From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Jerome Marchand <jmarchan@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>,
Dave Hansen <dave.hansen@intel.com>, Mel Gorman <mgorman@suse.de>,
Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
Christoph Lameter <cl@gentwo.org>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Steve Capper <steve.capper@linaro.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>,
Sasha Levin <sasha.levin@oracle.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCHv6 00/36] THP refcounting redesign
Date: Mon, 22 Jun 2015 16:21:25 +0300 [thread overview]
Message-ID: <20150622132125.GG7934@node.dhcp.inet.fi> (raw)
In-Reply-To: <558021D9.4050304@redhat.com>
On Tue, Jun 16, 2015 at 03:17:13PM +0200, Jerome Marchand wrote:
> On 06/03/2015 07:05 PM, Kirill A. Shutemov wrote:
> > Hello everybody,
> >
> > Here's new revision of refcounting patchset. Please review and consider
> > applying.
> >
> > The goal of patchset is to make refcounting on THP pages cheaper with
> > simpler semantics and allow the same THP compound page to be mapped with
> > PMD and PTEs. This is required to get reasonable THP-pagecache
> > implementation.
> >
> > With the new refcounting design it's much easier to protect against
> > split_huge_page(): simple reference on a page will make you the deal.
> > It makes gup_fast() implementation simpler and doesn't require
> > special-case in futex code to handle tail THP pages.
> >
> > It should improve THP utilization over the system since splitting THP in
> > one process doesn't necessary lead to splitting the page in all other
> > processes have the page mapped.
> >
> > The patchset drastically lower complexity of get_page()/put_page()
> > codepaths. I encourage people look on this code before-and-after to
> > justify time budget on reviewing this patchset.
> >
> > = Changelog =
> >
> > v6:
> > - rebase to since-4.0;
> > - optimize mapcount handling: significantely reduce overhead for most
> > common cases.
> > - split pages on migrate_pages();
> > - remove infrastructure for handling splitting PMDs on all architectures;
> > - fix page_mapcount() for hugetlb pages;
> >
>
> Hi Kirill,
>
> I ran some LTP mm tests and hugemmap tests trigger the following:
>
> [ 438.749457] page:ffffea0000df8000 count:2 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0
> [ 438.750089] flags: 0x3ffc0000004001(locked|head)
> [ 438.750089] page dumped because: VM_BUG_ON_PAGE(page_mapped(page))
Did you run with original or updated version of patch 27/36?
In original post of v6 there was bug: page_mapped() always returned true.
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2015-06-22 13:22 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-03 17:05 [PATCHv6 00/36] THP refcounting redesign Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 01/36] mm, proc: adjust PSS calculation Kirill A. Shutemov
2015-06-09 12:29 ` Vlastimil Babka
2015-06-22 10:02 ` Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 02/36] rmap: add argument to charge compound page Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 03/36] memcg: adjust to support new THP refcounting Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 04/36] mm, thp: adjust conditions when we can reuse the page on WP fault Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 05/36] mm: adjust FOLL_SPLIT for new refcounting Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 06/36] mm: handle PTE-mapped tail pages in gerneric fast gup implementaiton Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 07/36] thp, mlock: do not allow huge pages in mlocked area Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 08/36] khugepaged: ignore pmd tables with THP mapped with ptes Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 09/36] thp: rename split_huge_page_pmd() to split_huge_pmd() Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 10/36] mm, vmstats: new THP splitting event Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 11/36] mm: temporally mark THP broken Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 12/36] thp: drop all split_huge_page()-related code Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 13/36] mm: drop tail page refcounting Kirill A. Shutemov
2015-06-09 13:59 ` Vlastimil Babka
2015-06-03 17:05 ` [PATCHv6 14/36] futex, thp: remove special case for THP in get_futex_key Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 15/36] ksm: prepare to new THP semantics Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 16/36] mm, thp: remove compound_lock Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 17/36] arm64, thp: remove infrastructure for handling splitting PMDs Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 18/36] arm, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 19/36] mips, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 20/36] powerpc, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 21/36] s390, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 22/36] sparc, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 23/36] tile, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 24/36] x86, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 25/36] mm, " Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 26/36] mm: rework mapcount accounting to enable 4k mapping of THPs Kirill A. Shutemov
2015-06-10 13:47 ` Vlastimil Babka
2015-06-22 10:22 ` Kirill A. Shutemov
2015-06-03 17:05 ` [PATCHv6 27/36] mm: differentiate page_mapped() from page_mapcount() for compound pages Kirill A. Shutemov
2015-06-09 10:58 ` Kirill A. Shutemov
2015-06-10 14:34 ` Vlastimil Babka
2015-06-03 17:05 ` [PATCHv6 28/36] mm, numa: skip PTE-mapped THP on numa fault Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 29/36] thp: implement split_huge_pmd() Kirill A. Shutemov
2015-06-11 9:49 ` Vlastimil Babka
2015-06-22 11:14 ` Kirill A. Shutemov
2015-06-22 16:01 ` Vlastimil Babka
2015-06-03 17:06 ` [PATCHv6 30/36] thp: add option to setup migration entiries during PMD split Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 31/36] thp, mm: split_huge_page(): caller need to lock page Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 32/36] thp: reintroduce split_huge_page() Kirill A. Shutemov
2015-06-10 15:44 ` Vlastimil Babka
2015-06-22 11:28 ` Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 33/36] migrate_pages: try to split pages on qeueuing Kirill A. Shutemov
2015-06-11 9:27 ` Vlastimil Babka
2015-06-22 11:35 ` Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 34/36] thp: introduce deferred_split_huge_page() Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 35/36] mm: re-enable THP Kirill A. Shutemov
2015-06-03 17:06 ` [PATCHv6 36/36] thp: update documentation Kirill A. Shutemov
2015-06-11 12:30 ` Vlastimil Babka
2015-06-22 13:18 ` Kirill A. Shutemov
2015-06-22 16:07 ` Vlastimil Babka
2015-06-16 13:17 ` [PATCHv6 00/36] THP refcounting redesign Jerome Marchand
2015-06-22 13:21 ` Kirill A. Shutemov [this message]
2015-06-22 13:32 ` Jerome Marchand
2015-06-22 13:39 ` Kirill A. Shutemov
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