From: Richard Palethorpe <rpalethorpe@suse.de>
To: Roman Gushchin <guro@fb.com>
Cc: ltp@lists.linux.it, Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
Shakeel Butt <shakeelb@google.com>,
"Christoph Lameter" <cl@linux.com>,
Michal Hocko <mhocko@kernel.org>, Tejun Heo <tj@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] mm: memcg/slab: Stop reparented obj_cgroups from charging root
Date: Fri, 16 Oct 2020 06:40:57 +0100 [thread overview]
Message-ID: <87v9fasp7a.fsf@suse.de> (raw)
In-Reply-To: <20201014200833.GA19363@carbon.lan>
Hello Roman,
Roman Gushchin <guro@fb.com> writes:
> Hi Richard!
>
>> SLAB objects which outlive their memcg are moved to their parent
>> memcg where they may be uncharged. However if they are moved to the
>> root memcg, uncharging will result in negative page counter values as
>> root has no page counters.
>>
>> To prevent this, we check whether we are about to uncharge the root
>> memcg and skip it if we are. Possibly instead; the obj_cgroups should
>> be removed from their slabs and any per cpu stocks instead of
>> reparenting them to root?
>
> It would be really complex. I think your fix is totally fine.
> We have similar checks in cancel_charge(), uncharge_batch(),
> mem_cgroup_swapout(), mem_cgroup_uncharge_swap() etc.
>
>
> Acked-by: Roman Gushchin <guro@fb.com>
>
> Thanks!
Great I will respin.
--
Thank you,
Richard.
WARNING: multiple messages have this Message-ID (diff)
From: Richard Palethorpe <rpalethorpe@suse.de>
To: ltp@lists.linux.it
Subject: [LTP] [RFC PATCH] mm: memcg/slab: Stop reparented obj_cgroups from charging root
Date: Fri, 16 Oct 2020 06:40:57 +0100 [thread overview]
Message-ID: <87v9fasp7a.fsf@suse.de> (raw)
In-Reply-To: <20201014200833.GA19363@carbon.lan>
Hello Roman,
Roman Gushchin <guro@fb.com> writes:
> Hi Richard!
>
>> SLAB objects which outlive their memcg are moved to their parent
>> memcg where they may be uncharged. However if they are moved to the
>> root memcg, uncharging will result in negative page counter values as
>> root has no page counters.
>>
>> To prevent this, we check whether we are about to uncharge the root
>> memcg and skip it if we are. Possibly instead; the obj_cgroups should
>> be removed from their slabs and any per cpu stocks instead of
>> reparenting them to root?
>
> It would be really complex. I think your fix is totally fine.
> We have similar checks in cancel_charge(), uncharge_batch(),
> mem_cgroup_swapout(), mem_cgroup_uncharge_swap() etc.
>
>
> Acked-by: Roman Gushchin <guro@fb.com>
>
> Thanks!
Great I will respin.
--
Thank you,
Richard.
next prev parent reply other threads:[~2020-10-16 5:41 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 19:07 [RFC PATCH] mm: memcg/slab: Stop reparented obj_cgroups from charging root Richard Palethorpe
2020-10-14 19:07 ` [LTP] " Richard Palethorpe
2020-10-14 20:08 ` Roman Gushchin
2020-10-14 20:08 ` [LTP] " Roman Gushchin
2020-10-16 5:40 ` Richard Palethorpe [this message]
2020-10-16 5:40 ` Richard Palethorpe
2020-10-16 6:32 ` [LTP] [PATCH v2] " Richard Palethorpe
2020-10-16 9:47 ` [RFC PATCH] " Michal Koutný
2020-10-16 9:47 ` [LTP] " Michal =?unknown-8bit?q?Koutn=C3=BD?=
2020-10-16 10:41 ` Richard Palethorpe
2020-10-16 10:41 ` [LTP] " Richard Palethorpe
2020-10-16 15:05 ` Richard Palethorpe
2020-10-16 15:05 ` [LTP] " Richard Palethorpe
2020-10-16 17:26 ` Michal Koutný
