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From: Michal Hocko <mhocko@suse.com>
To: zhong jiang <zhongjiang@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	vbabka@suse.cz, linux-mm@kvack.org
Subject: Re: [mmotm] mm/page_owner: align with pageblock_nr_pages
Date: Wed, 6 Dec 2017 09:03:05 +0100	[thread overview]
Message-ID: <20171206080305.GA16386@dhcp22.suse.cz> (raw)
In-Reply-To: <5A275987.3070001@huawei.com>

On Wed 06-12-17 10:44:23, zhong jiang wrote:
> On 2017/12/6 8:58, Andrew Morton wrote:
> > On Mon, 4 Dec 2017 21:48:04 +0800 zhong jiang <zhongjiang@huawei.com> wrote:
> >
> >> Currently, init_pages_in_zone walk the zone in pageblock_nr_pages
> >> steps.  MAX_ORDER_NR_PAGES is possible to have holes when
> >> CONFIG_HOLES_IN_ZONE is set. it is likely to be different between
> >> MAX_ORDER_NR_PAGES and pageblock_nr_pages. if we skip the size of
> >> MAX_ORDER_NR_PAGES, it will result in the second 2M memroy leak.
> >>
> >> meanwhile, the change will make the code consistent. because the
> >> entire function is based on the pageblock_nr_pages steps.
> >>
> >> ...
> >>
> >> --- a/mm/page_owner.c
> >> +++ b/mm/page_owner.c
> >> @@ -527,7 +527,7 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
> >>  	 */
> >>  	for (; pfn < end_pfn; ) {
> >>  		if (!pfn_valid(pfn)) {
> >> -			pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
> >> +			pfn = ALIGN(pfn + 1, pageblock_nr_pages);
> >>  			continue;
> >>  		}
> > I *think* Michal and Vlastimil will be OK with this as-newly-presented.
> > Guys, can you please have another think?
> According to Vlastimil's comment,  it is not simple as it looks to cover all corners.
> Maybe  architecture need explicit define the hole granularity to use correctly.
> so far,  I have no a good idea to solve it perfectly. 
> Anyway. I will go further to find out.

Yes please! The thing is clear as mud right now and doing cosmetic
changes without further clarification doesn't help to improve the
situation much.
-- 
Michal Hocko
SUSE Labs

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      reply	other threads:[~2017-12-06  8:03 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-04 13:48 zhong jiang
2017-12-06  0:58 ` Andrew Morton
2017-12-06  2:44   ` zhong jiang
2017-12-06  8:03     ` Michal Hocko [this message]

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