From: "Huang\, Ying" <ying.huang@intel.com>
To: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shaohua Li <shli@kernel.org>, Hugh Dickins <hughd@google.com>,
Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Zi Yan <zi.yan@cs.rutgers.edu>
Subject: Re: [PATCH -mm -v4 14/21] mm, cgroup, THP, swap: Support to move swap account for PMD swap mapping
Date: Tue, 10 Jul 2018 15:49:58 +0800 [thread overview]
Message-ID: <87tvp7h6mx.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <20180709172037.254zyuadep2hj5po@ca-dmjordan1.us.oracle.com> (Daniel Jordan's message of "Mon, 9 Jul 2018 10:20:37 -0700")
Daniel Jordan <daniel.m.jordan@oracle.com> writes:
> On Fri, Jun 22, 2018 at 11:51:44AM +0800, Huang, Ying wrote:
>> Because there is no way to prevent a huge swap cluster from being
>> split except when it has SWAP_HAS_CACHE flag set.
>
> What about making get_mctgt_type_thp take the cluster lock? That function
> would be the first lock_cluster user outside of swapfile.c, but it would
> serialize with split_swap_cluster.
>
>> It is possible for
>> the huge swap cluster to be split and the charge for the swap slots
>> inside to be changed, after we check the PMD swap mapping and the huge
>> swap cluster before we commit the charge moving. But the race window
>> is so small, that we will just ignore the race.
>
> Moving the charges is a slow path, so can't we just be correct here and not
> leak?
Check the code and thought about this again, found the race may not
exist. Because the PMD is locked when get_mctgt_type_thp() is called
until charge is completed for the PMD. So the charge of the huge swap
cluster cannot be changed at the same time even if the huge swap cluster
is split by other processes. Right?
Will update the comments for this.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2018-07-10 7:50 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-22 3:51 [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one piece Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 01/21] mm, THP, swap: Enable PMD swap operations for CONFIG_THP_SWAP Huang, Ying
2018-07-07 21:11 ` Dan Williams
2018-07-09 5:40 ` Huang, Ying
2018-07-09 6:08 ` Dan Williams
2018-07-09 6:34 ` Huang, Ying
2018-07-09 15:59 ` Dave Hansen
2018-07-10 1:08 ` Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 02/21] mm, THP, swap: Make CONFIG_THP_SWAP depends on CONFIG_SWAP Huang, Ying
2018-07-07 21:12 ` Dan Williams
2018-07-09 6:34 ` Huang, Ying
2018-07-09 16:00 ` Dave Hansen
2018-07-10 1:19 ` Huang, Ying
2018-07-10 1:59 ` Dave Hansen
2018-07-10 5:26 ` Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 03/21] mm, THP, swap: Support PMD swap mapping in swap_duplicate() Huang, Ying
2018-06-29 6:04 ` Matthew Wilcox
2018-07-02 5:19 ` Huang, Ying
2018-07-07 23:22 ` Dan Williams
2018-07-09 7:38 ` Huang, Ying
2018-07-09 16:51 ` Dave Hansen
2018-07-10 6:44 ` Huang, Ying
2018-07-10 13:50 ` Dave Hansen
2018-07-11 0:59 ` Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 04/21] mm, THP, swap: Support PMD swap mapping in swapcache_free_cluster() Huang, Ying
2018-07-09 17:11 ` Dave Hansen
2018-07-10 6:53 ` Huang, Ying
2018-07-10 13:54 ` Dave Hansen
2018-07-11 1:08 ` Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 05/21] mm, THP, swap: Support PMD swap mapping in free_swap_and_cache()/swap_free() Huang, Ying
2018-07-05 18:33 ` Daniel Jordan
2018-07-06 12:49 ` Huang, Ying
2018-07-09 17:19 ` Dave Hansen
2018-07-10 7:13 ` Huang, Ying
2018-07-10 14:07 ` Dave Hansen
2018-07-11 1:28 ` Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 06/21] mm, THP, swap: Support PMD swap mapping when splitting huge PMD Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 07/21] mm, THP, swap: Support PMD swap mapping in split_swap_cluster() Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 08/21] mm, THP, swap: Support to read a huge swap cluster for swapin a THP Huang, Ying
2018-06-29 6:21 ` Matthew Wilcox
2018-07-02 6:02 ` Huang, Ying
2018-07-04 0:12 ` Daniel Jordan
2018-07-04 2:24 ` Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 09/21] mm, THP, swap: Swapin a THP as a whole Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 10/21] mm, THP, swap: Support to count THP swapin and its fallback Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 11/21] mm, THP, swap: Add sysfs interface to configure THP swapin Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 12/21] mm, THP, swap: Support PMD swap mapping in swapoff Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 13/21] mm, THP, swap: Support PMD swap mapping in madvise_free() Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 14/21] mm, cgroup, THP, swap: Support to move swap account for PMD swap mapping Huang, Ying
2018-07-09 17:20 ` Daniel Jordan
2018-07-10 7:49 ` Huang, Ying [this message]
2018-07-10 22:49 ` Daniel Jordan
2018-06-22 3:51 ` [PATCH -mm -v4 15/21] mm, THP, swap: Support to copy PMD swap mapping when fork() Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 16/21] mm, THP, swap: Free PMD swap mapping when zap_huge_pmd() Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 17/21] mm, THP, swap: Support PMD swap mapping for MADV_WILLNEED Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 18/21] mm, THP, swap: Support PMD swap mapping in mincore() Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 19/21] mm, THP, swap: Support PMD swap mapping in common path Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 20/21] mm, THP, swap: create PMD swap mapping when unmap the THP Huang, Ying
2018-06-22 3:51 ` [PATCH -mm -v4 21/21] mm, THP: Avoid to split THP when reclaim MADV_FREE THP Huang, Ying
2018-06-28 4:51 ` [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one piece Andrew Morton
2018-06-28 5:29 ` Huang, Ying
2018-06-28 5:31 ` Andrew Morton
2018-06-28 5:35 ` Huang, Ying
2018-06-28 6:18 ` Andrew Morton
2018-06-28 9:03 ` Matthew Wilcox
2018-06-29 1:17 ` Huang, Ying
2018-06-29 5:57 ` Matthew Wilcox
2018-07-02 5:19 ` Huang, Ying
2018-07-04 2:11 ` Sergey Senozhatsky
2018-07-04 2:20 ` Huang, Ying
2018-07-04 2:27 ` Sergey Senozhatsky
2018-07-04 2:59 ` Huang, Ying
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