From patchwork Thu May 27 06:21:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12283395 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F454C47089 for ; Thu, 27 May 2021 06:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B5AD610CC for ; Thu, 27 May 2021 06:24:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234508AbhE0GZ4 (ORCPT ); Thu, 27 May 2021 02:25:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234473AbhE0GZz (ORCPT ); Thu, 27 May 2021 02:25:55 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA382C061763 for ; Wed, 26 May 2021 23:24:21 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id x18so2847766pfi.9 for ; Wed, 26 May 2021 23:24:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=7xcEWYskDBGu/bK3eKJT7YkQNy1YoQQPMH2C2+EMstk=; b=Q6/3D8pP+YPIY9c5gcugaTZWMDQovoBE/dn87+UA9E08IM6mZBijQrgLYo4IpMpwaM xdy8cDIDZRsXcysP+1i5noZsePA/87hpIsdudzFRoSVmyo6s86mwl+K+May6cNCegfkI Iy6GQGsUUytBgDnzvk2ByMnQBqgCshQLnunSjNfLLuZ7SJbQ8bSvTGmABFaPDY/N0l+j KxGtMcsR8YMEwc/ruSFE3PO+Jc0zJUDvz/FWuNZVCubkBKePUU4aNwu/7S/tQLDCiC5P u7OexXHYaa4olTIx7NkV5gtaPpWNlgCqKaTaK9gWuuWGhCsffUOgvT4jEgZxQ1DBUGzC cWTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=7xcEWYskDBGu/bK3eKJT7YkQNy1YoQQPMH2C2+EMstk=; b=oNhFC0Q4jG0I+I6kFCpsluLuDJrFys2UGfw7ZeIB8HtgDEikTZI2Dd/bNTJsrLoxu6 vEmMVjVZFiJdKD5HBJU06pZDHTzBRUeCNeGz9uScC0/4Eo6RHJGQ2mTvimgSWP6ejFzX 1u6BSAvdj9/hT9JwDATf8A9tXpx8OSQNeNBcTt30DT4ibGjsVxjOxcw6qRkYLzs/Xbw4 25k1phtV5ht1WvNVv3XMhlV9oMV9fbgUCjnzwg/PFDh/AfvAaOSaT/v7X11QQGY+0CNP hH/cLytbiCrfwafvJ/J+udg1r2a9sEdykoLYLhvyXT5RBj3wcgncq0SDZ/vUYZk/uGpZ Jrlg== X-Gm-Message-State: AOAM531OJqrTVECg6Nw9QUCYuVLtOKPZ63IIWS2jlr/brk4vi2ak4KJc ebtQL91zgUFywbDnekFkNv5Vug== X-Google-Smtp-Source: ABdhPJzrZBmPL3AYKSHKsLxo8L8abN9IDlFQW8JyPdoRceqGeMwyxDBF0enNTeguNaomtOhemc8nEw== X-Received: by 2002:a63:4d52:: with SMTP id n18mr2233081pgl.147.1622096661406; Wed, 26 May 2021 23:24:21 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.254]) by smtp.gmail.com with ESMTPSA id m5sm882971pgl.75.2021.05.26.23.24.13 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 May 2021 23:24:21 -0700 (PDT) From: Muchun Song To: willy@infradead.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, shakeelb@google.com, guro@fb.com, shy828301@gmail.com, alexs@kernel.org, richard.weiyang@gmail.com, david@fromorbit.com, trond.myklebust@hammerspace.com, anna.schumaker@netapp.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, zhengqi.arch@bytedance.com, duanxiongchun@bytedance.com, fam.zheng@bytedance.com, Muchun Song Subject: [PATCH v2 01/21] mm: list_lru: fix list_lru_count_one() return value Date: Thu, 27 May 2021 14:21:28 +0800 Message-Id: <20210527062148.9361-2-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210527062148.9361-1-songmuchun@bytedance.com> References: <20210527062148.9361-1-songmuchun@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Since commit 2788cf0c401c ("memcg: reparent list_lrus and free kmemcg_id on css offline"), the ->nr_items can be negative during memory cgroup reparenting. In this case, list_lru_count_one() returns an unusual and huge value. It can surprise users. So let it return zero when ->nr_items is negative. Signed-off-by: Muchun Song --- mm/list_lru.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/list_lru.c b/mm/list_lru.c index cd58790d0fb3..4962d48d4410 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -176,13 +176,16 @@ unsigned long list_lru_count_one(struct list_lru *lru, { struct list_lru_node *nlru = &lru->node[nid]; struct list_lru_one *l; - unsigned long count; + long count; rcu_read_lock(); l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg)); count = READ_ONCE(l->nr_items); rcu_read_unlock(); + if (unlikely(count < 0)) + count = 0; + return count; } EXPORT_SYMBOL_GPL(list_lru_count_one);