From: Roman Gushchin <roman.gushchin@linux.dev>
To: Vasily Averin <vvs@openvz.org>
Cc: "Shakeel Butt" <shakeelb@google.com>,
"Michal Koutný" <mkoutny@suse.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
kernel@openvz.org, "Florian Westphal" <fw@strlen.de>,
LKML <linux-kernel@vger.kernel.org>,
"Michal Hocko" <mhocko@suse.com>,
Cgroups <cgroups@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>
Subject: Re: [PATCH memcg v4] net: set proper memcg for net_init hooks allocations
Date: Wed, 27 Apr 2022 15:36:03 -0700 [thread overview]
Message-ID: <YmnFUwhmqJwYGQ5j@carbon> (raw)
In-Reply-To: <6b18f82d-1950-b38e-f3f5-94f6c23f0edb@openvz.org>
On Thu, Apr 28, 2022 at 01:16:53AM +0300, Vasily Averin wrote:
> On 4/27/22 18:06, Shakeel Butt wrote:
> > On Wed, Apr 27, 2022 at 5:22 AM Michal Koutný <mkoutny@suse.com> wrote:
> >>
> >> On Tue, Apr 26, 2022 at 10:23:32PM -0700, Shakeel Butt <shakeelb@google.com> wrote:
> >>> [...]
> >>>>
> >>>> +static inline struct mem_cgroup *get_mem_cgroup_from_obj(void *p)
> >>>> +{
> >>>> + struct mem_cgroup *memcg;
> >>>> +
> >>>
> >>> Do we need memcg_kmem_enabled() check here or maybe
> >>> mem_cgroup_from_obj() should be doing memcg_kmem_enabled() instead of
> >>> mem_cgroup_disabled() as we can have "cgroup.memory=nokmem" boot
> >>> param.
>
> Shakeel, unfortunately I'm not ready to answer this question right now.
> I even did not noticed that memcg_kmem_enabled() and mem_cgroup_disabled()
> have a different nature.
> If you have no objections I'm going to keep this place as is and investigate
> this question later.
>
> >> I reckon such a guard is on the charge side and readers should treat
> >> NULL and root_mem_group equally. Or is there a case when these two are
> >> different?
> >>
> >> (I can see it's different semantics when stored in current->active_memcg
> >> (and active_memcg() getter) but for such "outer" callers like here it
> >> seems equal.)
>
> Dear Michal,
> I may have misunderstood your point of view, so let me explain my vision
> in more detail.
> I do not think that NULL and root_mem_cgroup are equal here:
> - we have enabled cgroups and well-defined root_mem_cgroup,
> - this function is called from inside memcg-limited container,
> - we tried to get memcg from net, but without success,
> and as result got NULL from mem_cgroup_from_obj()
> (frankly speaking I do not think this situation is really possible)
> If we keep memcg = NULL, then current's memcg will not be masked and
> net_init's allocations will be accounted to current's memcg.
> So we need to set active_memcg to root_mem_cgroup, it helps to avoid
> incorrect accounting.
It's way out of scope of this patch, but I think we need to stop
using NULL as root_mem_cgroup/system scope indicator. Remaining use cases
will be like end of cgroup iteration, active memcg not set, parent of the
root memcg, etc.
We can point root_mem_cgroup at a statically allocated structure
on both CONFIG_MEMCG and !CONFIG_MEMCG.
Does it sound reasonable or I'm missing some important points?
Thanks!
next prev parent reply other threads:[~2022-04-27 22:36 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-28 7:17 [PATCH RFC] net: memcg accounting for veth devices Vasily Averin
2022-02-28 14:36 ` Luis Chamberlain
2022-03-01 18:09 ` Shakeel Butt
2022-03-01 18:28 ` Luis Chamberlain
2022-03-01 20:50 ` Eric W. Biederman
2022-03-01 21:25 ` Luis Chamberlain
2022-03-01 21:31 ` Luis Chamberlain
2022-03-02 14:43 ` Eric W. Biederman
2022-03-02 21:52 ` Luis Chamberlain
2022-03-02 13:30 ` King, Colin
2022-04-11 9:40 ` problem with accounting of allocations called from __net_init hooks Vasily Averin
2022-04-17 6:39 ` [PATCH memcg RFC] net: set proper memcg for net_init hooks allocations Vasily Averin
2022-04-21 15:56 ` Shakeel Butt
2022-04-22 20:01 ` Vasily Averin
2022-04-22 20:09 ` Vasily Averin
2022-04-22 20:22 ` Shakeel Butt
2022-04-23 7:56 ` [PATCH] " Vasily Averin
2022-04-23 9:39 ` kernel test robot
2022-04-23 9:39 ` kernel test robot
2022-04-23 10:31 ` kernel test robot
2022-04-23 15:38 ` [PATCH memcg v2] " Vasily Averin
2022-04-24 14:46 ` [net] 3b379e5391: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2022-04-25 10:56 ` [PATCH memcg v3] net: set proper memcg for net_init hooks allocations Vasily Averin
2022-04-26 2:50 ` Roman Gushchin
2022-04-26 5:58 ` Vasily Averin
2022-04-26 6:43 ` [PATCH memcg v4] " Vasily Averin
2022-04-26 22:13 ` Roman Gushchin
2022-04-27 5:23 ` Shakeel Butt
2022-04-27 12:22 ` Michal Koutný
2022-04-27 15:06 ` Shakeel Butt
2022-04-27 22:16 ` Vasily Averin
2022-04-27 22:36 ` Roman Gushchin [this message]
2022-04-28 4:37 ` Vasily Averin
2022-04-27 22:47 ` Shakeel Butt
2022-05-01 13:44 ` Vasily Averin
2022-05-01 21:09 ` Roman Gushchin
2022-05-02 0:10 ` [PATCH memcg v5] " Vasily Averin
2022-05-30 8:57 ` Vasily Averin
2022-06-03 4:19 ` [PATCH memcg v6] " Vasily Averin
2022-06-06 13:49 ` Qian Cai
2022-06-06 17:37 ` Vasily Averin
2022-06-06 18:43 ` Qian Cai
2022-06-06 18:45 ` Vasily Averin
2022-06-07 5:58 ` Shakeel Butt
2022-06-07 12:37 ` Vasily Averin
2022-06-07 14:10 ` Shakeel Butt
2022-09-18 9:28 ` [sparc64] fails to boot, (was: Re: [PATCH memcg v6] net: set proper memcg for net_init hooks allocations) Anatoly Pugachev
2022-09-21 14:44 ` Anatoly Pugachev
2022-09-21 17:02 ` Michal Koutný
2022-09-26 13:06 ` Anatoly Pugachev
2022-09-26 17:28 ` Jakub Kicinski
2022-09-26 17:32 ` Shakeel Butt
2022-09-26 17:36 ` Andrew Morton
2022-09-26 19:00 ` Shakeel Butt
2022-09-27 9:54 ` Vlastimil Babka
2022-09-28 7:54 ` Thorsten Leemhuis
2022-09-28 7:21 ` [sparc64] fails to boot, (was: Re: [PATCH memcg v6] net: set proper memcg for net_init hooks allocations) #forregzbot Thorsten Leemhuis
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