From: Michal Hocko <mhocko@kernel.org>
To: Frank Mehnert <frank.mehnert@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: PG_reserved and compound pages
Date: Wed, 6 Apr 2016 17:02:06 +0200 [thread overview]
Message-ID: <20160406150206.GB24283@dhcp22.suse.cz> (raw)
In-Reply-To: <4482994.u2S3pScRyb@noys2>
[CCing linux-mm mailing list]
On Wed 06-04-16 13:28:37, Frank Mehnert wrote:
> Hi,
>
> Linux 4.5 introduced additional checks to ensure that compound pages are
> never marked as reserved. In our code we use PG_reserved to ensure that
> the kernel does never swap out such pages, e.g.
Are you putting your pages on the LRU list? If not how they could get
swapped out?
>
> int i;
> struct page *pages = alloc_pages(GFP_HIGHUSER | __GFP_COMP, 4);
> for (i = 0; i < 16; i++)
> SetPageReserved(&pages[i]);
>
> The purpose of setting PG_reserved is to prevent the kernel from swapping
> this memory out. This worked with older kernel but not with Linux 4.5 as
> setting PG_reserved to compound pages is not allowed any more.
>
> Can somebody explain how we can achieve the same result in accordance to
> the new Linux 4.5 rules?
>
> Thanks,
>
> Frank
--
Michal Hocko
SUSE Labs
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next parent reply other threads:[~2016-04-06 15:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4482994.u2S3pScRyb@noys2>
2016-04-06 15:02 ` Michal Hocko [this message]
2016-04-06 15:12 ` Frank Mehnert
2016-04-06 15:33 ` Michal Hocko
2016-04-07 13:45 ` Frank Mehnert
2016-04-07 15:22 ` Michal Hocko
2016-04-19 10:34 ` Frank Mehnert
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