From patchwork Thu Mar 4 12:30:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miaohe Lin X-Patchwork-Id: 12116049 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=-16.8 required=3.0 tests=BAYES_00, 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 9A547C433E9 for ; Thu, 4 Mar 2021 12:31:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 31F6764E6C for ; Thu, 4 Mar 2021 12:31:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 31F6764E6C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C5D026B0006; Thu, 4 Mar 2021 07:30:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C0CE26B0007; Thu, 4 Mar 2021 07:30:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AD58B6B0008; Thu, 4 Mar 2021 07:30:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0085.hostedemail.com [216.40.44.85]) by kanga.kvack.org (Postfix) with ESMTP id 914A36B0006 for ; Thu, 4 Mar 2021 07:30:59 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 3A39D181DDC2F for ; Thu, 4 Mar 2021 12:30:59 +0000 (UTC) X-FDA: 77882126238.03.320CE90 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) by imf16.hostedemail.com (Postfix) with ESMTP id 45D0B801A81D for ; Thu, 4 Mar 2021 12:30:58 +0000 (UTC) Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Drqsh65nzzlShM; Thu, 4 Mar 2021 20:28:40 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.498.0; Thu, 4 Mar 2021 20:30:42 +0800 From: Miaohe Lin To: CC: , , , , , , Subject: [PATCH 4/5] khugepaged: remove unnecessary mem_cgroup_uncharge() in collapse_[file|huge_page] Date: Thu, 4 Mar 2021 07:30:12 -0500 Message-ID: <20210304123013.23560-5-linmiaohe@huawei.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20210304123013.23560-1-linmiaohe@huawei.com> References: <20210304123013.23560-1-linmiaohe@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected X-Stat-Signature: jzghpjykeyw6on81uxsgrnk56tp8mght X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 45D0B801A81D Received-SPF: none (huawei.com>: No applicable sender policy available) receiver=imf16; identity=mailfrom; envelope-from=""; helo=szxga04-in.huawei.com; client-ip=45.249.212.190 X-HE-DKIM-Result: none/none X-HE-Tag: 1614861058-800596 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: Since commit 7ae88534cdd9 ("mm: move mem_cgroup_uncharge out of __page_cache_release()"), the mem_cgroup will be uncharged when hpage is freed. Uncharge mem_cgroup here is harmless but it looks confusing and buggy: if mem_cgroup charge failed, we will call mem_cgroup_uncharge() uncorrectly in error path because hpage is not IS_ERR_OR_NULL(). Signed-off-by: Miaohe Lin --- mm/khugepaged.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index e886a8618c33..68579cdbdc9b 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1211,8 +1211,6 @@ static void collapse_huge_page(struct mm_struct *mm, out_up_write: mmap_write_unlock(mm); out_nolock: - if (!IS_ERR_OR_NULL(*hpage)) - mem_cgroup_uncharge(*hpage); trace_mm_collapse_huge_page(mm, isolated, result); return; out: @@ -1968,8 +1966,6 @@ static void collapse_file(struct mm_struct *mm, unlock_page(new_page); out: VM_BUG_ON(!list_empty(&pagelist)); - if (!IS_ERR_OR_NULL(*hpage)) - mem_cgroup_uncharge(*hpage); /* TODO: tracepoints */ }