From patchwork Thu Apr 10 21:06:23 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 14047213 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BD14C369A6 for ; Thu, 10 Apr 2025 21:06:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 585D928013B; Thu, 10 Apr 2025 17:06:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 533CC280138; Thu, 10 Apr 2025 17:06:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 425E028013B; Thu, 10 Apr 2025 17:06:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 23B66280138 for ; Thu, 10 Apr 2025 17:06:49 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id DA47E1A14C2 for ; Thu, 10 Apr 2025 21:06:49 +0000 (UTC) X-FDA: 83319368538.12.7DE1DC8 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) by imf01.hostedemail.com (Postfix) with ESMTP id 28BC44000B for ; Thu, 10 Apr 2025 21:06:47 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="Ode1u+//"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf01.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.187 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744319208; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=eqKHtHIKdZRFnIVHPqA+xldT1tQxP5YolVvro+sDJq8=; b=Y/f8WtlgD7RoigpMDvp8edbOAZVq1aN7FIxD0XRi9eVdXj4foqa45+3TL2n7XE0jkIlnbs QGW7ECobZu3xsygW/6PY5hXaP8soe2omHttIVrhKm8Xg+VU46kQ8AHqjdBUaDW/CbEDguV OwaB1EYlRqORlx3PSChtbYtWXuAUuhM= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="Ode1u+//"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf01.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.187 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744319208; a=rsa-sha256; cv=none; b=aU48E/OER5d5RWv5CtyJsNHChDwPBe2/ke24z7xp32tl7xt0ZV37G2zCK6xNbMmnh78PCh W2YobdC8/PoX8h+WF/z+HvPg/JtYryBZs9kBjRGYFhk69h0UQSn7bRtBvfyfszJ1/z1B1j lHy71jrwcXOCjW+qtyGDhgGtZGSwipo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1744319206; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=eqKHtHIKdZRFnIVHPqA+xldT1tQxP5YolVvro+sDJq8=; b=Ode1u+//ukIHUqPcNQtouHpRbufdKBk3KfzUHB5JsjsEMVMCVortoXL7MeQBO9APmXLg8J kcU/d4xYIS8p+PIAgS4vyn26X1t0BrOV2pCnpP80Hh6xL3weqrt+klui2Y5E7D3RbkdV1L +DBTQFXnjdOJH8zOkVmoP2fSb29t8DU= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Yosry Ahmed , Waiman Long , Vlastimil Babka , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH] memcg: decouple memcg_hotplug_cpu_dead from stock_lock Date: Thu, 10 Apr 2025 14:06:23 -0700 Message-ID: <20250410210623.1016767-1-shakeel.butt@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam01 X-Stat-Signature: 6186as8wwdmtmpcskjj69hfme98bfc1s X-Rspam-User: X-Rspamd-Queue-Id: 28BC44000B X-HE-Tag: 1744319207-874781 X-HE-Meta: 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 IULkIw+F bx2RLpud8DWb4We2+bIinL+Dqp4Q+reSPzyR9Wt2wm/Zf55DP/7bxFJEzHv/hNd3GKKjh26lx2y/tnOWxrLJiuk/jijnJODHISqRTt5ZNtXHyszU6us+ieZ4LS/UHhThKia/4DMHcXwSkbYBdWqsAzkdf1i9h1aR9xJM2/FxOfIw+ceoxZ79bLPUyONtBpBNowvCVoFyfx9YZQ9UXz6tLiIHqu6whYXj1BrmP 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: The function memcg_hotplug_cpu_dead works on the stock of a remote dead CPU and drain_obj_stock works on the given stock instead of local stock, so there is no need to take local stock_lock anymore. Signed-off-by: Shakeel Butt Acked-by: Roman Gushchin --- mm/memcontrol.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f23a4d0ad239..2178a051bd09 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1789,7 +1789,7 @@ static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { }; static DEFINE_MUTEX(percpu_charge_mutex); -static void drain_obj_stock(struct memcg_stock_pcp *stock); +static void __drain_obj_stock(struct memcg_stock_pcp *stock); static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg); @@ -1873,7 +1873,7 @@ static void drain_local_stock(struct work_struct *dummy) local_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); - drain_obj_stock(stock); + __drain_obj_stock(stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); @@ -1964,10 +1964,10 @@ static int memcg_hotplug_cpu_dead(unsigned int cpu) stock = &per_cpu(memcg_stock, cpu); - /* drain_obj_stock requires stock_lock */ - local_lock_irqsave(&memcg_stock.stock_lock, flags); - drain_obj_stock(stock); - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + local_irq_save(flag); + /* stock of a remote dead cpu, no need for stock_lock. */ + __drain_obj_stock(stock); + local_irq_restore(flag); drain_stock(stock); @@ -2837,7 +2837,11 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, return ret; } -static void drain_obj_stock(struct memcg_stock_pcp *stock) +/* + * Works on the given stock. The callers are responsible for the proper locking + * for the local or remote stocks. + */ +static void __drain_obj_stock(struct memcg_stock_pcp *stock) { struct obj_cgroup *old = READ_ONCE(stock->cached_objcg); @@ -2925,7 +2929,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, stock = this_cpu_ptr(&memcg_stock); if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */ - drain_obj_stock(stock); + __drain_obj_stock(stock); obj_cgroup_get(objcg); stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;