From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f44.google.com (mail-oo1-f44.google.com [209.85.161.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E0A8A3A9D87 for ; Fri, 10 Apr 2026 21:07:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775855286; cv=none; b=PnQEH74Zb/Z3ftZSIedusYkcjXRL+js9LkbelooQ68QKKIIqzb6vNcPags9dbRme+KpdSKwbGRYmjk6O7ietJEk2u/Fo4XK/oFcuzXFGNTdon0HtXL14lrdk2kbJoV0Mf/JzLsi1cGTnnxB8k10UAyAy3X+zt7zg1GwOR6KbXqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775855286; c=relaxed/simple; bh=uHZSosdPaz/5klkEV1FY2gO/CN0MqSO80Sx627Bwhzw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sVGL/cM/p5bq/QvMa1xC2uiFhT9U5cEsu/LzbaoZ3FReM3WdyL790nVd6k+/OBc/9TB3tqsTDedt71MZRo6pY4vB56ZZPzZBO5BXpjfncGrKmTZm8ppURSBi7bAYxW2DplzIv99EIuao605nsHYjS8URTGrwft0MgZFvkTyZ40s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ktEoy/Jo; arc=none smtp.client-ip=209.85.161.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ktEoy/Jo" Received: by mail-oo1-f44.google.com with SMTP id 006d021491bc7-679b072ed3aso1157526eaf.1 for ; Fri, 10 Apr 2026 14:07:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1775855277; x=1776460077; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=esfCictnJyPc20j2EkkTX38W+qKv+nRwhZtLvjA9q1E=; b=ktEoy/JoxcModDbVQ1E7R0xZgF68ITdXuS5+HH4cx1Vq6XzHFDvddqAWjdNlyWbLpt 1lbqm53Jgkr9hAyBnyi6QWpWvoZJf3rmRA0h+v4VnpS/g382fAFrcPcJdWNUad21hrCd zrsPiHDPR8srWv45oVRT4BjN7UfIZqMB3w35vtbTjaRP35TIx1lS404/KlfJxXmaDZ8E nST5ajUM34sDgC1KEiBdiIUup6zrh9pBx+fhb/aBKDUm8NyKVtieO0IuBlbQbVfuzF0X pHahyvPb5LlwulG74g10ca8kUuo1rNLwHRvHT8OdjYxjPg7iTTwPnEfROtEIsCS9PWtL wt7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775855277; x=1776460077; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=esfCictnJyPc20j2EkkTX38W+qKv+nRwhZtLvjA9q1E=; b=hgyQTqKXfucJhdwq7gmSFs+l2vQpxRgN9jv1+mAyiW+AYhJ9x35vsOmMNLDLv6PmNZ K7JpMBSInbjd2Fg+KsOWZwF8Hc1kq0znKwo+Fl/UCBcRK+wYaDnq480hloAHTJV/h2MG ulnQcHtWP1nWcK1W0lQj1Ep1jAF8HV3CGGcMu/BXg7bK7DZtfZC+/NqokiW+zU15lw0e 21n+9C5m44/zJLxkJWU1Xw6PqKD2wBiEeUYdBQ3j3cbMh/RpZjGGf0IjkKot7gJgDnjP iTgA7vOVgjQ9xYjwRobb6CFbYAC/hxldecjuOgGX9xWWFVZZdRea/wu6AYd0f/mZNzYD e+Pg== X-Forwarded-Encrypted: i=1; AJvYcCWlTzlYm5PgaFxL+5Wl7hV1Snw+94ynKXM6GX3jCXCNX8zPDQNy1PRwO9X/yJ9H7c2Oi+SCl0ztChOpZhA=@vger.kernel.org X-Gm-Message-State: AOJu0YxyuOVb+N+FHN/7ROvSkVHZ+Ggm0RVpvxrGkH7rzUJ2n0eXsjqn DVxppMVO2sZuejPRyJrIQlF/QB8w8JWb6ruG3MGgOOgkfDI4RgO7LWQ8r5I1jA== X-Gm-Gg: AeBDievVPTMKWM8m5pfR5ZgTsk+vv+6sndEVlSy8Dsk1sHwElrLwLl1ySeaqqymbGL7 rM4EY2/9aJc2UZ+k8I1zsW+EV/T4+u5L2DWyZoqhU9LYFrulhGuEhK8gGpkmiRUJu9xzqevZUZ9 DgWQeZjFqf/TKwhCMpcoiHbAXQM0tpb6FDDgDEYPbSmfxCLeaC3ZlBl/f2ZHFepcF/cRGBGkVLY HHNTkUEV7QTyXr0bDcveO4T4I+0v10Z+Y7GLLnxA4Bv2baQ8ygP58gq79TE8GMxoK5uW1X4z2hw uosuA9YHQvREWqZlcYzciJk47CR6ZvGEP4AFRFz1Gyr9At0CstaJgvJNoqRaAHGyBodOCOT2nMd Ds3ActfrYm3ithpEHf3i8eLdaHwK0OzBfo8Kvk0E3iD9bHENgRu+T2RMCcCRDBwgRb/CJE5nuar dO54sngQaMW1YllWaAFQjWAhMxXnOb9WUu X-Received: by 2002:a05:6820:1389:b0:67d:f88f:d853 with SMTP id 006d021491bc7-68be5c5dd0amr2359578eaf.6.1775855276856; Fri, 10 Apr 2026 14:07:56 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:59::]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-423dcf9726fsm3229555fac.0.2026.04.10.14.07.