From: Tejun Heo <tj@kernel.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>,
Yosry Ahmed <yosryahmed@google.com>,
Alistair Popple <apopple@nvidia.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, jhubbard@nvidia.com,
tjmercier@google.com, hannes@cmpxchg.org, surenb@google.com,
mkoutny@suse.com, daniel@ffwll.ch,
"Daniel P . Berrange" <berrange@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>,
Zefan Li <lizefan.x@bytedance.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 14/19] mm: Introduce a cgroup for pinned memory
Date: Tue, 21 Feb 2023 09:49:12 -1000 [thread overview]
Message-ID: <Y/UgOEv2/KzapGPN@slm.duckdns.org> (raw)
In-Reply-To: <Y/UfS8TDIXhUlJ/I@slm.duckdns.org>
On Tue, Feb 21, 2023 at 09:45:15AM -1000, Tejun Heo wrote:
> > Multiple cgroup can pin the same page, so it is not as simple as just
> > transfering ownership, we need multi-ownership and to really fix the
> > memcg limitations with MAP_SHARED without an API impact.
> >
> > You are right that pinning is really just a special case of
> > allocation, but there is a reason the memcg was left with weak support
> > for MAP_SHARED and changing that may be more than just hard but an
> > infeasible trade off..
> >
> > At least I don't have a good idea how to even approach building a
> > reasonable datstructure that can track the number of
> > charges per-cgroup per page. :\
>
> As I wrote above, I don't think the problem here is the case of pages being
> shared by multiple cgroups concurrently. We can leave that problem for
> another thread. However, if we want to support accounting and control of
> pinned memory, we really shouldn't introduce a fundmental discrepancy like
> the owner and pinner disagreeing with each other. At least conceptually, the
> solution is rather straight-forward - whoever pins a page should also claim
> the ownership of it.
Ah, sorry, I missed the part about multiple cgroups pinning the same page.
Yeah, I can't think of a good answer for that.
Thanks.
--
tejun
next prev parent reply other threads:[~2023-02-21 19:49 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-06 7:47 [PATCH 00/19] mm: Introduce a cgroup to limit the amount of locked and " Alistair Popple
2023-02-06 7:47 ` [PATCH 01/19] mm: Introduce vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 02/19] drivers/vhost: Convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 03/19] drivers/vdpa: Convert vdpa to use the new vm_structure Alistair Popple
2023-02-06 7:47 ` [PATCH 04/19] infiniband/umem: Convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 05/19] RMDA/siw: " Alistair Popple
2023-02-12 17:32 ` Bernard Metzler
2023-02-06 7:47 ` [PATCH 06/19] RDMA/usnic: convert " Alistair Popple
2023-02-06 7:47 ` [PATCH 07/19] vfio/type1: Charge pinned pages to pinned_vm instead of locked_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 08/19] vfio/spapr_tce: Convert accounting to pinned_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 09/19] io_uring: convert to use vm_account Alistair Popple
2023-02-06 15:29 ` Jens Axboe
2023-02-07 1:03 ` Alistair Popple
2023-02-07 14:28 ` Jens Axboe
2023-02-07 14:55 ` Jason Gunthorpe
2023-02-07 17:05 ` Jens Axboe
2023-02-13 11:30 ` Alistair Popple
2023-02-06 7:47 ` [PATCH 10/19] net: skb: Switch to using vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 11/19] xdp: convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 12/19] kvm/book3s_64_vio: Convert account_locked_vm() to vm_account_pinned() Alistair Popple
2023-02-06 7:47 ` [PATCH 13/19] fpga: dfl: afu: convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 14/19] mm: Introduce a cgroup for pinned memory Alistair Popple
2023-02-06 21:01 ` Yosry Ahmed
2023-02-06 21:14 ` Tejun Heo
2023-02-06 22:32 ` Yosry Ahmed
2023-02-06 22:36 ` Tejun Heo
2023-02-06 22:39 ` Yosry Ahmed
2023-02-06 23:25 ` Tejun Heo
2023-02-06 23:34 ` Yosry Ahmed
2023-02-06 23:40 ` Jason Gunthorpe
2023-02-07 0:32 ` Tejun Heo
2023-02-07 12:19 ` Jason Gunthorpe
2023-02-15 19:00 ` Michal Hocko
2023-02-15 19:07 ` Jason Gunthorpe
2023-02-16 8:04 ` Michal Hocko
2023-02-16 12:45 ` Jason Gunthorpe
2023-02-21 16:51 ` Tejun Heo
2023-02-21 17:25 ` Jason Gunthorpe
2023-02-21 17:29 ` Tejun Heo
2023-02-21 17:51 ` Jason Gunthorpe
2023-02-21 18:07 ` Tejun Heo
2023-02-21 19:26 ` Jason Gunthorpe
2023-02-21 19:45 ` Tejun Heo
2023-02-21 19:49 ` Tejun Heo [this message]
2023-02-21 19:57 ` Jason Gunthorpe
2023-02-22 11:38 ` Alistair Popple
2023-02-22 12:57 ` Jason Gunthorpe
2023-02-22 22:59 ` Alistair Popple
2023-02-23 0:05 ` Christoph Hellwig
2023-02-23 0:35 ` Alistair Popple
2023-02-23 1:53 ` Jason Gunthorpe
2023-02-23 9:12 ` Daniel P. Berrangé
2023-02-23 17:31 ` Jason Gunthorpe
2023-02-23 17:18 ` T.J. Mercier
2023-02-23 17:28 ` Jason Gunthorpe
2023-02-23 18:03 ` Yosry Ahmed
2023-02-23 18:10 ` Jason Gunthorpe
2023-02-23 18:14 ` Yosry Ahmed
2023-02-23 18:15 ` Tejun Heo
2023-02-23 18:17 ` Jason Gunthorpe
2023-02-23 18:22 ` Tejun Heo
2023-02-07 1:00 ` Waiman Long
2023-02-07 1:03 ` Tejun Heo
2023-02-07 1:50 ` Alistair Popple
2023-02-06 7:47 ` [PATCH 15/19] mm/util: Extend vm_account to charge pages against the pin cgroup Alistair Popple
2023-02-06 7:47 ` [PATCH 16/19] mm/util: Refactor account_locked_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 17/19] mm: Convert mmap and mlock to use account_locked_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 18/19] mm/mmap: Charge locked memory to pins cgroup Alistair Popple
2023-02-06 21:12 ` Yosry Ahmed
2023-02-06 7:47 ` [PATCH 19/19] selftests/vm: Add pins-cgroup selftest for mlock/mmap Alistair Popple
2023-02-16 11:01 ` [PATCH 00/19] mm: Introduce a cgroup to limit the amount of locked and pinned memory David Hildenbrand
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