From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Jason Baron <jbaron@akamai.com>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Mel Gorman <mgorman@suse.de>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linux-api@vger.kernel.org, emunson@mgebm.net
Subject: Re: [PATCH] mm/madvise: allow MADV_DONTNEED to free memory that is MLOCK_ONFAULT
Date: Wed, 13 Jun 2018 10:37:07 +0200 [thread overview]
Message-ID: <20180613083707.GE13364@dhcp22.suse.cz> (raw)
In-Reply-To: <5eb9a018-d5ac-5732-04f1-222c343b840a@suse.cz>
On Wed 13-06-18 09:51:23, Vlastimil Babka wrote:
> On 06/13/2018 09:15 AM, Michal Hocko wrote:
> > On Wed 13-06-18 08:32:19, Vlastimil Babka wrote:
[...]
> >> I think more concerning than guaranteeing no later major fault is
> >> possible data loss, e.g. replacing data with zero-filled pages.
> >
> > But MADV_DONTNEED is an explicit call for data loss. Or do I miss your
> > point?
>
> My point is that if somebody is relying on MADV_DONTNEED not affecting
> mlocked pages, the consequences will be unexpected data loss, not just
> extra page faults.
OK, I see your point now. I would consider this an application bug
though. Calling MADV_DONTNEED and wondering that the content is gone is,
ehm, questionable at best. Why would anybody do that in the first place?
Anyway, I think that we cannot change the behavior because of mlockall
semantic as mentioned earlier.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-06-13 8:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-08 18:56 Jason Baron
2018-06-08 19:57 ` Andrew Morton
2018-06-08 20:55 ` Jason Baron
2018-06-09 11:51 ` kbuild test robot
2018-06-11 7:20 ` Michal Hocko
2018-06-11 14:51 ` Jason Baron
2018-06-11 15:03 ` Michal Hocko
2018-06-11 16:23 ` Jason Baron
2018-06-12 7:46 ` Michal Hocko
2018-06-12 14:11 ` Jason Baron
2018-06-13 6:32 ` Vlastimil Babka
2018-06-13 7:15 ` Michal Hocko
2018-06-13 7:51 ` Vlastimil Babka
2018-06-13 8:37 ` Michal Hocko [this message]
2018-06-15 19:36 ` Jason Baron
2018-06-20 11:00 ` Michal Hocko
2018-06-28 20:20 ` Jason Baron
2018-06-13 9:13 ` Michal Hocko
2018-06-15 19:28 ` Jason Baron
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