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Apr 2026 14:07:56 -0700 (PDT) From: Joshua Hahn To: Johannes Weiner Cc: Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: [PATCH 8/8 RFC] mm/memcontrol: remove unused memcg_stock code Date: Fri, 10 Apr 2026 14:07:02 -0700 Message-ID: <20260410210742.550489-9-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260410210742.550489-1-joshua.hahnjy@gmail.com> References: <20260410210742.550489-1-joshua.hahnjy@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Now that all memcg_stock logic has been moved to page_counter_stock, we can remove all code related to handling memcg_stock. Note that obj_stock is untouched and is still needed. FLUSHING_CACHED_CHARGE is preserved so that it can be used by obj_stock as well. Suggested-by: Johannes Weiner Signed-off-by: Joshua Hahn --- mm/memcontrol.c | 183 ------------------------------------------------ 1 file changed, 183 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4be1638dde180..7de23ecd7cef6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1989,24 +1989,7 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) pr_cont(" are going to be killed due to memory.oom.group set\n"); } -/* - * The value of NR_MEMCG_STOCK is selected to keep the cached memcgs and their - * nr_pages in a single cacheline. This may change in future. - */ -#define NR_MEMCG_STOCK 7 #define FLUSHING_CACHED_CHARGE 0 -struct memcg_stock_pcp { - local_trylock_t lock; - uint8_t nr_pages[NR_MEMCG_STOCK]; - struct mem_cgroup *cached[NR_MEMCG_STOCK]; - - struct work_struct work; - unsigned long flags; -}; - -static DEFINE_PER_CPU_ALIGNED(struct memcg_stock_pcp, memcg_stock) = { - .lock = INIT_LOCAL_TRYLOCK(lock), -}; struct obj_stock_pcp { local_trylock_t lock; @@ -2030,47 +2013,6 @@ static void drain_obj_stock(struct obj_stock_pcp *stock); static bool obj_stock_flush_required(struct obj_stock_pcp *stock, struct mem_cgroup *root_memcg); -/** - * consume_stock: Try to consume stocked charge on this cpu. - * @memcg: memcg to consume from. - * @nr_pages: how many pages to charge. - * - * Consume the cached charge if enough nr_pages are present otherwise return - * failure. Also return failure for charge request larger than - * MEMCG_CHARGE_BATCH or if the local lock is already taken. - * - * returns true if successful, false otherwise. - */ -static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) -{ - struct memcg_stock_pcp *stock; - uint8_t stock_pages; - bool ret = false; - int i; - - if (nr_pages > MEMCG_CHARGE_BATCH || - !local_trylock(&memcg_stock.lock)) - return ret; - - stock = this_cpu_ptr(&memcg_stock); - - for (i = 0; i < NR_MEMCG_STOCK; ++i) { - if (memcg != READ_ONCE(stock->cached[i])) - continue; - - stock_pages = READ_ONCE(stock->nr_pages[i]); - if (stock_pages >= nr_pages) { - WRITE_ONCE(stock->nr_pages[i], stock_pages - nr_pages); - ret = true; - } - break; - } - - local_unlock(&memcg_stock.lock); - - return ret; -} - static void memcg_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages) { page_counter_uncharge(&memcg->memory, nr_pages); @@ -2078,51 +2020,6 @@ static void memcg_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages) page_counter_uncharge(&memcg->memsw, nr_pages); } -/* - * Returns