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From:   Pavel Tatashin <pasha.tatashin@oracle.com>
Date:   Fri, 15 Jun 2018 12:02:17 -0400
Message-ID: <CAGM2reYA=jqL7KO6j9Tcjxyeb_=7aCfyekdO_aaRSZYv7_WeVg@mail.gmail.com>
Subject: Re: [PATCH v3] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved
To:     osalvador@techadventures.net
Cc:     mhocko@kernel.org, n-horiguchi@ah.jp.nec.com,
        Linux Memory Management List <linux-mm@kvack.org>,
        osalvador@suse.de, Steven Sistare <steven.sistare@oracle.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        willy@infradead.org, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, mingo@kernel.org,
        dan.j.williams@intel.com, ying.huang@intel.com
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> Hi Pavel,
>
> I think this makes a lot of sense.
> Since Naoya is out until Wednesday, maybe I give it a shot next week and see if I can gather some numbers.

Hi Oscar,

Thank you for the offer to do this. Since, sched_clock() is not yet
initialized at the time zero_resv_unavail() is called, it is difficult
to measure it during boot. But, I had x86 early boot timestamps
patches handy, so I could measure, thus decided to submit the patch.
http://lkml.kernel.org/r/20180615155733.1175-1-pasha.tatashin@oracle.com

Thank you,
Pavel

>
> >
> > Thank you,
> > Pasha
> >
> > >
> > > > ---
> > > >  arch/x86/kernel/e820.c | 15 ++++++++++++---
> > > >  1 file changed, 12 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> > > > index d1f25c831447..c88c23c658c1 100644
> > > > --- a/arch/x86/kernel/e820.c
> > > > +++ b/arch/x86/kernel/e820.c
> > > > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void)
> > > >  {
> > > >   int i;
> > > >   u64 end;
> > > > + u64 addr = 0;
> > > >
> > > >   /*
> > > >    * The bootstrap memblock region count maximum is 128 entries
> > > > @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void)
> > > >           struct e820_entry *entry = &e820_table->entries[i];
> > > >
> > > >           end = entry->addr + entry->size;
> > > > +         if (addr < entry->addr)
> > > > +                 memblock_reserve(addr, entry->addr - addr);
> > > > +         addr = end;
> > > >           if (end != (resource_size_t)end)
> > > >                   continue;
> > > >
> > > > +         /*
> > > > +          * all !E820_TYPE_RAM ranges (including gap ranges) are put
> > > > +          * into memblock.reserved to make sure that struct pages in
> > > > +          * such regions are not left uninitialized after bootup.
> > > > +          */
> > > >           if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN)
> > > > -                 continue;
> > > > -
> > > > -         memblock_add(entry->addr, entry->size);
> > > > +                 memblock_reserve(entry->addr, entry->size);
> > > > +         else
> > > > +                 memblock_add(entry->addr, entry->size);
> > > >   }
> > > >
> > > >   /* Throw away partial pages: */
> > > > --
> > > > 2.7.4
> > >
> > > --
> > > Michal Hocko
> > > SUSE Labs
> > >
> >
>
> Best Regards
> Oscar Salvador
>