linux-kernel - Re: [PATCH -next v2] mm, proc: collect percpu free pages into the free pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4687e93d-9245-300e-6193-d5428a76c9b8@huawei.com>
Date:   Tue, 23 Aug 2022 21:12:03 +0800
From:   Liu Shixin <liushixin2@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        huang ying <huang.ying.caritas@...il.com>,
        Aaron Lu <aaron.lu@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        "Michal Hocko" <mhocko@...e.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Kemi Wang <kemi.wang@...el.com>,
        "Kefeng Wang" <wangkefeng.wang@...wei.com>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
Subject: Re: [PATCH -next v2] mm, proc: collect percpu free pages into the
 free pages

On 2022/8/23 5:13, Andrew Morton wrote:
> On Mon, 22 Aug 2022 14:12:07 -0700 Andrew Morton <akpm@...ux-foundation.org> wrote:
>
>> Prevention of races against zone/node hotplug?
> I meant "cpu/node", of course.
> .
Thanks for your advice, but I didn't quite understand what you meant.
Do you mean that I should use cpus_read_lock() to protect cpu hotplug just like this?
+       cpus_read_lock();
        for_each_online_cpu(cpu)
                sum += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
+       cpus_read_unlock();

I see there is some areas were not protected by the cpus_{read/write}_lock, so I was confused
as to whether I should add it.

I want to replace for_each_zone with for_each_populated_zone, what else should I do to protect
node hotplug.

Thanks.