From: Roman Gushchin <guro@fb.com>
To: Waiman Long <longman@redhat.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 1/3] mm, memcg: Don't put offlined memcg into local stock
Date: Mon, 31 Jan 2022 09:19:29 -0800 [thread overview]
Message-ID: <YfgaIcSJhqEOnh65@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <c950a93d-bb70-9a97-dabe-a1d58d755dad@redhat.com>
On Mon, Jan 31, 2022 at 12:15:19PM -0500, Waiman Long wrote:
> On 1/31/22 12:09, Waiman Long wrote:
> > On 1/31/22 12:01, Roman Gushchin wrote:
> > > On Sun, Jan 30, 2022 at 10:55:56PM -0500, Waiman Long wrote:
> > > > On 10/1/21 19:51, Roman Gushchin wrote:
> > > > > On Fri, Oct 01, 2021 at 03:09:36PM -0400, Waiman Long wrote:
> > > > > > When freeing a page associated with an offlined memcg, refill_stock()
> > > > > > will put it into local stock delaying its demise until another memcg
> > > > > > comes in to take its place in the stock. To avoid that, we now check
> > > > > > for offlined memcg and go directly in this case to the slowpath for
> > > > > > the uncharge via the repurposed cancel_charge() function.
> > > > > Hi Waiman!
> > > > >
> > > > > I'm afraid it can make a cleanup of a dying cgroup slower: for every
> > > > > released page we'll potentially traverse the whole cgroup tree and
> > > > > decrease atomic page counters.
> > > > >
> > > > > I'm not sure I understand the benefits we get from this change which
> > > > > do justify the slowdown on the cleanup path.
> > > > >
> > > > > Thanks!
> > > > I was notified of a lockdep splat that this patch may help to prevent.
> > > Would you mind to test this patch:
> > > https://www.spinics.net/lists/cgroups/msg31244.html ?
> > >
> > > It should address this dependency.
> >
> > Thanks for the pointer. I believe that your patch should be able to
> > address this circular locking dependency.
> >
> > Feel free to add my
> >
> > Reviewed-by: Waiman Long <longman@redhat.com>
>
> BTW, have you posted it to lkml? If not, would you mind doing so?
Not yet.
I was waiting for Alexander to confirm that it resolves the originally reported
issue. I just pinged him, will wait for tomorrow and post the patch in any case.
Thanks!
WARNING: multiple messages have this Message-ID (diff)
From: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>
To: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Vladimir Davydov
<vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>
Subject: Re: [PATCH 1/3] mm, memcg: Don't put offlined memcg into local stock
Date: Mon, 31 Jan 2022 09:19:29 -0800 [thread overview]
Message-ID: <YfgaIcSJhqEOnh65@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <c950a93d-bb70-9a97-dabe-a1d58d755dad-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
On Mon, Jan 31, 2022 at 12:15:19PM -0500, Waiman Long wrote:
> On 1/31/22 12:09, Waiman Long wrote:
> > On 1/31/22 12:01, Roman Gushchin wrote:
> > > On Sun, Jan 30, 2022 at 10:55:56PM -0500, Waiman Long wrote:
> > > > On 10/1/21 19:51, Roman Gushchin wrote:
> > > > > On Fri, Oct 01, 2021 at 03:09:36PM -0400, Waiman Long wrote:
> > > > > > When freeing a page associated with an offlined memcg, refill_stock()
> > > > > > will put it into local stock delaying its demise until another memcg
> > > > > > comes in to take its place in the stock. To avoid that, we now check
> > > > > > for offlined memcg and go directly in this case to the slowpath for
> > > > > > the uncharge via the repurposed cancel_charge() function.
> > > > > Hi Waiman!
> > > > >
> > > > > I'm afraid it can make a cleanup of a dying cgroup slower: for every
> > > > > released page we'll potentially traverse the whole cgroup tree and
> > > > > decrease atomic page counters.
> > > > >
> > > > > I'm not sure I understand the benefits we get from this change which
> > > > > do justify the slowdown on the cleanup path.
> > > > >
> > > > > Thanks!
> > > > I was notified of a lockdep splat that this patch may help to prevent.
> > > Would you mind to test this patch:
> > > https://www.spinics.net/lists/cgroups/msg31244.html ?
> > >
> > > It should address this dependency.
> >
> > Thanks for the pointer. I believe that your patch should be able to
> > address this circular locking dependency.
> >
> > Feel free to add my
> >
> > Reviewed-by: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>
> BTW, have you posted it to lkml? If not, would you mind doing so?
Not yet.
I was waiting for Alexander to confirm that it resolves the originally reported
issue. I just pinged him, will wait for tomorrow and post the patch in any case.
Thanks!
next prev parent reply other threads:[~2022-01-31 17:20 UTC|newest]
Thread overview: 39+ 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 ` 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 19:09 ` Waiman Long
2021-10-01 21:17 ` kernel test robot
2021-10-01 21:17 ` kernel test robot
2021-10-01 21:17 ` kernel test robot
2021-10-01 23:06 ` kernel test robot
2021-10-01 23:06 ` kernel test robot
2021-10-01 23:06 ` kernel test robot
2021-10-01 23:51 ` Roman Gushchin
2021-10-01 23:51 ` Roman Gushchin
2021-10-02 1:54 ` Waiman Long
2021-10-02 1:54 ` Waiman Long
2022-01-31 3:55 ` Waiman Long
2022-01-31 3:55 ` Waiman Long
2022-01-31 17:01 ` Roman Gushchin
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 [this message]
2022-01-31 17:19 ` Roman Gushchin
2022-01-31 17:25 ` Waiman Long
2022-01-31 17:25 ` Waiman Long
2022-01-31 18:00 ` Shakeel Butt
2022-01-31 18:00 ` Shakeel Butt
2022-01-31 17:15 ` Roman Gushchin
2022-01-31 17:15 ` Roman Gushchin
2021-10-01 19:09 ` [PATCH 2/3] mm, memcg: Remove obsolete memcg_free_kmem() Waiman Long
2021-10-01 19:09 ` Waiman Long
2021-10-02 0:01 ` Roman Gushchin
2021-10-02 0:01 ` Roman Gushchin
2021-10-02 2:03 ` Waiman Long
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 19:09 ` Waiman Long
2021-10-01 20:24 ` Shakeel Butt
2021-10-01 20:24 ` Shakeel Butt
2021-10-01 20:24 ` Shakeel Butt
2021-10-01 20:34 ` Waiman Long
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