From: Mel Gorman <mgorman@techsingularity.net>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org
Subject: Re: [PATCH 1/2] mm, pageblock: make sure pageblock won't exceed mem_sectioin
Date: Wed, 5 Dec 2018 15:37:33 +0000 [thread overview]
Message-ID: <20181205153733.GB23260@techsingularity.net> (raw)
In-Reply-To: <20181205120820.3gbhfvxgmclvj3wu@master>
On Wed, Dec 05, 2018 at 12:08:20PM +0000, Wei Yang wrote:
> On Wed, Dec 05, 2018 at 11:15:13AM +0000, Mel Gorman wrote:
> >On Wed, Dec 05, 2018 at 05:19:04PM +0800, Wei Yang wrote:
> >> When SPARSEMEM is used, there is an indication that pageblock is not
> >> allowed to exceed one mem_section. Current code doesn't have this
> >> constrain explicitly.
> >>
> >> This patch adds this to make sure it won't.
> >>
> >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> >
> >Is this even possible? This would imply that the section size is smaller
> >than max order which would be quite a crazy selection for a sparesemem
> >section size. A lot of assumptions on the validity of PFNs within a
> >max-order boundary would be broken with such a section size. I'd be
> >surprised if such a setup could even boot, let alone run.
>
> pageblock_order has two definitions.
>
> #define pageblock_order HUGETLB_PAGE_ORDER
>
> #define pageblock_order (MAX_ORDER-1)
>
> If CONFIG_HUGETLB_PAGE is not enabled, pageblock_order is related to
> MAX_ORDER, which ensures it is smaller than section size.
>
> If CONFIG_HUGETLB_PAGE is enabled, pageblock_order is not related to
> MAX_ORDER. I don't see HUGETLB_PAGE_ORDER is ensured to be less than
> section size. Maybe I missed it?
>
HUGETLB_PAGE_ORDER is less than MAX_ORDER on the basis that normal huge
pages (not gigantic) pages are served from the buddy allocator which is
limited by MAX_ORDER.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2018-12-05 15:37 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 9:19 [PATCH 1/2] mm, pageblock: make sure pageblock won't exceed mem_sectioin Wei Yang
2018-12-05 9:19 ` [PATCH 2/2] mm, page_alloc: cleanup usemap_size() when SPARSEMEM is not set Wei Yang
2018-12-07 9:58 ` Wei Yang
2018-12-05 11:15 ` [PATCH 1/2] mm, pageblock: make sure pageblock won't exceed mem_sectioin Mel Gorman
2018-12-05 12:08 ` Wei Yang
2018-12-05 15:37 ` Mel Gorman [this message]
2018-12-05 22:31 ` Wei Yang
2018-12-06 9:00 ` David Hildenbrand
2018-12-06 9:21 ` Wei Yang
2018-12-06 9:26 ` David Hildenbrand
2018-12-06 9:42 ` Wei Yang
2018-12-08 1:42 ` kbuild test robot
2018-12-09 12:03 ` Wei Yang
2018-12-13 2:26 ` Rong Chen
2018-12-13 3:08 ` Wei Yang
2018-12-13 5:02 ` Rong Chen
2018-12-13 7:28 ` Wei Yang
2018-12-09 13:58 ` kbuild test robot
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