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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: "Maya B . Gokhale" <gokhale2@llnl.gov>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Yang Shi <yang.shi@linux.alibaba.com>,
	Marty Mcfadden <mcfadden8@llnl.gov>,
	peterx@redhat.com, Kirill Shutemov <kirill@shutemov.name>,
	Oleg Nesterov <oleg@redhat.com>, Jann Horn <jannh@google.com>,
	Jan Kara <jack@suse.cz>, Kirill Tkhai <ktkhai@virtuozzo.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 0/4] mm: Simplfy cow handling
Date: Fri, 21 Aug 2020 19:49:54 -0400
Message-ID: <20200821234958.7896-1-peterx@redhat.com> (raw)

This is a small series that I picked up from Linus's suggestion [0] to simplify\r
cow handling (and also more strict) by checking against page refcounts rather\r
than mapcounts.\r
\r
I'm CCing the author and reviewer of commit 52d1e606ee73 on ksm ("mm: reuse\r
only-pte-mapped KSM page in do_wp_page()", 2019-03-05).  Please shoot if\r
there's any reason to keep the logic, or it'll be removed in this series.  For\r
more information, please refer to [3,4].\r
\r
The new mm counter in the last patch can be seen as RFC, depending on whether\r
anyone dislikes it... I used it majorly for observing the page reuses, so it is\r
kind of optional.\r
\r
Two tests I did:\r
\r
  - Run a busy loop dirty program [1] that uses 6G of memory, restrict to 1G\r
    RAM + 5G swap (cgroup).  A few hours later, all things still look good.\r
    Make sure to observe (still massive) correct page reuses using the new\r
    counter using the last patch, probably when swapping in.\r
\r
  - Run umapsort [2] to make sure uffd-wp will work again after applying this\r
    series upon master 5.9-rc1 (5.9-rc1 is broken).\r
\r
In all cases, I must confess it's quite pleased to post a series with diffstat\r
like this...  Hopefully this won't break anyone but only to make everything\r
better.\r
\r
Please review, thanks.\r
\r
[0] https://lore.kernel.org/lkml/CAHk-=wjn90-=s6MBerxTuP=-FVEZtR-LpoH9eenEQ3A-QfKTZw@mail.gmail.com\r
[1] https://github.com/xzpeter/clibs/blob/master/bsd/mig_mon/mig_mon.c\r
[2] https://github.com/LLNL/umap-apps/blob/develop/src/umapsort/umapsort.cpp\r
[3] https://lore.kernel.org/lkml/CAHk-=wh0syDtNzt9jGyHRV0r1pVX5gkdJWdenwmvy=dq0AL5mA@mail.gmail.com\r
[4] https://lore.kernel.org/lkml/CAHk-=wj5Oyg0LeAxSw_vizerm=sLd=sHfcVecZMKPZn6kNbbXA@mail.gmail.com\r
\r
Linus Torvalds (1):\r
  mm: Trial do_wp_page() simplification\r
\r
Peter Xu (3):\r
  mm/ksm: Remove reuse_ksm_page()\r
  mm/gup: Remove enfornced COW mechanism\r
  mm: Add PGREUSE counter\r
\r
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c |  8 ---\r
 include/linux/ksm.h                         |  7 ---\r
 include/linux/vm_event_item.h               |  1 +\r
 mm/gup.c                                    | 40 ++------------\r
 mm/huge_memory.c                            |  7 +--\r
 mm/ksm.c                                    | 25 ---------\r
 mm/memory.c                                 | 60 +++++++--------------\r
 mm/vmstat.c                                 |  1 +\r
 8 files changed, 29 insertions(+), 120 deletions(-)\r
\r
-- \r
2.26.2\r
\r


