From: Johannes Weiner <hannes@cmpxchg.org>
To: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>,
mhocko@kernel.org, shakeelb@google.com, cgroups@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
duanxiongchun@bytedance.com, longman@redhat.com
Subject: Re: [PATCH v4 01/11] mm: memcontrol: prepare objcg API for non-kmem usage
Date: Wed, 25 May 2022 08:37:58 -0400 [thread overview]
Message-ID: <Yo4jJjBksFVeJHxA@cmpxchg.org> (raw)
In-Reply-To: <Yo3hXe8bF3boWx5C@FVFYT0MHHV2J.usts.net>
On Wed, May 25, 2022 at 03:57:17PM +0800, Muchun Song wrote:
> On Tue, May 24, 2022 at 07:36:24PM -0700, Roman Gushchin wrote:
> > On Tue, May 24, 2022 at 02:05:41PM +0800, Muchun Song wrote:
> > > - memcg_reparent_list_lrus(memcg, parent);
> > > + memcg_reparent_list_lrus(memcg, parent_mem_cgroup(memcg));
> > We effectively dropped this:
> > if (!parent)
> > parent = root_mem_cgroup;
> > Is it safe? (assuming v1 non-hierarchical mode, it's usually when all
> > is getting complicated)
Yes, it's correct. But it's a quiet, incidental cleanup, so I can see
why it's confusing. It might be better to split the dead code removal
into a separate patch - with the following in the changelog ;):
> Since no-hierarchy mode is deprecated after commit bef8620cd8e0
> ("mm: memcg: deprecate the non-hierarchical mode"), so
> parent_mem_cgroup() cannot return a NULL except root memcg,
> however, root memcg will not be offline, so it is safe. Right?
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
To: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>
Cc: Roman Gushchin
<roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>,
mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
duanxiongchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org,
longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org
Subject: Re: [PATCH v4 01/11] mm: memcontrol: prepare objcg API for non-kmem usage
Date: Wed, 25 May 2022 08:37:58 -0400 [thread overview]
Message-ID: <Yo4jJjBksFVeJHxA@cmpxchg.org> (raw)
In-Reply-To: <Yo3hXe8bF3boWx5C-t1y1lxtqHnnw2QbUemf3bixXY32XiHfO@public.gmane.org>
On Wed, May 25, 2022 at 03:57:17PM +0800, Muchun Song wrote:
> On Tue, May 24, 2022 at 07:36:24PM -0700, Roman Gushchin wrote:
> > On Tue, May 24, 2022 at 02:05:41PM +0800, Muchun Song wrote:
> > > - memcg_reparent_list_lrus(memcg, parent);
> > > + memcg_reparent_list_lrus(memcg, parent_mem_cgroup(memcg));
> > We effectively dropped this:
> > if (!parent)
> > parent = root_mem_cgroup;
> > Is it safe? (assuming v1 non-hierarchical mode, it's usually when all
> > is getting complicated)
Yes, it's correct. But it's a quiet, incidental cleanup, so I can see
why it's confusing. It might be better to split the dead code removal
into a separate patch - with the following in the changelog ;):
> Since no-hierarchy mode is deprecated after commit bef8620cd8e0
> ("mm: memcg: deprecate the non-hierarchical mode"), so
> parent_mem_cgroup() cannot return a NULL except root memcg,
> however, root memcg will not be offline, so it is safe. Right?
