linux-kernel - Re: [PATCH v6 3/6] mce: fix set_mce_nospec to always unmap the whole page

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Date:   Tue, 22 Mar 2022 22:45:01 +0000
From:   Jane Chu <jane.chu@...cle.com>
To:     Christoph Hellwig <hch@...radead.org>
CC:     "david@...morbit.com" <david@...morbit.com>,
        "djwong@...nel.org" <djwong@...nel.org>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>,
        "dave.jiang@...el.com" <dave.jiang@...el.com>,
        "agk@...hat.com" <agk@...hat.com>,
        "snitzer@...hat.com" <snitzer@...hat.com>,
        "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "ira.weiny@...el.com" <ira.weiny@...el.com>,
        "willy@...radead.org" <willy@...radead.org>,
        "vgoyal@...hat.com" <vgoyal@...hat.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>
Subject: Re: [PATCH v6 3/6] mce: fix set_mce_nospec to always unmap the whole
 page

On 3/22/2022 1:44 AM, Christoph Hellwig wrote:
> On Sat, Mar 19, 2022 at 12:28:30AM -0600, Jane Chu wrote:
>> Mark poisoned page as not present, and to reverse the 'np' effect,
>> restate the _PAGE_PRESENT bit. Please refer to discussions here for
>> reason behind the decision.
>> https://lore.kernel.org/all/CAPcyv4hrXPb1tASBZUg-GgdVs0OOFKXMXLiHmktg_kFi7YBMyQ@mail.gmail.com/
> 
> I think it would be good to summarize the conclusion here instead of
> just linking to it.

Sure, will do.

> 
>> +static int _set_memory_present(unsigned long addr, int numpages)
>> +{
>> +	return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_PRESENT), 0);
>> +}
> 
> What is the point of this trivial helper with a single caller?
> 

Okay, will remove the helper.

thanks!
-jane