Messages in this thread | | | Subject | Re: [PATCH v2] fs: fsnotify: account fsnotify metadata to kmemcg | From | "Yang Shi" <> | Date | Wed, 15 Nov 2017 01:32:16 +0800 |
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On 11/14/17 1:39 AM, Michal Hocko wrote: > On Tue 14-11-17 03:10:22, Yang Shi wrote: >> >> >> On 11/9/17 5:54 AM, Michal Hocko wrote: >>> [Sorry for the late reply] >>> >>> On Tue 31-10-17 11:12:38, Jan Kara wrote: >>>> On Tue 31-10-17 00:39:58, Yang Shi wrote: >>> [...] >>>>> I do agree it is not fair and not neat to account to producer rather than >>>>> misbehaving consumer, but current memcg design looks not support such use >>>>> case. And, the other question is do we know who is the listener if it >>>>> doesn't read the events? >>>> >>>> So you never know who will read from the notification file descriptor but >>>> you can simply account that to the process that created the notification >>>> group and that is IMO the right process to account to. >>> >>> Yes, if the creator is de-facto owner which defines the lifetime of >>> those objects then this should be a target of the charge. >>> >>>> I agree that current SLAB memcg accounting does not allow to account to a >>>> different memcg than the one of the running process. However I *think* it >>>> should be possible to add such interface. Michal? >>> >>> We do have memcg_kmem_charge_memcg but that would require some plumbing >>> to hook it into the specific allocation path. I suspect it uses kmalloc, >>> right? >> >> Yes. >> >> I took a look at the implementation and the callsites of >> memcg_kmem_charge_memcg(). It looks it is called by: >> >> * charge kmem to memcg, but it is charged to the allocator's memcg >> * allocate new slab page, charge to memcg_params.memcg >> >> I think this is the plumbing you mentioned, right? > > Maybe I have misunderstood, but you are using slab allocator. So you > would need to force it to use a different charging context than current.
Yes.
> I haven't checked deeply but this doesn't look trivial to me.
I agree. This is also what I explained to Jan and Amir in earlier discussion.
Yang
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