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Tue, 08 Apr 2025 11:17:09 -0700 (PDT) Date: Tue, 8 Apr 2025 14:17:05 -0400 From: Johannes Weiner To: Gregory Price Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, longman@redhat.com, tj@kernel.org, mkoutny@suse.com, akpm@linux-foundation.org Subject: Re: [RFC PATCH] vmscan,cgroup: apply mems_effective to reclaim Message-ID: <20250408181705.GE816@cmpxchg.org> References: <20250320210919.439964-1-gourry@gourry.net> 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: <20250320210919.439964-1-gourry@gourry.net> On Thu, Mar 20, 2025 at 05:09:19PM -0400, Gregory Price wrote: > @@ -4296,3 +4296,13 @@ void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task) > seq_printf(m, "Mems_allowed_list:\t%*pbl\n", > nodemask_pr_args(&task->mems_allowed)); > } > + > +bool memcg_mems_allowed(struct mem_cgroup *memcg, int nid) This should probably be cgroup_mems_allowed(struct cgroup *, int) and then have a mem_cgroup_mems_allowed(struct mem_cgroup *, int) that does the e_css translation, with the necessary dummy functions to work with all CONFIG combinations. > +{ > + struct cgroup_subsys_state *css; > + struct cpuset *cs; > + > + css = cgroup_get_e_css(memcg->css.cgroup, &cpuset_cgrp_subsys); > + cs = css ? container_of(css, struct cpuset, css) : NULL; > + return cs ? node_isset(nid, cs->effective_mems) : true; You need a css_put() to drop the ref from cgroup_get_e_css(), but otherwise accessing css should be safe this way. AFAICS you need callback_lock to query cs->effective_mems. > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 2b2ab386cab5..04152ea1c03d 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -342,16 +342,22 @@ static void flush_reclaim_state(struct scan_control *sc) > } > } > > -static bool can_demote(int nid, struct scan_control *sc) > +static bool can_demote(int nid, struct scan_control *sc, > + struct mem_cgroup *memcg) > { > + int demotion_nid; > + > if (!numa_demotion_enabled) > return false; > if (sc && sc->no_demotion) > return false; > - if (next_demotion_node(nid) == NUMA_NO_NODE) > + > + demotion_nid = next_demotion_node(nid); > + if (demotion_nid == NUMA_NO_NODE) > return false; > > - return true; > + /* If demotion node isn't in mems_allowed, fall back */ > + return memcg ? memcg_mems_allowed(memcg, demotion_nid) : true; > } > > static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, > @@ -376,7 +382,7 @@ static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, > * > * Can it be reclaimed from this node via demotion? > */ > - return can_demote(nid, sc); > + return can_demote(nid, sc, NULL); This has appropriate memcg context from get_scan_count(), use that. > @@ -2654,7 +2662,7 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, > return true; > > /* Also valuable if anon pages can be demoted: */ > - return can_demote(pgdat->node_id, sc); > + return can_demote(pgdat->node_id, sc, NULL); Make this take an lruvec, then pass lruvec_memcg() to can_demote(). shrink_lruvec() already has the lruvec. kswapd_age_node() has to do the test from inside the memcg loop, since demotion and thus aging now very much depends on each cgroup's policy. > } > > #ifdef CONFIG_LRU_GEN > @@ -2732,7 +2740,7 @@ static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc) > if (!sc->may_swap) > return 0; > > - if (!can_demote(pgdat->node_id, sc) && > + if (!can_demote(pgdat->node_id, sc, NULL) && > mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH) > return 0; MGLRU, so grain of salt, but that memcg looks appropriate for passing. > @@ -4695,7 +4703,7 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap > if (list_empty(&list)) > return scanned; > retry: > - reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false); > + reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false, NULL); This also seems to have appropriate lruvec/memcg context.