linux-kernel - 回复: [PATCH] rcu: Release per-cpu krcp page cache when CPU going offline

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Message-ID: <BYAPR11MB26324D17B990FC099919CBB7FFA00@BYAPR11MB2632.namprd11.prod.outlook.com>
Date:   Fri, 22 Jan 2021 01:44:36 +0000
From:   "Zhang, Qiang" <Qiang.Zhang@...driver.com>
To:     Uladzislau Rezki <urezki@...il.com>
CC:     "Paul E. McKenney" <paulmck@...nel.org>,
        "rcu@...r.kernel.org" <rcu@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: 回复: [PATCH] rcu: Release per-cpu krcp page cache when CPU going offline



________________________________________
发件人: Uladzislau Rezki <urezki@...il.com>
发送时间: 2021年1月22日 4:26
收件人: Zhang, Qiang
抄送: Paul E. McKenney; rcu@...r.kernel.org; linux-kernel@...r.kernel.org; urezki@...il.com
主题: Re: [PATCH] rcu: Release per-cpu krcp page cache when CPU going offline
>Hello, Qiang,

> On Thu, Jan 21, 2021 at 02:49:49PM +0800, qiang.zhang@...driver.com wrote:
> > From: Zqiang <qiang.zhang@...driver.com>
> >
> > If CPUs go offline, the corresponding krcp's page cache can
> > not be use util the CPU come back online, or maybe the CPU
> > will never go online again, this commit therefore free krcp's
> > page cache when CPUs go offline.
> >
> > Signed-off-by: Zqiang <qiang.zhang@...driver.com>
>
>Do you consider it as an issue? We have 5 pages per CPU, that is 20480 bytes.
>

Hello Rezki 

In a multi CPUs system, more than one CPUs may be offline, there are more than 5 pages,  and these offline CPUs may never go online again  or  in the process of CPUs online, there are errors, which lead to the failure of online, these scenarios will lead to the per-cpu krc page cache will never be released.

Thanks
Qiang


>--
>Vlad Rezki