next prev parent reply other threads:[~2022-05-25 12:38 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-24 6:05 [PATCH v4 00/11] Use obj_cgroup APIs to charge the LRU pages Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 01/11] mm: memcontrol: prepare objcg API for non-kmem usage Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 19:01 ` Johannes Weiner
2022-05-24 19:01 ` Johannes Weiner
2022-05-25 8:46 ` Muchun Song
2022-05-25 8:46 ` Muchun Song
2022-05-25 2:36 ` Roman Gushchin
2022-05-25 2:36 ` Roman Gushchin
2022-05-25 7:57 ` Muchun Song
2022-05-25 7:57 ` Muchun Song
2022-05-25 12:37 ` Johannes Weiner [this message]
2022-05-25 12:37 ` Johannes Weiner
2022-05-25 13:08 ` Muchun Song
2022-05-25 13:08 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 02/11] mm: memcontrol: introduce compact_folio_lruvec_lock_irqsave Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 19:22 ` Johannes Weiner
2022-05-24 19:22 ` Johannes Weiner
2022-05-25 9:38 ` Muchun Song
2022-05-25 9:38 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 03/11] mm: memcontrol: make lruvec lock safe when LRU pages are reparented Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 19:23 ` Waiman Long
2022-05-25 10:20 ` Muchun Song
2022-05-25 10:20 ` Muchun Song
2022-05-25 14:59 ` Waiman Long
2022-05-25 14:59 ` Waiman Long
2022-05-24 19:27 ` Johannes Weiner
2022-05-24 19:27 ` Johannes Weiner
2022-05-25 9:53 ` Muchun Song
2022-05-25 9:53 ` Muchun Song
2022-05-25 12:30 ` Johannes Weiner
2022-05-25 12:30 ` Johannes Weiner
2022-05-25 13:03 ` Muchun Song
2022-05-25 13:03 ` Muchun Song
2022-05-25 14:48 ` Johannes Weiner
2022-05-25 14:48 ` Johannes Weiner
2022-05-25 15:38 ` Muchun Song
2022-05-25 15:38 ` Muchun Song
2022-05-26 20:17 ` Waiman Long
2022-05-26 20:17 ` Waiman Long
2022-05-27 2:55 ` Muchun Song
2022-05-27 2:55 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 04/11] mm: vmscan: rework move_pages_to_lru() Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 19:38 ` Johannes Weiner
2022-05-24 19:38 ` Johannes Weiner
2022-05-25 11:38 ` Muchun Song
2022-05-25 11:38 ` Muchun Song
2022-05-24 19:52 ` Waiman Long
2022-05-24 19:52 ` Waiman Long
2022-05-25 11:43 ` Muchun Song
2022-05-25 11:43 ` Muchun Song
2022-05-25 2:43 ` Roman Gushchin
2022-05-25 2:43 ` Roman Gushchin
2022-05-25 11:41 ` Muchun Song
2022-05-25 11:41 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 05/11] mm: thp: introduce folio_split_queue_lock{_irqsave}() Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 06/11] mm: thp: make split queue lock safe when LRU pages are reparented Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-25 2:54 ` Roman Gushchin
2022-05-25 2:54 ` Roman Gushchin
2022-05-25 11:44 ` Muchun Song
2022-05-25 11:44 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 07/11] mm: memcontrol: make all the callers of {folio,page}_memcg() safe Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-25 3:03 ` Roman Gushchin
2022-05-25 3:03 ` Roman Gushchin
2022-05-25 11:51 ` Muchun Song
2022-05-25 11:51 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 08/11] mm: memcontrol: introduce memcg_reparent_ops Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 09/11] mm: memcontrol: use obj_cgroup APIs to charge the LRU pages Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 12:29 ` kernel test robot
2022-05-24 18:16 ` kernel test robot
2022-05-24 18:16 ` kernel test robot
2022-05-25 7:14 ` [mm] bec0ae1210: WARNING:possible_recursive_locking_detected kernel test robot
2022-05-25 7:14 ` kernel test robot
2022-05-24 6:05 ` [PATCH v4 10/11] mm: lru: add VM_BUG_ON_FOLIO to lru maintenance function Muchun Song
2022-05-24 6:05 ` Muchun Song
2022-05-24 19:44 ` Johannes Weiner
2022-05-24 19:44 ` Johannes Weiner
2022-05-25 11:59 ` Muchun Song
2022-05-25 11:59 ` Muchun Song
2022-05-25 2:40 ` Roman Gushchin
2022-05-25 2:40 ` Roman Gushchin
2022-05-25 11:58 ` Muchun Song
2022-05-24 6:05 ` [PATCH v4 11/11] mm: lru: use lruvec lock to serialize memcg changes Muchun Song
2022-05-24 6:05 ` Muchun Song
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