linux-kernel - Re: mm: pages are not freed from lru_add

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Message-ID: <572776EF.2070804@intel.com>
Date:	Mon, 2 May 2016 08:49:03 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	"Kirill A. Shutemov" <kirill@...temov.name>,
	Vlastimil Babka <vbabka@...e.cz>
Cc:	"Odzioba, Lukasz" <lukasz.odzioba@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"Shutemov, Kirill" <kirill.shutemov@...el.com>,
	"Anaczkowski, Lukasz" <lukasz.anaczkowski@...el.com>
Subject: Re: mm: pages are not freed from lru_add_pvecs after process
 termination

On 05/02/2016 08:01 AM, Kirill A. Shutemov wrote:
> On Mon, May 02, 2016 at 04:39:35PM +0200, Vlastimil Babka wrote:
>> On 04/27/2016 07:11 PM, Dave Hansen wrote:
>>> 6. Perhaps don't use the LRU pagevecs for large pages.  It limits the
>>>    severity of the problem.
>>
>> I think that makes sense. Being large already amortizes the cost per base
>> page much more than pagevecs do (512 vs ~22 pages?).
> 
> We try to do this already, don't we? Any spefic case where we have THPs on
> pagevecs?

Lukas was hitting this on a RHEL 7 era kernel.  In his kernel at least,
I'm pretty sure THP's were ending up on pagevecs.  Are you saying you
don't think we're doing that any more?