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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 0304FC433DF for ; Wed, 26 Aug 2020 02:35:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9C31D206F0 for ; Wed, 26 Aug 2020 02:35:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="nZB3nTfX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C31D206F0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 209246B0003; Tue, 25 Aug 2020 22:35:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1B8A36B0005; Tue, 25 Aug 2020 22:35:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0CF1E6B0006; Tue, 25 Aug 2020 22:35:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0087.hostedemail.com [216.40.44.87]) by kanga.kvack.org (Postfix) with ESMTP id EBFC56B0003 for ; Tue, 25 Aug 2020 22:35:26 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id AD989181AEF1F for ; Wed, 26 Aug 2020 02:35:26 +0000 (UTC) X-FDA: 77191153452.16.rule26_631039027060 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id 7A514100E6903 for ; Wed, 26 Aug 2020 02:35:26 +0000 (UTC) X-HE-Tag: rule26_631039027060 X-Filterd-Recvd-Size: 4116 Received: from mail-pg1-f196.google.com (mail-pg1-f196.google.com [209.85.215.196]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Wed, 26 Aug 2020 02:35:25 +0000 (UTC) Received: by mail-pg1-f196.google.com with SMTP id 31so273182pgy.13 for ; Tue, 25 Aug 2020 19:35:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=qTTirhS4tgARwSmt2CrwMKjZEtQBfU50yJZ95gB7kI0=; b=nZB3nTfXwtirj0Dfa02h5DsBk22b7a15AQG/8Ko2SeqemhlIzMy2w39Fz8bbh4K2vO Fx4gyfYwOFf7zThB7wyYq3gwTm4oCfF00+tWqQLQ5IHYhUicQMJe9P2XjChp8LWnXu2P iom5SDmp3BW0+4qVS62AIRq5kMP56kAxjqSnQmas1O04vVMWoV22LzXVTMYT5SoSZ7QE NU/agOeI6zKO/At7M99eJzFK1s0Sg9rcOmqEpTZLK56yLXSE36ai0sOUoug8hvnduR6k NbKzXDn4VPDzl6vW910Vi2GWUk6nJhlTNP/mCMEvxJ78J2R3JqB7Tq+8iHQXAuOV2nZD JTiQ== 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=qTTirhS4tgARwSmt2CrwMKjZEtQBfU50yJZ95gB7kI0=; b=EsIMomMuwNXdVI+2V2mtvgc5v7x+17u+66vDDgWd6COFxSCuIMfrdgn8VCcVzOLZSl 9B5e5aGlf0a2JPrZJfBFU/+Q2iC36sWla2Dm4prB80Bxrg2Mzlmk6qPQD6gGhRTThfad LhZBzFj8bkL3UDH1G1ElTxZICYP5jBnnfPwoMnWGPIu+PpqX5cubM1AJJZEswhxNislx 9Q8wMR/8A3Wwu7vwcm7aRc63IIN/N8WarZwMHMm0HnJ2Dd9xG4HK/vDrLvPJjdwT0yxd R7oOXVVmj8tyBfijcAc1yE1jDnSL5nbCfmK9Zyvt9hPlFOnAY/WfERG8Qyyb+t9zW1OI 2dOg== X-Gm-Message-State: AOAM532r+uEnBD0KeIruTyNp7+D7GrAWogxZuVLNzUBIWwTFJmEmUft3 cbOPe/7ufb2Qa3wMSTfNC0KBx2JZyM865z0HeRG/8Q== X-Google-Smtp-Source: ABdhPJxqehxvxHho/3bJPXX1aOLT+XLYCBV/K23o3fqsovbLI048DponkAKzpgPKb3HyHIcb6ngfLWsifOHzCM+sS3U= X-Received: by 2002:a62:6497:: with SMTP id y145mr10157831pfb.97.1598409324792; Tue, 25 Aug 2020 19:35:24 -0700 (PDT) MIME-Version: 1.0 References: <20200822095328.61306-1-songmuchun@bytedance.com> <20200825152509.GO1509399@tassilo.jf.intel.com> In-Reply-To: <20200825152509.GO1509399@tassilo.jf.intel.com> From: Muchun Song Date: Wed, 26 Aug 2020 10:34:48 +0800 Message-ID: Subject: Re: [Phishing Risk] [External] Re: [PATCH] mm/hugetlb: Fix a race between hugetlb sysctl handlers To: Andi Kleen Cc: mike.kravetz@oracle.com, Andrew Morton , npiggin@suse.de, agl@us.ibm.com, nacc@us.ibm.com, Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 7A514100E6903 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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: HI Andi, On Tue, Aug 25, 2020 at 11:34 PM Andi Kleen wrote: > > > Fixes: e5ff215941d5 ("hugetlb: multiple hstates for multiple page sizes") > > I don't think the Fixes line is correct. The original patch > just used a global variable and didn't have this race. > It must have been added later in some other patch that added > hugetlb_sysctl_handler_common. I don't agree with you. The 'e5ff215941d5' is not used a global variable. Below is the code snippet of this patch. Thanks. @@ -1037,8 +1109,19 @@ int hugetlb_sysctl_handler(struct ctl_table *table, int write, struct file *file, void __user *buffer, size_t *length, loff_t *ppos) { + struct hstate *h = &default_hstate; + unsigned long tmp; Here is a local variable of tmp. + + if (!write) + tmp = h->max_huge_pages; + + table->data = &tmp; + table->maxlen = sizeof(unsigned long); proc_doulongvec_minmax(table, write, file, buffer, length, ppos); - max_huge_pages = set_max_huge_pages(max_huge_pages); + + if (write) + h->max_huge_pages = set_max_huge_pages(h, tmp); + return 0; } > > -Andi -- Yours, Muchun