linux-kernel - Re: [PATCH v7 3/7] set_memory: allow set_direct_map_*

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Date:   Tue, 27 Oct 2020 11:48:45 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     David Hildenbrand <david@...hat.com>
Cc:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
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Subject: Re: [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for
 multiple pages

On Tue, Oct 27, 2020 at 09:12:23AM +0100, David Hildenbrand wrote:
> On 26.10.20 20:01, Edgecombe, Rick P wrote:
> > On Mon, 2020-10-26 at 10:37 +0200, Mike Rapoport wrote:
> >> +++ b/arch/x86/mm/pat/set_memory.c
> >> @@ -2184,14 +2184,14 @@ static int __set_pages_np(struct page *page,
> >> int numpages)
> >>         return __change_page_attr_set_clr(&cpa, 0);
> >>  }
> >>  
> >> -int set_direct_map_invalid_noflush(struct page *page)
> >> +int set_direct_map_invalid_noflush(struct page *page, int numpages)
> >>  {
> >> -       return __set_pages_np(page, 1);
> >> +       return __set_pages_np(page, numpages);
> >>  }
> >>  
> >> -int set_direct_map_default_noflush(struct page *page)
> >> +int set_direct_map_default_noflush(struct page *page, int numpages)
> >>  {
> >> -       return __set_pages_p(page, 1);
> >> +       return __set_pages_p(page, numpages);
> >>  }
> > 
> > Somewhat related to your other series, this could result in large NP
> > pages and trip up hibernate.
> > 
> 
> It feels somewhat desirable to disable hibernation once secretmem is
> enabled, right? Otherwise you'll be writing out your secrets to swap,
> where they will remain even after booting up again ...
> 
> Skipping secretmem pages when hibernating is the wrong approach I guess ...

Completely agree.
I'll look into preventing hibernation from touching secretmem.

> -- 
> Thanks,
> 
> David / dhildenb
> 

-- 
Sincerely yours,
Mike.