linux-kernel - Re: [RFC PATCH] rework memory hotplug onlining

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Message-ID: <20170316174050.GA13654@dhcp22.suse.cz>
Date:   Thu, 16 Mar 2017 18:40:51 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     "Kani, Toshimitsu" <toshi.kani@....com>
Cc:     "zhenzhang.zhang@...wei.com" <zhenzhang.zhang@...wei.com>,
        "tangchen@...fujitsu.com" <tangchen@...fujitsu.com>,
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Subject: Re: [RFC PATCH] rework memory hotplug onlining

On Thu 16-03-17 17:19:34, Kani, Toshimitsu wrote:
> On Thu, 2017-03-16 at 09:54 +0100, Michal Hocko wrote:
> > On Wed 15-03-17 23:08:14, Kani, Toshimitsu wrote:
> > > On Wed, 2017-03-15 at 10:13 +0100, Michal Hocko wrote:
>  :
> > > > -	zone = page_zone(pfn_to_page(valid_start));
> > > 
> > > Please do not remove the fix made in a96dfddbcc043. zone needs to
> > > be set from valid_start, not from start_pfn.
> > 
> > Thanks for pointing this out. I was scratching my head about this
> > part but was too tired from previous git archeology so I didn't check
> > the history of this particular part.
> >
> > I will restore the original behavior but before I do that I am really
> > curious whether partial memblocks are even supported for onlining.
> > Maybe I am missing something but I do not see any explicit checks for
> > NULL struct page when we set zone boundaries or online a memblock. Is
> > it possible those memblocks are just never hotplugable?
> 
> check_hotplug_memory_range() checks if a given range is aligned by the
> section size.

Ohh, right you are! I have completely missed check_hotplug_memory_range.
Thanks for pointing it out.

-- 
Michal Hocko
SUSE Labs