Messages in this thread | | | Date | Mon, 11 Apr 2022 12:40:29 +0300 | From | Vasily Averin <> | Subject | problem with accounting of allocations called from __net_init hooks |
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On 3/1/22 21:09, Shakeel Butt wrote: > On Mon, Feb 28, 2022 at 06:36:58AM -0800, Luis Chamberlain wrote: >> On Mon, Feb 28, 2022 at 10:17:16AM +0300, Vasily Averin wrote: >> > Following one-liner running inside memcg-limited container consumes >> > huge number of host memory and can trigger global OOM. >> > >> > for i in `seq 1 xxx` ; do ip l a v$i type veth peer name vp$i ; done >> > >> > Patch accounts most part of these allocations and can protect host. >> > ---[cut]--- >> > It is not polished, and perhaps should be splitted. >> > obviously it affects other kind of netdevices too. >> > Unfortunately I'm not sure that I will have enough time to handle it properly >> > and decided to publish current patch version as is. >> > OpenVz workaround it by using per-container limit for number of >> > available netdevices, but upstream does not have any kind of >> > per-container configuration. >> > ------
I've noticed that __register_pernet_operations() executes init hook of registered pernet_operation structure in all found net namespaces.
Usually these hooks are called by process related to specified net namespace, and all marked allocation are accounted to related container: i.e. objects related to netns in container A are accounted to memcg of container A, objects allocated inside container B are accounted to corresponding memcg B, and so on.
However __register_pernet_operations() calls the same hooks in one context, and as result all marked allocations are accounted to one memcg. It is quite rare scenario, however current processing looks incorrect for me.
I expect we can take memcg from 'struct net', because of this structure is accounted per se. then we can use set_active_memcg() before init hook execution. However I'm not sure it is fully correct.
Could you please advise some better solution?
Thank you, Vasily Averin
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