Messages in this thread | | | Date | Thu, 15 Feb 2024 14:12:41 +0100 | Subject | Re: [PATCH net-next] page_pool: disable direct recycling based on pool->cpuid on destroy | From | Alexander Lobakin <> |
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From: Toke Høiland-Jørgensen <toke@redhat.com> Date: Thu, 15 Feb 2024 13:05:30 +0100
> Alexander Lobakin <aleksander.lobakin@intel.com> writes: > >> Now that direct recycling is performed basing on pool->cpuid when set, >> memory leaks are possible: >> >> 1. A pool is destroyed. >> 2. Alloc cache is emptied (it's done only once). >> 3. pool->cpuid is still set. >> 4. napi_pp_put_page() does direct recycling basing on pool->cpuid. >> 5. Now alloc cache is not empty, but it won't ever be freed. > > Did you actually manage to trigger this? pool->cpuid is only set for the > system page pool instance which is never destroyed; so this seems a very > theoretical concern?
To both Lorenzo and Toke:
Yes, system page pools are never destroyed, but we might latter use cpuid in non-persistent PPs. Then there will be memory leaks. I was able to trigger this by creating bpf/test_run page_pools with the cpuid set to test direct recycling of live frames.
> > I guess we could still do this in case we find other uses for setting > the cpuid; I don't think the addition of the READ_ONCE() will have any > measurable overhead on the common arches?
READ_ONCE() is cheap, but I thought it's worth mentioning in the commitmsg anyway :)
> > -Toke >
Thanks, Olek
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