From: Michal Hocko <mhocko@kernel.org>
To: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <richard.weiyang@gmail.com>,
akpm@linux-foundation.org, vbabka@suse.cz,
pavel.tatashin@microsoft.com, rppt@linux.vnet.ibm.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm, page_alloc: Fix has_unmovable_pages for HugePages
Date: Thu, 20 Dec 2018 10:12:28 +0100 [thread overview]
Message-ID: <20181220091228.GB14234@dhcp22.suse.cz> (raw)
In-Reply-To: <20181219233914.2fxe26pih26ifvmt@d104.suse.de>
On Thu 20-12-18 00:39:18, Oscar Salvador wrote:
> On Wed, Dec 19, 2018 at 02:25:28PM +0000, Wei Yang wrote:
> > >- iter = round_up(iter + 1, 1<<compound_order(page)) - 1;
> > >+ skip_pages = (1 << compound_order(head)) - (page - head);
> > >+ iter = round_up(iter + 1, skip_pages) - 1;
> >
> > The comment of round_up says round up to next specified power of 2. And
> > second parameter must be a power of 2.
> >
> > Look skip_pages not satisfy this.
Yes this is true but the resulting numbers should be correct even for
skips that are not power of 2 AFAIC. Or do you have any counter example?
>
> At least alloc_gigantic_page() looks for 1GB range, aligned to that.
> But I see that in alloc_contig_range(), the boundaries can differ.
>
> Anyway, unless I am missing something, I think that we could just
> get rid of the round_up() and do something like:
>
> <--
> skip_pages = (1 << compound_order(head)) - (page - head);
> iter = skip_pages - 1;
> --
>
> which looks more simple IMHO.
Agreed!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-12-20 9:12 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-17 22:51 [PATCH v2] mm, page_alloc: Fix has_unmovable_pages for HugePages Oscar Salvador
2018-12-17 23:07 ` Andrew Morton
2018-12-18 7:36 ` Michal Hocko
2018-12-18 21:46 ` Andrew Morton
2018-12-18 21:51 ` Oscar Salvador
2018-12-19 14:25 ` Wei Yang
2018-12-19 14:28 ` Wei Yang
2018-12-19 23:39 ` Oscar Salvador
2018-12-20 9:12 ` Michal Hocko [this message]
2018-12-20 12:49 ` Oscar Salvador
2018-12-20 13:06 ` Michal Hocko
2018-12-20 13:41 ` Oscar Salvador
2018-12-20 14:21 ` Oscar Salvador
2018-12-20 14:39 ` Michal Hocko
2018-12-20 15:37 ` Oscar Salvador
2018-12-20 15:32 ` Wei Yang
2018-12-20 15:32 ` Wei Yang
2018-12-20 15:52 ` Oscar Salvador
2018-12-20 13:08 ` Wei Yang
2018-12-20 13:49 ` Oscar Salvador
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