From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D3C82DCB5D for ; Tue, 29 Apr 2025 23:05:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745967927; cv=none; b=byc8aCiTLa3v4a+rckqwrYLDbOajtlYhGvYFcgnnFqdSdEfqqhmsI1B6JT1QllOG1vXslAicnGAk0sBoRD/SedoQwaRkfBhhmoGv9jVR+wEBauHCXAZnL4fyVAvUmlsq3Pb0+4UDTxPzYKebLz+yomE4UE19LyYhNSbhbUqgJHs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745967927; c=relaxed/simple; bh=vUhnoYWgld5Ear31+0RTM7usI0oTO/ydOl8T94r/4j8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LMpLwCdljUtPljJH8p6uTXUcnWpzUpIbB90BMlbRs9gRhpdSAekKjfzqdDYhvpMvav3x9DrbXH13W05PCnZLYzpGZEbh3ypTdyH33ZAwb0NYI4gl+xA30MAW7LAPgAtTWbMuLLqTPm/8rVlat6NDIhFwOavpuKqAYUzaDoZHqyA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=FpN7Cos5; arc=none smtp.client-ip=95.215.58.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="FpN7Cos5" 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=1745967922; 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: in-reply-to:in-reply-to:references:references; bh=+wZ3v2muB0VupF4eSm9lwfoOuI+XDtB2dNKm1AuFXCU=; b=FpN7Cos5+LvGlJ0uN4wUjtj7q62hwDzl34qGZWAa8an12kny3cW+RWdWjX0voaSFS2d8ns baVq1k2+kMkUxX+1intyzYgXU/SVc8vJTJp1Wtg+sOl2e5cmA4RB4DfpCipF0xy/CoWPWD eKZuGCqqdWXUaFLaYqD9I2TjwG+p+hs= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Sebastian Andrzej Siewior , Vlastimil Babka , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH 4/4] memcg: no irq disable for memcg stock lock Date: Tue, 29 Apr 2025 16:04:28 -0700 Message-ID: <20250429230428.1935619-5-shakeel.butt@linux.dev> In-Reply-To: <20250429230428.1935619-1-shakeel.butt@linux.dev> References: <20250429230428.1935619-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT There is no need to disable irqs to use memcg per-cpu stock, so let's just not do that. One consequence of this change is if the kernel while in task context has the memcg stock lock and that cpu got interrupted. The memcg charges on that cpu in the irq context will take the slow path of memcg charging. However that should be super rare and should be fine in general. Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8f31b35ddcb3..25bd312d0455 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1827,12 +1827,11 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) { struct memcg_stock_pcp *stock; uint8_t stock_pages; - unsigned long flags; bool ret = false; int i; if (nr_pages > MEMCG_CHARGE_BATCH || - !local_trylock_irqsave(&memcg_stock.lock, flags)) + !local_trylock(&memcg_stock.lock)) return ret; stock = this_cpu_ptr(&memcg_stock); @@ -1849,7 +1848,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) break; } - local_unlock_irqrestore(&memcg_stock.lock, flags); + local_unlock(&memcg_stock.lock); return ret; } @@ -1893,18 +1892,17 @@ static void drain_stock_fully(struct memcg_stock_pcp *stock) static void drain_local_memcg_stock(struct work_struct *dummy) { struct memcg_stock_pcp *stock; - unsigned long flags; if (WARN_ONCE(!in_task(), "drain in non-task context")) return; - local_lock_irqsave(&memcg_stock.lock, flags); + local_lock(&memcg_stock.lock); stock = this_cpu_ptr(&memcg_stock); drain_stock_fully(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); - local_unlock_irqrestore(&memcg_stock.lock, flags); + local_unlock(&memcg_stock.lock); } static void drain_local_obj_stock(struct work_struct *dummy) @@ -1944,7 +1942,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) VM_WARN_ON_ONCE(mem_cgroup_is_root(memcg)); if (nr_pages > MEMCG_CHARGE_BATCH || - !local_trylock_irqsave(&memcg_stock.lock, flags)) { + !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. @@ -1979,7 +1977,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) WRITE_ONCE(stock->nr_pages[i], nr_pages); } - local_unlock_irqrestore(&memcg_stock.lock, flags); + local_unlock(&memcg_stock.lock); } static bool is_memcg_drain_needed(struct memcg_stock_pcp *stock, -- 2.47.1