From mboxrd@z Thu Jan 1 00:00:00 1970 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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 2CA54C2BA17 for ; Mon, 6 Apr 2020 16:51:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E2D1F24975 for ; Mon, 6 Apr 2020 16:51:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZFKn/MBG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E2D1F24975 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7DDCF8E004C; Mon, 6 Apr 2020 12:51:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 78EE28E000D; Mon, 6 Apr 2020 12:51:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6A4958E004C; Mon, 6 Apr 2020 12:51:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0138.hostedemail.com [216.40.44.138]) by kanga.kvack.org (Postfix) with ESMTP id 530A28E000D for ; Mon, 6 Apr 2020 12:51:53 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1A5EB9880 for ; Mon, 6 Apr 2020 16:51:53 +0000 (UTC) X-FDA: 76678022106.30.house03_84d5994ae551f X-HE-Tag: house03_84d5994ae551f X-Filterd-Recvd-Size: 3657 Received: from mail-il1-f193.google.com (mail-il1-f193.google.com [209.85.166.193]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Mon, 6 Apr 2020 16:51:52 +0000 (UTC) Received: by mail-il1-f193.google.com with SMTP id k29so164827ilg.0 for ; Mon, 06 Apr 2020 09:51:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Z5fWlXyWb88bfpyEJzmhbUO6WJPRVvrcJIncOYz7X8w=; b=ZFKn/MBGgdcG8Cr1suGBfsSdLS5zuj6cpbv3A3gs/NpRUeXGWlecBh3fzv+d00RNIr /+SdLkcaZUkoZ7Rx9Eoiy/uJRhpP/ypdMkWXUIPKsUGFZCxAAVpIiXC2LM3z0ZVWjlwD 1oZdx0jh7LqPrDPiPHZIgYZxdy7d6sayYxoWeZN6lSlKWnVmfDUyuUoGL9BODYQMY2Ou 03oRbPV3SnaoDS1TXWQomwh9AK5OEVmVXXUy13Cu2R5QIKA4QVSD2y+PdFOcnmzHMjrB 0lFHwOkmf+55ku/V9PfN7RTfb11pdssnTtyJGrzm2sniYqagElYbSuR+1M8aRf9Bkaj2 JjFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Z5fWlXyWb88bfpyEJzmhbUO6WJPRVvrcJIncOYz7X8w=; b=gNOUBC2E09rEYO2X+awxTk2Yg87ATTd6Hj3swt77OVK0XIQYk+j1rljIv5qGDQaoWk /kIA8UyM0w9dt8Sh210NWBbIajAVV7X2RkPk9G30BD5L44cxltVvX4+XBCFnTuCAXSrM jnVGXrMuRxdv/PUrk9js92MLrvQmDTEoDBEkCzMoJuMerTlSaCSarwHsINPgD2eMWL54 DNicJR9h4RGK8ABA5fb8ATV2lfpEWpu0BZhqPZ/3p9MaPjjUq8tjlKozg+Xh1lP5lHak HNa+AcYcy2Epu6cE66BOYvAM/1u5m7j+J2PkohXu/b5A6DgjBTqGxdzkJuiBotjE+/le FupQ== X-Gm-Message-State: AGi0PubqsO1Hxh/9ERBE1FMDCHP1P1uWtBJibl1LjF04CLI4ucjN+WeM 5VucZgN9JLxpeXa+2skRCDzfTZvFpZSx0ubndaM= X-Google-Smtp-Source: APiQypLWv88J7kW2nhRzUOmXTSUYlrWcuOcSNYDO2tO5nF7MEAVrICwSXzsq6vgDfIOhh70bjFf/20SGR1nS1iOJTvg= X-Received: by 2002:a92:d105:: with SMTP id a5mr226098ilb.142.1586191912174; Mon, 06 Apr 2020 09:51:52 -0700 (PDT) MIME-Version: 1.0 References: <1586188134-17038-1-git-send-email-laoar.shao@gmail.com> <20200406164251.GE21484@bombadil.infradead.org> In-Reply-To: <20200406164251.GE21484@bombadil.infradead.org> From: Yafang Shao Date: Tue, 7 Apr 2020 00:51:16 +0800 Message-ID: Subject: Re: [PATCH v2] mm, memcg: fix error return value of mem_cgroup_css_alloc() To: Matthew Wilcox Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Linux MM Content-Type: text/plain; charset="UTF-8" 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: On Tue, Apr 7, 2020 at 12:42 AM Matthew Wilcox wrote: > > On Mon, Apr 06, 2020 at 11:48:54PM +0800, Yafang Shao wrote: > > @@ -2717,8 +2717,12 @@ static int memcg_alloc_cache_id(void) > > > > id = ida_simple_get(&memcg_cache_ida, > > 0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL); > > - if (id < 0) > > + if (id < 0) { > > + if (id == -ENOSPC) > > + id = -EBUSY; > > + > > return id; > > + } > > This seems more complex than my original suggestion? > I thought the (id < 0) is an unlikely case, writing it like this only checks id once for the most common case, while your original suggestion will check id twice if the compiler is not good enough. But that is not a big problem, I can change it as you suggestion. Your suggestion is more readable. Thanks Yafang