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: Re: PG_reserved and compound pages
Date: Wed, 6 Apr 2016 17:33:43 +0200 [thread overview]
Message-ID: <20160406153343.GJ24272@dhcp22.suse.cz> (raw)
In-Reply-To: <3877205.TjDYue2aah@noys2>
On Wed 06-04-16 17:12:43, Frank Mehnert wrote:
> Hi Michal,
>
> On Wednesday 06 April 2016 17:02:06 Michal Hocko wrote:
> > [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?
>
> No, we do nothing like that. It was my understanding that at least with
> older kernels it was possible that pages allocated with alloc_pages()
> could be swapped out or otherwise manipulated, I might be wrong.
I do not see anything like that. All the evictable pages should be on
a LRU.
> For
> instance, it's also necessary that the physical address of the page
> is known and that it does never change. I know, there might be problems
> with automatic NUMA page migration but that's another story.
Do you map your pages to the userspace? If yes then vma with VM_IO or
VM_PFNMAP should keep any attempt away from those pages.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-04-06 15:33 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
2016-04-06 15:12 ` Frank Mehnert
2016-04-06 15:33 ` Michal Hocko [this message]
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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