From patchwork Thu Mar 23 04:00:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13184913 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED83EC77B60 for ; Thu, 23 Mar 2023 04:00:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229485AbjCWEA4 (ORCPT ); Thu, 23 Mar 2023 00:00:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229615AbjCWEAx (ORCPT ); Thu, 23 Mar 2023 00:00:53 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0677520040 for ; Wed, 22 Mar 2023 21:00:45 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id x4-20020a170902ec8400b001a1a5f6f272so10187079plg.1 for ; Wed, 22 Mar 2023 21:00:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1679544045; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=0V6KepxSWjC0U8YUMhyf5sEsW80RflfKR4tDJnFyjUM=; b=nvFwhwj7qGyMPQaTPrzYFw+T0XNSe66OQzM5b4pjwLTwVBRy9Yg/AbwpYFnRMIM5gG L465fbRhjctsBw/iYduTrtP7LUUTB2pfnwQVaagEQM0GyAtfd40drA654+PpJ27hrtIB BUWcp/c32KQ98SFLCZ9FSHYNM6vaide1p2wRQYwdJvG/bU3/l2g1YAjLINeXoxbcrV2W 3/G5Y/6fhAJDfUsgxXfVWzP78YqVFCMwh/+/7IKP9AVvA+7qfhsyQkLxneMASA+CreO0 VfuwrktKMl3lyTDdGpOXeKO210ebUx1dz4XnfSvMg+6i1Ne/G/0TP1oqkrL/txGwmyNx VJtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679544045; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0V6KepxSWjC0U8YUMhyf5sEsW80RflfKR4tDJnFyjUM=; b=AVjl9Plwj8jIH/rsqQScIOJaPaHPTjKrFfjoXYG+eetY5yyQu9JSlnZgt9Onf128CA bp1CDvUHIl23qvpJvxul4ZV+lMdVJ0K1HhdCewTbBb4vCZLAXMVrR05Aev67a0Jfrchu CuCZQeQxrGhBi3SOZ3QdBu2A6a6qJhVHBe7Cn1jPcrL5eTeBdvdhdDt+aEDJid64aTh7 Au7IasLDS1wEHZ/526Fm5Sx5UG6jlzNsa56iomBm6QFLFcnK+kXPqfBS1TpMenW8G2bM ZfK6fMgAQINgwUnlamhocBHQuigosYA4VWWIbG+KlCR54YcsI2IUf0imUtreTqfwCr+F Ek+A== X-Gm-Message-State: AO0yUKXYOSvHhlbJdQ/HgOYzUDdRHb/vcFdercAbDxh1CJSjxeXCklG0 ghOlxFVXx/8wk2Wtaqh0DD4bzDc6aUpqAWlz X-Google-Smtp-Source: AK7set+NjW/4AXEB5d0IG7XiVNOSp7doL59qiTn9uvLqiFnoG/BqWGCoWZHV7SR3pQA/2uxuP1t6d8Miz+ziUaX1 X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:6a00:851:b0:628:30d:2d2f with SMTP id q17-20020a056a00085100b00628030d2d2fmr2879444pfk.5.1679544045305; Wed, 22 Mar 2023 21:00:45 -0700 (PDT) Date: Thu, 23 Mar 2023 04:00:32 +0000 In-Reply-To: <20230323040037.2389095-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230323040037.2389095-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.rc1.284.g88254d51c5-goog Message-ID: <20230323040037.2389095-3-yosryahmed@google.com> Subject: [RFC PATCH 2/7] memcg: do not disable interrupts when holding stats_flush_lock From: Yosry Ahmed To: Tejun Heo , Josef Bacik , Jens Axboe , Zefan Li , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton Cc: Vasily Averin , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, Yosry Ahmed Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The rstat flushing code was modified so that we do not disable interrupts when we hold the global rstat lock. Do the same for stats_flush_lock on the memcg side to avoid unnecessarily disabling interrupts throughout flushing. Since the code exclusively uses trylock to acquire this lock, it should be fine to hold from interrupt contexts or normal contexts without disabling interrupts as a deadlock cannot occur. For interrupt contexts we will return immediately without flushing anyway. Signed-off-by: Yosry Ahmed --- mm/memcontrol.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5abffe6f8389..e0e92b38fa51 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -636,15 +636,17 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) static void __mem_cgroup_flush_stats(void) { - unsigned long flag; - - if (!spin_trylock_irqsave(&stats_flush_lock, flag)) + /* + * This lock can be acquired from interrupt context, but we only acquire + * using trylock so it should be fine as we cannot cause a deadlock. + */ + if (!spin_trylock(&stats_flush_lock)) return; flush_next_time = jiffies_64 + 2*FLUSH_TIME; cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup); atomic_set(&stats_flush_threshold, 0); - spin_unlock_irqrestore(&stats_flush_lock, flag); + spin_unlock(&stats_flush_lock); } void mem_cgroup_flush_stats(void)