             reply index

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-21 23:49 Peter Xu [this message]
2020-08-21 23:49 ` [PATCH 1/4] mm: Trial do_wp_page() simplification Peter Xu
2020-08-24  8:36   ` Kirill Tkhai
2020-08-24 14:30     ` Jan Kara
2020-08-24 15:37       ` Kirill Tkhai
2020-08-24 18:22         ` Linus Torvalds
2020-09-01  7:01           ` Hugh Dickins
2020-09-14 14:38   ` Jason Gunthorpe
2020-09-14 17:32     ` Linus Torvalds
2020-09-14 18:34       ` Peter Xu
2020-09-14 21:15         ` Peter Xu
2020-09-14 22:55           ` Jason Gunthorpe
2020-09-14 22:59             ` Linus Torvalds
2020-09-14 23:28               ` Jason Gunthorpe
2020-09-15  0:19                 ` Linus Torvalds
2020-09-15 14:50                 ` Peter Xu
2020-09-15 15:17                   ` Peter Xu
2020-09-15 16:05                   ` Jason Gunthorpe
2020-09-15 18:29                     ` Jason Gunthorpe
2020-09-15 19:13                       ` Peter Xu
2020-09-15 19:38                         ` Jason Gunthorpe
2020-09-15 21:33                           ` Peter Xu
2020-09-15 23:22                             ` Jason Gunthorpe
2020-09-16  1:50                               ` John Hubbard
2020-09-16 17:48                                 ` Jason Gunthorpe
2020-09-16 18:46                                   ` Peter Xu
2020-09-17 11:25                                     ` Jason Gunthorpe
2020-09-17 18:11                                       ` Linus Torvalds
2020-09-17 19:38                                         ` Jason Gunthorpe
2020-09-17 19:51                                           ` Linus Torvalds
2020-09-18 16:40                                             ` Peter Xu
2020-09-18 17:16                                               ` Linus Torvalds
2020-09-18 19:57                                                 ` Peter Xu
2020-09-18 17:32                                               ` Jason Gunthorpe
2020-09-18 20:40                                                 ` Peter Xu
2020-09-18 20:59                                                   ` Linus Torvalds
2020-09-19  0:28                                                     ` Jason Gunthorpe
2020-09-18 21:06                                                   ` John Hubbard
2020-09-19  0:01                                                     ` Jason Gunthorpe
2020-09-21  8:35                                                       ` Jan Kara
2020-09-21 12:03                                                         ` Jason Gunthorpe
2020-09-21 13:42                                               ` Michal Hocko
2020-09-21 14:18                                                 ` Peter Xu
2020-09-21 14:28                                                   ` Michal Hocko
2020-09-21 14:38                                                     ` Tejun Heo
2020-09-21 14:43                                                       ` Christian Brauner
2020-09-21 14:55                                                         ` Michal Hocko
2020-09-21 15:04                                                           ` Christian Brauner
2020-09-21 16:06                                                             ` Michal Hocko
2020-09-23  7:53                                                               ` Michal Hocko
2020-09-21 14:41                                                 ` Christian Brauner
2020-09-21 14:57                                                   ` Michal Hocko
2020-09-21 16:31                                                     ` Peter Xu
2020-09-17 18:14                                       ` Peter Xu
2020-09-17 18:26                                         ` Linus Torvalds
2020-09-17 19:03                                           ` Peter Xu
2020-09-17 19:42                                             ` Linus Torvalds
2020-09-17 19:55                                               ` John Hubbard
2020-09-17 20:06                                               ` Jason Gunthorpe
2020-09-17 20:19                                                 ` John Hubbard
2020-09-17 20:25                                                   ` Jason Gunthorpe
2020-09-17 20:35                                                 ` Linus Torvalds
2020-09-17 21:40                                                   ` Peter Xu
2020-09-17 22:09                                                     ` Jason Gunthorpe
2020-09-17 22:25                                                       ` Linus Torvalds
2020-09-17 22:48                                                       ` Ira Weiny
2020-09-18  9:36                                                         ` Jan Kara
2020-09-18  9:44                                                       ` Jan Kara
2020-09-18 16:19                                             ` Jason Gunthorpe
2020-09-15 10:23           ` Leon Romanovsky
2020-09-15 15:56           ` Jason Gunthorpe
2020-09-15 15:03   ` Oleg Nesterov
2020-09-15 16:18     ` Peter Xu
2020-08-21 23:49 ` [PATCH 2/4] mm/ksm: Remove reuse_ksm_page() Peter Xu
2020-08-21 23:49 ` [PATCH 3/4] mm/gup: Remove enfornced COW mechanism Peter Xu
2020-09-14 14:27   ` Oleg Nesterov
2020-09-14 17:59     ` Peter Xu
2020-09-14 19:03       ` Linus Torvalds
2020-08-21 23:49 ` [PATCH 4/4] mm: Add PGREUSE counter Peter Xu
2020-08-22 16:14   ` Linus Torvalds
2020-08-24  0:24     ` Peter Xu
2020-08-22 16:05 ` [PATCH 0/4] mm: Simplfy cow handling Linus Torvalds
2020-08-23 23:58   ` Peter Xu
2020-08-24  8:38 ` Kirill Tkhai
2020-08-27 14:15 ` Peter Xu

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