stocks cached in percpu and reset cached information. - */ -static void drain_stock(struct memcg_stock_pcp *stock, int i) -{ - struct mem_cgroup *old = READ_ONCE(stock->cached[i]); - uint8_t stock_pages; - - if (!old) - return; - - stock_pages = READ_ONCE(stock->nr_pages[i]); - if (stock_pages) { - memcg_uncharge(old, stock_pages); - WRITE_ONCE(stock->nr_pages[i], 0); - } - - css_put(&old->css); - WRITE_ONCE(stock->cached[i], NULL); -} - -static void drain_stock_fully(struct memcg_stock_pcp *stock) -{ - int i; - - for (i = 0; i < NR_MEMCG_STOCK; ++i) - drain_stock(stock, i); -} - -static void drain_local_memcg_stock(struct work_struct *dummy) -{ - struct memcg_stock_pcp *stock; - - if (WARN_ONCE(!in_task(), "drain in non-task context")) - return; - - local_lock(&memcg_stock.lock); - - stock = this_cpu_ptr(&memcg_stock); - drain_stock_fully(stock); - clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); - - local_unlock(&memcg_stock.lock); -} - static void drain_local_obj_stock(struct work_struct *dummy) { struct obj_stock_pcp *stock; @@ -2139,86 +2036,6 @@ static void drain_local_obj_stock(struct work_struct *dummy) local_unlock(&obj_stock.lock); } -static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) -{ - struct memcg_stock_pcp *stock; - struct mem_cgroup *cached; - uint8_t stock_pages; - bool success = false; - int empty_slot = -1; - int i; - - /* - * For now limit MEMCG_CHARGE_BATCH to 127 and less. In future if we - * decide to increase it more than 127 then we will need more careful - * handling of nr_pages[] in struct memcg_stock_pcp. - */ - BUILD_BUG_ON(MEMCG_CHARGE_BATCH > S8_MAX); - - VM_WARN_ON_ONCE(mem_cgroup_is_root(memcg)); - - if (nr_pages > MEMCG_CHARGE_BATCH || - !local_trylock(&memcg_stock.lock)) { - /* - * In case of larger than batch refill or unlikely failure to - * lock the percpu memcg_stock.lock, uncharge memcg directly. - */ - memcg_uncharge(memcg, nr_pages); - return; - } - - stock = this_cpu_ptr(&memcg_stock); - for (i = 0; i < NR_MEMCG_STOCK; ++i) { - cached = READ_ONCE(stock->cached[i]); - if (!cached && empty_slot == -1) - empty_slot = i; - if (memcg == READ_ONCE(stock->cached[i])) { - stock_pages = READ_ONCE(stock->nr_pages[i]) + nr_pages; - WRITE_ONCE(stock->nr_pages[i], stock_pages); - if (stock_pages > MEMCG_CHARGE_BATCH) - drain_stock(stock, i); - success = true; - break; - } - } - - if (!success) { - i = empty_slot; - if (i == -1) { - i = get_random_u32_below(NR_MEMCG_STOCK); - drain_stock(stock, i); - } - css_get(&memcg->css); - WRITE_ONCE(stock->cached[i], memcg); - WRITE_ONCE(stock->nr_pages[i], nr_pages); - } - - local_unlock(&memcg_stock.lock); -} - -static bool is_memcg_drain_needed(struct memcg_stock_pcp *stock, - struct mem_cgroup *root_memcg) -{ - struct mem_cgroup *memcg; - bool flush = false; - int i; - - rcu_read_lock(); - for (i = 0; i < NR_MEMCG_STOCK; ++i) { - memcg = READ_ONCE(stock->cached[i]); - if (!memcg) - continue; - - if (READ_ONCE(stock->nr_pages[i]) && - mem_cgroup_is_descendant(memcg, root_memcg)) { - flush = true; - break; - } - } - rcu_read_unlock(); - return flush; -} - static void schedule_drain_work(int cpu, struct work_struct *work) { /* -- 2.52.0