From: Matthew Wilcox <willy@infradead.org>
To: Hugh Dickins <hughd@google.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>,
Alex Shi <alex.shi@linux.alibaba.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Tejun Heo <tj@kernel.org>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
Johannes Weiner <hannes@cmpxchg.org>,
kbuild test robot <lkp@intel.com>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
cgroups@vger.kernel.org, Shakeel Butt <shakeelb@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Wei Yang <richard.weiyang@gmail.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Rong Chen <rong.a.chen@intel.com>, Michal Hocko <mhocko@suse.com>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
shy828301@gmail.com,
Alexander Duyck <alexander.h.duyck@linux.intel.com>
Subject: Re: [PATCH v18 31/32] mm: Add explicit page decrement in exception path for isolate_lru_pages
Date: Wed, 9 Sep 2020 21:15:30 +0100 [thread overview]
Message-ID: <20200909201530.GM6583@casper.infradead.org> (raw)
In-Reply-To: <alpine.LSU.2.11.2009091100280.9020@eggly.anvils>
On Wed, Sep 09, 2020 at 11:24:14AM -0700, Hugh Dickins wrote:
> After overnight reflection, my own preference would be simply to
> drop this patch. I think we are making altogether too much of a
> fuss here over what was simply correct as plain put_page()
> (and further from correct if we change it to leak the page in an
> unforeseen circumstance).
>
> And if Alex's comment was not quite grammatically correct, never mind,
> it said as much as was worth saying. I got more worried by his
> placement of the "busy:" label, but that does appear to work correctly.
>
> There's probably a thousand places where put_page() is used, where
> it would be troublesome if it were the final put_page(): this one
> bothered you because you'd been looking at isolate_migratepages_block(),
> and its necessary avoidance of lru_lock recursion on put_page();
> but let's just just leave this put_page() as is.
My problem with put_page() is that it's no longer the simple
decrement-and-branch-to-slow-path-if-zero that it used to be. It has the
awful devmap excrement in it so it really expands into a lot of code.
I really wish that "feature" could be backed out again. It clearly
wasn't ready for merge.
next prev parent reply other threads:[~2020-09-09 20:16 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 12:54 [PATCH v18 00/32] per memcg lru_lock Alex Shi
2020-08-24 12:54 ` [PATCH v18 01/32] mm/memcg: warning on !memcg after readahead page charged Alex Shi
2020-08-24 12:54 ` [PATCH v18 02/32] mm/memcg: bail out early from swap accounting when memcg is disabled Alex Shi
2020-08-24 12:54 ` [PATCH v18 03/32] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-08-24 12:54 ` [PATCH v18 04/32] mm/thp: clean up lru_add_page_tail Alex Shi
2020-08-24 12:54 ` [PATCH v18 05/32] mm/thp: remove code path which never got into Alex Shi
2020-08-24 12:54 ` [PATCH v18 06/32] mm/thp: narrow lru locking Alex Shi
2020-09-10 13:49 ` Matthew Wilcox
2020-09-11 3:37 ` Alex Shi
2020-09-13 15:27 ` Matthew Wilcox
2020-09-19 1:00 ` Hugh Dickins
2020-08-24 12:54 ` [PATCH v18 07/32] mm/swap.c: stop deactivate_file_page if page not on lru Alex Shi
2020-08-24 12:54 ` [PATCH v18 08/32] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-08-24 12:54 ` [PATCH v18 09/32] mm/page_idle: no unlikely double check for idle page counting Alex Shi
2020-08-24 12:54 ` [PATCH v18 10/32] mm/compaction: rename compact_deferred as compact_should_defer Alex Shi
2020-08-24 12:54 ` [PATCH v18 11/32] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-08-24 12:54 ` [PATCH v18 12/32] mm/memcg: optimize mem_cgroup_page_lruvec Alex Shi
2020-08-24 12:54 ` [PATCH v18 13/32] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-08-24 12:54 ` [PATCH v18 14/32] mm/lru: move lru_lock holding in func lru_note_cost_page Alex Shi
