From: Waiman Long <llong@redhat.com>
To: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, Shakeel Butt <shakeelb@google.com>,
Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH 2/3] mm, memcg: Remove obsolete memcg_free_kmem()
Date: Fri, 1 Oct 2021 22:03:05 -0400 [thread overview]
Message-ID: <b45fd235-a454-360e-4853-d41db3213e9d@redhat.com> (raw)
In-Reply-To: <YVehP18mCcsXmFy1@carbon.dhcp.thefacebook.com>
On 10/1/21 8:01 PM, Roman Gushchin wrote:
> On Fri, Oct 01, 2021 at 03:09:37PM -0400, Waiman Long wrote:
>> Since commit d648bcc7fe65 ("mm: kmem: make memcg_kmem_enabled()
>> irreversible"), the only thing memcg_free_kmem() does is to call
>> memcg_offline_kmem() when the memcg is still online. However,
>> memcg_offline_kmem() is only called from mem_cgroup_css_free() which
>> cannot be reached if the memcg hasn't been offlined first.
> Hm, is it true? What if online_css() fails?
I just realize that memcg_online_kmem() is called at css_create(). So
yes, if css_online() fails (i.e. ENOMEM), we will need to do
memcg_offline_kmem().
>> As this
>> function now serves no purpose, we should just remove it.
> It looks like we can just use memcg_offline_kmem() instead of
> memcg_free_kmem().
Right, memcg_free_kmem() isn't the right name for that. I agree that we
should just change mem_cgroup_css_free() to call memcg_offline_kmem()
directly. Will update the patch accordingly.
Thanks,
Longman
next prev parent reply other threads:[~2021-10-02 2:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 19:09 [PATCH 0/3] mm, memcg: Miscellaneous cleanups Waiman Long
2021-10-01 19:09 ` [PATCH 1/3] mm, memcg: Don't put offlined memcg into local stock Waiman Long
2021-10-01 21:17 ` kernel test robot
2021-10-01 23:06 ` kernel test robot
2021-10-01 23:51 ` Roman Gushchin
2021-10-02 1:54 ` Waiman Long
2022-01-31 3:55 ` Waiman Long
2022-01-31 17:01 ` Roman Gushchin
2022-01-31 17:09 ` Waiman Long
2022-01-31 17:15 ` Waiman Long
2022-01-31 17:19 ` Roman Gushchin
2022-01-31 17:25 ` Waiman Long
2022-01-31 18:00 ` Shakeel Butt
2022-01-31 17:15 ` Roman Gushchin
2021-10-01 19:09 ` [PATCH 2/3] mm, memcg: Remove obsolete memcg_free_kmem() Waiman Long
2021-10-02 0:01 ` Roman Gushchin
2021-10-02 2:03 ` Waiman Long [this message]
2021-10-01 19:09 ` [PATCH 3/3] mm, memcg: Ensure valid memcg from objcg within a RCU critical section Waiman Long
2021-10-01 20:24 ` Shakeel Butt
2021-10-01 20:34 ` Waiman Long
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