netdev - Re: [PATCH v4 bpf-next 12/14] bpf: Introduce bpf_mem_free_rcu() similar to kfree

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Date: Fri, 7 Jul 2023 09:45:15 +0800
From: Hou Tao <houtao@...weicloud.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: tj@...nel.org, rcu@...r.kernel.org, netdev@...r.kernel.org,
 bpf@...r.kernel.org, kernel-team@...com, daniel@...earbox.net,
 andrii@...nel.org, void@...ifault.com, paulmck@...nel.org
Subject: Re: [PATCH v4 bpf-next 12/14] bpf: Introduce bpf_mem_free_rcu()
 similar to kfree_rcu().

On 7/6/2023 11:34 AM, Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@...nel.org>
>
> Introduce bpf_mem_[cache_]free_rcu() similar to kfree_rcu().
> Unlike bpf_mem_[cache_]free() that links objects for immediate reuse into
> per-cpu free list the _rcu() flavor waits for RCU grace period and then moves
> objects into free_by_rcu_ttrace list where they are waiting for RCU
> task trace grace period to be freed into slab.
>
> The life cycle of objects:
> alloc: dequeue free_llist
> free: enqeueu free_llist
> free_rcu: enqueue free_by_rcu -> waiting_for_gp
> free_llist above high watermark -> free_by_rcu_ttrace
> after RCU GP waiting_for_gp -> free_by_rcu_ttrace
> free_by_rcu_ttrace -> waiting_for_gp_ttrace -> slab
>
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Acked-by: Hou Tao <houtao1@...wei.com>