From patchwork Thu Aug 26 07:17:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liu Zixian X-Patchwork-Id: 503765 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 89747C4320A for ; Thu, 26 Aug 2021 07:17:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7150C60ED5 for ; Thu, 26 Aug 2021 07:17:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239628AbhHZHSc (ORCPT ); Thu, 26 Aug 2021 03:18:32 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:9366 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234415AbhHZHSc (ORCPT ); Thu, 26 Aug 2021 03:18:32 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GwDbK6TyNz8vM4; Thu, 26 Aug 2021 15:13:33 +0800 (CST) Received: from dggpemm000001.china.huawei.com (7.185.36.245) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 26 Aug 2021 15:17:43 +0800 Received: from huawei.com (10.174.177.108) by dggpemm000001.china.huawei.com (7.185.36.245) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 26 Aug 2021 15:17:42 +0800 From: Liu Zixian To: , , CC: , , Subject: [PATCH v2] mm/hugetlb: initialize hugetlb_usage in mm_init Date: Thu, 26 Aug 2021 15:17:42 +0800 Message-ID: <20210826071742.877-1-liuzixian4@huawei.com> X-Mailer: git-send-email 2.29.2.windows.3 MIME-Version: 1.0 X-Originating-IP: [10.174.177.108] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm000001.china.huawei.com (7.185.36.245) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org After fork, the child process will get incorrect (2x) hugetlb_usage. If a process uses 5 2MB hugetlb pages in an anonymous mapping, HugetlbPages: 10240 kB and then forks, the child will show, HugetlbPages: 20480 kB The reason for double the amount is because hugetlb_usage will be copied from the parent and then increased when we copy page tables from parent to child. Child will have 2x actual usage. Fix this by adding hugetlb_count_init in mm_init. Fixes: 5d317b2b6536 ("mm: hugetlb: proc: add HugetlbPages field to /proc/PID/status") Signed-off-by: Liu Zixian --- v2: 1. Create two hugetlb_count_init in hugetlb.h instead of using #ifdef in fork.c 2. Add an example to clearify this issue. --- include/linux/hugetlb.h | 9 +++++++++ kernel/fork.c | 1 + 2 files changed, 10 insertions(+) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index f7ca1a387..1faebe1cd 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -858,6 +858,11 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h, void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm); +static inline void hugetlb_count_init(struct mm_struct *mm) +{ + atomic_long_set(&mm->hugetlb_usage, 0); +} + static inline void hugetlb_count_add(long l, struct mm_struct *mm) { atomic_long_add(l, &mm->hugetlb_usage); @@ -1042,6 +1047,10 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h, return &mm->page_table_lock; } +static inline void hugetlb_count_init(struct mm_struct *mm) +{ +} + static inline void hugetlb_report_usage(struct seq_file *f, struct mm_struct *m) { } diff --git a/kernel/fork.c b/kernel/fork.c index bc94b2cc5..0dbc96ade 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1050,6 +1050,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, mm->pmd_huge_pte = NULL; #endif mm_init_uprobes_state(mm); + hugetlb_count_init(mm); if (current->mm) { mm->flags = current->mm->flags & MMF_INIT_MASK;