From: Johannes Weiner <hannes@cmpxchg.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, cgroups@vger.kernel.org,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [PATCH v3 13/18] mm/memcg: Add folio_memcg_lock() and folio_memcg_unlock()
Date: Wed, 7 Jul 2021 16:41:05 -0400 [thread overview]
Message-ID: <YOYRYXATm2gHoGGq@cmpxchg.org> (raw)
In-Reply-To: <YOYAZ5+xDFK0Slc8@casper.infradead.org>
On Wed, Jul 07, 2021 at 08:28:39PM +0100, Matthew Wilcox wrote:
> On Wed, Jul 07, 2021 at 01:08:51PM -0400, Johannes Weiner wrote:
> > On Wed, Jun 30, 2021 at 05:00:29AM +0100, Matthew Wilcox (Oracle) wrote:
> > > -static void __unlock_page_memcg(struct mem_cgroup *memcg)
> > > +static void __memcg_unlock(struct mem_cgroup *memcg)
> >
> > This is too generic a name. There are several locks in the memcg, and
> > this one only locks the page->memcg bindings in the group.
>
> Fair. __memcg_move_unlock looks like the right name to me?
Could you please elaborate what the problem with the current name is?
mem_cgroup_move_account() does this:
lock_page_memcg(page);
page->memcg = to;
__unlock_page_memcg(from);
It locks and unlocks the page->memcg binding which can be done coming
from the page or the memcg. The current names are symmetrical to
reflect that it's the same lock.
We could switch them both to move_lock, but as per the other email,
lock_page_memcg() was chosen to resemble lock_page(). Because from a
memcg POV they're interchangeable - the former is just a more narrowly
scoped version for contexts that don't hold the page lock. It used to
be called something else and we had several contexts taking redundant
locks on accident because this hierarchy wasn't clear.
I don't mind fixing poorly chosen or misleading naming schemes, but I
think we need better explanations to overcome the reasoning behind the
existing names, not just the assumption that there weren't any.
next prev parent reply other threads:[~2021-07-07 20:41 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-30 4:00 [PATCH v3 00/18] Folio conversion of memcg Matthew Wilcox (Oracle)
2021-06-30 4:00 ` [PATCH v3 01/18] mm: Add folio_nid() Matthew Wilcox (Oracle)
2021-07-01 6:56 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 02/18] mm/memcg: Remove 'page' parameter to mem_cgroup_charge_statistics() Matthew Wilcox (Oracle)
2021-06-30 14:17 ` Johannes Weiner
2021-06-30 4:00 ` [PATCH v3 03/18] mm/memcg: Use the node id in mem_cgroup_update_tree() Matthew Wilcox (Oracle)
2021-06-30 6:55 ` Michal Hocko
2021-06-30 14:18 ` Johannes Weiner
2021-07-01 6:57 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 04/18] mm/memcg: Remove soft_limit_tree_node() Matthew Wilcox (Oracle)
2021-06-30 6:56 ` Michal Hocko
2021-06-30 14:19 ` Johannes Weiner
2021-07-01 7:09 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 05/18] mm/memcg: Convert memcg_check_events to take a node ID Matthew Wilcox (Oracle)
2021-06-30 6:58 ` Michal Hocko
2021-06-30 6:59 ` Michal Hocko
2021-07-01 7:09 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 06/18] mm/memcg: Add folio_memcg() and related functions Matthew Wilcox (Oracle)
2021-06-30 6:53 ` kernel test robot
2021-07-01 7:12 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 07/18] mm/memcg: Convert commit_charge() to take a folio Matthew Wilcox (Oracle)
2021-06-30 4:00 ` [PATCH v3 08/18] mm/memcg: Convert mem_cgroup_charge() " Matthew Wilcox (Oracle)
2021-06-30 7:17 ` kernel test robot
2021-07-01 7:13 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 09/18] mm/memcg: Convert uncharge_page() to uncharge_folio() Matthew Wilcox (Oracle)
2021-07-01 7:15 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 10/18] mm/memcg: Convert mem_cgroup_uncharge() to take a folio Matthew Wilcox (Oracle)
2021-06-30 8:46 ` kernel test robot
2021-07-01 7:17 ` Christoph Hellwig
2021-07-07 12:09 ` Matthew Wilcox
2021-06-30 4:00 ` [PATCH v3 11/18] mm/memcg: Convert mem_cgroup_migrate() to take folios Matthew Wilcox (Oracle)
2021-07-01 7:20 ` Christoph Hellwig
2021-06-30 4:00 ` [PATCH v3 12/18] mm/memcg: Convert mem_cgroup_track_foreign_dirty_slowpath() to folio Matthew Wilcox (Oracle)
2021-06-30 4:00 ` [PATCH v3 13/18] mm/memcg: Add folio_memcg_lock() and folio_memcg_unlock() Matthew Wilcox (Oracle)
2021-06-30 8:32 ` Michal Hocko
2021-07-07 15:10 ` Matthew Wilcox
2021-07-08 7:28 ` Michal Hocko
2021-07-07 17:08 ` Johannes Weiner
2021-07-07 19:28 ` Matthew Wilcox
2021-07-07 20:41 ` Johannes Weiner [this message]
2021-07-09 19:37 ` Matthew Wilcox
2021-06-30 4:00 ` [PATCH v3 14/18] mm/memcg: Convert mem_cgroup_move_account() to use a folio Matthew Wilcox (Oracle)
2021-06-30 8:30 ` Michal Hocko
2021-06-30 11:22 ` Matthew Wilcox
2021-06-30 12:20 ` Michal Hocko
2021-06-30 12:31 ` Matthew Wilcox
2021-06-30 12:45 ` Michal Hocko
2021-07-07 15:25 ` Matthew Wilcox
2021-07-08 7:30 ` Michal Hocko
2021-06-30 4:00 ` [PATCH v3 15/18] mm/memcg: Add mem_cgroup_folio_lruvec() Matthew Wilcox (Oracle)
2021-06-30 8:12 ` kernel test robot
2021-06-30 19:18 ` Matthew Wilcox
2021-06-30 21:21 ` Johannes Weiner
2021-06-30 4:00 ` [PATCH v3 16/18] mm/memcg: Add folio_lruvec_lock() and similar functions Matthew Wilcox (Oracle)
2021-06-30 8:36 ` Michal Hocko
2021-06-30 4:00 ` [PATCH v3 17/18] mm/memcg: Add folio_lruvec_relock_irq() and folio_lruvec_relock_irqsave() Matthew Wilcox (Oracle)
2021-06-30 8:39 ` Michal Hocko
2021-06-30 4:00 ` [PATCH v3 18/18] mm/workingset: Convert workingset_activation to take a folio Matthew Wilcox (Oracle)
2021-06-30 8:44 ` [PATCH v3 00/18] Folio conversion of memcg Michal Hocko
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