linux-kernel - Re: Infinite looping observed in __offline

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Date:   Thu, 23 Aug 2018 09:25:43 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Haren Myneni <haren@...ux.vnet.ibm.com>,
        n-horiguchi@...jp.nec.com, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, kamezawa.hiroyu@...fujitsu.com,
        mgorman@...e.de
Subject: Re: Infinite looping observed in __offline_pages

On Wed 22-08-18 11:58:02, Mike Kravetz wrote:
> On 08/22/2018 02:30 AM, Aneesh Kumar K.V wrote:
[...]
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index 4eb6e824a80c..f9bdea685cf4 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1338,7 +1338,8 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
> >  				return pfn;
> >  			if (__PageMovable(page))
> >  				return pfn;
> > -			if (PageHuge(page)) {
> > +			if (IS_ENABLED(CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION) &&
> > +			    PageHuge(page)) {
> 
> How about using hugepage_migration_supported instead?  It would automatically
> catch those non-migratable huge page sizes.  Something like:
> 
> 			if (PageHuge(page) &&
> 			    hugepage_migration_supported(page_hstate(page))) {

Ohh, definitely, this is much better.
-- 
Michal Hocko
SUSE Labs