2020-10-16 17:26 ` [LTP] " Michal =?unknown-8bit?q?Koutn=C3=BD?=
2020-10-16 14:53 ` Johannes Weiner
2020-10-16 14:53 ` [LTP] " Johannes Weiner
2020-10-16 17:02 ` Roman Gushchin
2020-10-16 17:02 ` [LTP] " Roman Gushchin
2020-10-16 17:15 ` Michal Koutný
2020-10-16 17:15 ` [LTP] " Michal =?unknown-8bit?q?Koutn=C3=BD?=
2020-10-19 8:45 ` Richard Palethorpe
2020-10-19 8:45 ` [LTP] " Richard Palethorpe
2020-10-19 9:58 ` [PATCH v3] " Richard Palethorpe
2020-10-19 9:58 ` [LTP] " Richard Palethorpe
2020-10-19 16:58 ` Shakeel Butt
2020-10-19 16:58 ` [LTP] " Shakeel Butt
2020-10-19 16:58 ` Shakeel Butt
2020-10-20 5:52 ` Richard Palethorpe
2020-10-20 5:52 ` [LTP] " Richard Palethorpe
2020-10-20 13:49 ` Richard Palethorpe
2020-10-20 13:49 ` [LTP] " Richard Palethorpe
2020-10-20 16:56 ` Shakeel Butt
2020-10-20 16:56 ` [LTP] " Shakeel Butt
2020-10-20 16:56 ` Shakeel Butt
2020-10-21 20:32 ` Roman Gushchin
2020-10-21 20:32 ` [LTP] " Roman Gushchin
2020-10-20 17:24 ` Michal Koutný
2020-10-20 17:24 ` [LTP] " Michal =?unknown-8bit?q?Koutn=C3=BD?=
2020-10-22 7:04 ` Richard Palethorpe
2020-10-22 7:04 ` [LTP] " Richard Palethorpe
2020-10-22 12:28 ` [PATCH v4] " Richard Palethorpe
2020-10-22 12:28 ` [LTP] " Richard Palethorpe
2020-10-22 16:37 ` Shakeel Butt
2020-10-22 16:37 ` [LTP] " Shakeel Butt
2020-10-22 16:37 ` Shakeel Butt
2020-10-22 17:25 ` Roman Gushchin
2020-10-22 17:25 ` [LTP] " Roman Gushchin
2020-10-22 23:59 ` Shakeel Butt
2020-10-22 23:59 ` [LTP] " Shakeel Butt
2020-10-22 23:59 ` Shakeel Butt
2020-10-23 0:40 ` Roman Gushchin
2020-10-23 0:40 ` [LTP] " Roman Gushchin
2020-10-23 15:44 ` Johannes Weiner
2020-10-23 15:44 ` [LTP] " Johannes Weiner
2020-10-23 16:41 ` Shakeel Butt
2020-10-23 16:41 ` [LTP] " Shakeel Butt
2020-10-23 16:41 ` Shakeel Butt
2020-10-26 7:32 ` Richard Palethorpe
2020-10-26 7:32 ` [LTP] " Richard Palethorpe
2020-10-26 23:14 ` Roman Gushchin
2020-10-26 23:14 ` [LTP] " Roman Gushchin
2020-10-19 22:28 ` [RFC PATCH] " Roman Gushchin
2020-10-19 22:28 ` [LTP] " Roman Gushchin
2020-10-20 6:04 ` Richard Palethorpe
2020-10-20 6:04 ` [LTP] " Richard Palethorpe
2020-10-20 12:02 ` Richard Palethorpe
2020-10-20 12:02 ` [LTP] " Richard Palethorpe
2020-10-20 14:48 ` Richard Palethorpe
2020-10-20 14:48 ` [LTP] " Richard Palethorpe
2020-10-20 16:27 ` Michal Koutný
2020-10-20 16:27 ` [LTP] " Michal =?unknown-8bit?q?Koutn=C3=BD?=
2020-10-20 17:07 ` Roman Gushchin
2020-10-20 17:07 ` [LTP] " Roman Gushchin
2020-10-20 18:18 ` Johannes Weiner
2020-10-20 18:18 ` [LTP] " Johannes Weiner
2020-10-21 19:33 ` Roman Gushchin
2020-10-21 19:33 ` [LTP] " Roman Gushchin
2020-10-23 16:30 ` Johannes Weiner
2020-10-23 16:30 ` [LTP] " Johannes Weiner
2020-11-10 1:27 ` Roman Gushchin
2020-11-10 1:27 ` [LTP] " Roman Gushchin
2020-11-10 15:11 ` Shakeel Butt
2020-11-10 15:11 ` [LTP] " Shakeel Butt
2020-11-10 19:13 ` Roman Gushchin
2020-11-10 19:13 ` [LTP] " Roman Gushchin
2020-11-20 17:46 ` Michal Koutný
2020-11-20 17:46 ` [LTP] " Michal =?unknown-8bit?q?Koutn=C3=BD?=
2020-11-03 13:22 ` Michal Hocko
2020-11-03 13:22 ` [LTP] " Michal Hocko
2020-11-03 21:30 ` Roman Gushchin
2020-11-03 21:30 ` [LTP] " Roman Gushchin
2020-10-20 16:55 ` Shakeel Butt
2020-10-20 16:55 ` [LTP] " Shakeel Butt
2020-10-20 17:17 ` Roman Gushchin
2020-10-20 17:17 ` [LTP] " Roman Gushchin
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