng Wang , Peter Xu , "Vishal Moola (Oracle)" , Yue Zhao , Hugh Dickins Subject: Re: [PATCH 1/1] mm: add swapiness= arg to memory.reclaim Message-ID: References: <20231130153658.527556-1-schatzberg.dan@gmail.com> <20231130153658.527556-2-schatzberg.dan@gmail.com> <20231130133340.36140526608289898acb3ac5@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231130133340.36140526608289898acb3ac5@linux-foundation.org> X-Stat-Signature: ngkm1p6fojb15hdqf5swkjq3xe8gz3kb X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2B1228000E X-Rspam-User: X-HE-Tag: 1701380793-177632 X-HE-Meta: U2FsdGVkX1/pdF517Nz8PeWlYTouOu/AODUjkjmYOpfsB3A8WQDVRP57eYZSCwZSGidyyoFosE+wRZb/4w0zQTcRMQhZOxnZNrEsUbQNgkF3lJYt4BqPsXK6XAS6TA6ctt+HsC3+Gwz+NccisdXuKRXX9Yb025zqAipCr4PkovONfao1VmST8ORelYkWzb3yCS3s8kZbuEqsJSUVfzU1FbYUbPysO2CAVpIOxd3knB1l5GCVkjAK3PsBAvWxGgCYY1gAP65JKpo4k2vwIPmExaCn8MqNrQTm3933srYFzHqzZ0dJ1NCAQVA5ZvcLKPRSF5rqUafBxsHc8jTuwdz/MUBf3+kEMK2jAaInPhSSuRgYu9mqsDyA0BwsUUiqK8fLNxVEYfArGzUh6MsYiWkPp+8+tgyRyNtVRGP212v4Gh3WfDv3MlEk7q3rfxb5aX/TFHqGX3Ptl5ykKuhmhNpYKzTDvVC1Eqj/eJyA8jxYjNobnCWH8LUlznV5jHPKJ5v9kqphOcTyvFaPsFddsCWDF7JGO7FzCZivFwKWms1d07KyEV2z1omyrH6yzvayeHQpNeWTKgrs3xPVOJXr/VtZ1IUe+RdKGlkGB389MBF8KFeJHEhUA7kvyH+UiIpDl34tFpQssGKlZs304b2v29+zNpPkHgdEdxxWuV6KxqXOgXF9DxpmC0P/GhJoTf/etyaH7LxTWD4khQ0Ub19uixzoSi94p7oQK+Ja14A3A06w3MumfYJ4drXz4u5ukGQveur9HJOs6xXOa/uKZqKHr4L9LdCHAK9k4umNQEUeyvnVMHc5pS9/QDFMi34LSbrjQpNdEAvPvcZn6RIYRxrBYGn6qe/l6Abk+/dyWBNUxTvNmI4Uf4T/PFoYp8W2ETP7hY+mqRCNJXVzyVAHjlcHT6WyfMB5O7P7JdUjbsvw6tQyA83fkngirP0doNKGG6XeMLGAiN0RvXe2iMQ3PwQgWUr TraPSSEs 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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 Thu, Nov 30, 2023 at 01:33:40PM -0800, Andrew Morton wrote: > On Thu, 30 Nov 2023 07:36:54 -0800 Dan Schatzberg wrote: > > > Allow proactive reclaimers to submit an additional swappiness= > > argument to memory.reclaim. This overrides the global or per-memcg > > swappiness setting for that reclaim attempt. > > > > For example: > > > > echo "2M swappiness=0" > /sys/fs/cgroup/memory.reclaim > > > > will perform reclaim on the rootcg with a swappiness setting of 0 (no > > swap) regardless of the vm.swappiness sysctl setting. > > > > Signed-off-by: Dan Schatzberg > > --- > > include/linux/swap.h | 3 ++- > > mm/memcontrol.c | 55 +++++++++++++++++++++++++++++++++++--------- > > mm/vmscan.c | 13 +++++++++-- > > Documentation/admin-guide/cgroup-v2.rst is feeling unloved! Oops - total oversight on my part. I'll add docs in a V2 if we can come to consensus on this interface change in general. > > Please check whether this interface change can lead to > non-backward-compatible userspace. If someone's script does the above > echo command, will it break on older kernels? If so, does it matter? Older kernels will return -EINVAL with such a command - that seems appropriate, indicating that the argument is not supported.