From: Benjamin LaHaise <bcrl@kvack•org>
To: Oleg Nesterov <oleg@redhat•com>
Cc: Jeff Moyer <jmoyer@redhat•com>,
Andrew Morton <akpm@linux-foundation•org>,
Joonsoo Kim <js1304@gmail•com>,
Fengguang Wu <fengguang.wu@intel•com>,
Johannes Weiner <hannes@cmpxchg•org>,
Stephen Rothwell <sfr@canb•auug.org.au>,
linux-next@vger•kernel.org, linux-kernel@vger•kernel.org
Subject: Re: [PATCH] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix
Date: Mon, 20 Jul 2015 15:39:12 -0400 [thread overview]
Message-ID: <20150720193912.GJ21558@kvack.org> (raw)
In-Reply-To: <20150720192440.GA20573@redhat.com>
On Mon, Jul 20, 2015 at 09:24:40PM +0200, Oleg Nesterov wrote:
> On 07/20, Oleg Nesterov wrote:
> >
> > But again, again, please ignore. This all is off-topic and my understanding
> > is very limited.
>
> Yes, yes, but sorry for noise and let me repeat...
>
> This memory lives in page-cache/lru, it is visible for shrinker which
> will unmap these pages for no reason on memory shortage. IOW, aio fools
> the kernel, this memory looks reclaimable but it is not. And we only do
> this for migration.
And we have the same problem with O_DIRECT. Given the size of the LRU in
a modern system, I highly doubt a handful of pages getting scanned is a
major problem. If you want to improve this, go ahead, but we need to
retain support for page migration as people have run into the need for it.
> Even if this is not a problem, this does not look right. So perhaps at
> least mapping_set_unevictable() makes sense. But I simply do not know
> if migration will work with this change.
Nor do I know if that will work.
> And I should have changes the subject a long ago... So what do you think
> we should do with the build failure?
I honestly don't care what of the options you do -- please just don't go
about adding BUG()s.
-ben
> Oleg.
--
"Thought is the essence of where you are now."
next prev parent reply other threads:[~2015-07-20 19:39 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-16 23:14 [PATCH] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix Oleg Nesterov
2015-07-16 23:22 ` Stephen Rothwell
2015-07-16 23:24 ` Andrew Morton
2015-07-16 23:52 ` Oleg Nesterov
2015-07-17 14:06 ` Benjamin LaHaise
2015-07-17 17:27 ` Oleg Nesterov
2015-07-17 17:37 ` Benjamin LaHaise
2015-07-17 17:55 ` Oleg Nesterov
2015-07-17 18:12 ` Austin S Hemmelgarn
2015-07-17 18:19 ` Oleg Nesterov
2015-07-17 18:39 ` Austin S Hemmelgarn
2015-07-17 18:54 ` Oleg Nesterov
2015-07-17 19:09 ` Austin S Hemmelgarn
2015-07-17 22:56 ` Oleg Nesterov
2015-07-17 22:31 ` Oleg Nesterov
2015-07-20 14:22 ` Jeff Moyer
2015-07-20 17:33 ` Oleg Nesterov
2015-07-20 17:51 ` Benjamin LaHaise
2015-07-20 18:30 ` Jeff Moyer
2015-07-20 18:31 ` Oleg Nesterov
2015-07-20 19:24 ` Oleg Nesterov
2015-07-20 19:39 ` Benjamin LaHaise [this message]
2015-07-20 20:03 ` Oleg Nesterov
2015-07-21 15:29 ` [PATCH v2] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix Oleg Nesterov
2015-07-21 15:38 ` Benjamin LaHaise
2015-07-21 16:18 ` Oleg Nesterov
2015-07-21 16:20 ` [PATCH v3] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix Oleg Nesterov
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