2020-08-24 12:54 ` [PATCH v18 15/32] mm/lru: move lock into lru_note_cost Alex Shi
2020-09-21 21:36 ` Hugh Dickins
2020-09-21 22:03 ` Hugh Dickins
2020-09-22 3:39 ` Alex Shi
2020-09-22 3:38 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 16/32] mm/lru: introduce TestClearPageLRU Alex Shi
2020-09-21 23:16 ` Hugh Dickins
2020-09-22 3:53 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 17/32] mm/compaction: do page isolation first in compaction Alex Shi
2020-09-21 23:49 ` Hugh Dickins
2020-09-22 4:57 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 18/32] mm/thp: add tail pages into lru anyway in split_huge_page() Alex Shi
2020-08-24 12:54 ` [PATCH v18 19/32] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-09-22 0:42 ` Hugh Dickins
2020-09-22 5:00 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 20/32] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-09-22 5:27 ` Hugh Dickins
2020-09-22 8:58 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 21/32] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-09-22 5:40 ` Hugh Dickins
2020-08-24 12:54 ` [PATCH v18 22/32] mm/vmscan: use relock for move_pages_to_lru Alex Shi
2020-09-22 5:44 ` Hugh Dickins
2020-09-23 1:55 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 23/32] mm/lru: revise the comments of lru_lock Alex Shi
2020-09-22 5:48 ` Hugh Dickins
2020-08-24 12:54 ` [PATCH v18 24/32] mm/pgdat: remove pgdat lru_lock Alex Shi
2020-09-22 5:53 ` Hugh Dickins
2020-09-23 1:55 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page Alex Shi
2020-08-26 5:52 ` Alex Shi
2020-09-22 6:13 ` Hugh Dickins
2020-09-23 1:58 ` Alex Shi
2020-08-24 12:54 ` [PATCH v18 26/32] mm/mlock: remove __munlock_isolate_lru_page Alex Shi
2020-08-24 12:55 ` [PATCH v18 27/32] mm/swap.c: optimizing __pagevec_lru_add lru_lock Alex Shi
2020-08-26 9:07 ` Alex Shi
2020-08-24 12:55 ` [PATCH v18 28/32] mm/compaction: Drop locked from isolate_migratepages_block Alex Shi
2020-08-24 12:55 ` [PATCH v18 29/32] mm: Identify compound pages sooner in isolate_migratepages_block Alex Shi
2020-08-24 12:55 ` [PATCH v18 30/32] mm: Drop use of test_and_set_skip in favor of just setting skip Alex Shi
2020-08-24 12:55 ` [PATCH v18 31/32] mm: Add explicit page decrement in exception path for isolate_lru_pages Alex Shi
2020-09-09 1:01 ` Matthew Wilcox
2020-09-09 15:43 ` Alexander Duyck
2020-09-09 17:07 ` Matthew Wilcox
2020-09-09 18:24 ` Hugh Dickins
2020-09-09 20:15 ` Matthew Wilcox [this message]
2020-09-09 21:05 ` Hugh Dickins
2020-09-09 21:17 ` Alexander Duyck
2020-08-24 12:55 ` [PATCH v18 32/32] mm: Split release_pages work into 3 passes Alex Shi
2020-08-24 18:42 ` [PATCH v18 00/32] per memcg lru_lock Andrew Morton
2020-08-24 19:50 ` Qian Cai
2020-08-24 20:24 ` Hugh Dickins
2020-08-25 1:56 ` Daniel Jordan
2020-08-25 3:26 ` Alex Shi
2020-08-25 11:39 ` Matthew Wilcox
2020-08-26 1:19 ` Daniel Jordan
2020-08-26 8:59 ` Alex Shi
2020-08-28 1:40 ` Daniel Jordan
2020-08-28 5:22 ` Alex Shi
2020-09-09 2:44 ` Aaron Lu
2020-09-09 11:40 ` Michal Hocko
2020-08-25 8:52 ` Alex Shi
2020-08-25 13:00 ` Alex Shi
2020-08-27 7:01 ` Hugh Dickins
2020-08-27 12:20 ` Race between freeing and waking page Matthew Wilcox
2020-09-08 23:41 ` [PATCH v18 00/32] per memcg lru_lock: reviews Hugh Dickins
2020-09-09 2:24 ` Wei Yang
2020-09-09 15:08 ` Alex Shi
2020-09-09 23:16 ` Hugh Dickins
2020-09-11 2:50 ` Alex Shi
2020-09-12 2:13 ` Hugh Dickins
2020-09-13 14:21 ` Alex Shi
2020-09-15 8:21 ` Hugh Dickins
2020-09-15 16:58 ` Daniel Jordan
2020-09-17 2:37 ` Alex Shi
2020-09-17 14:35 ` Daniel Jordan
2020-09-17 15:39 ` Alexander Duyck
2020-09-17 16:48 ` Daniel Jordan
2020-09-12 8:38 ` Hugh Dickins
2020-09-13 14:22 ` Alex Shi
2020-09-09 16:11 ` Alexander Duyck
2020-09-10 0:32 ` Hugh Dickins
2020-09-10 14:24 ` Alexander Duyck
2020-09-12 5:12 ` Hugh Dickins
2020-08-25 7:21 ` [PATCH v18 00/32] per memcg lru_lock Michal Hocko
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