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Message-ID: <9ee16679-969d-460b-af4a-9ad5a6a1ebcf@kernel.org>
Date: Mon, 27 Apr 2026 15:08:27 +0200
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Subject: Re: [PATCH 4/8] mm/slab: introduce kfree_rcu_nolock()
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To: "Harry Yoo (Oracle)" <harry@kernel.org>,
 Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@gentwo.org>, David Rientjes <rientjes@google.com>,
 Roman Gushchin <roman.gushchin@linux.dev>, Hao Li <hao.li@linux.dev>,
 Alexei Starovoitov <ast@kernel.org>, Uladzislau Rezki <urezki@gmail.com>,
 "Paul E . McKenney" <paulmck@kernel.org>,
 Frederic Weisbecker <frederic@kernel.org>,
 Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
 Joel Fernandes <joelagnelf@nvidia.com>, Josh Triplett
 <josh@joshtriplett.org>, Boqun Feng <boqun@kernel.org>,
 Zqiang <qiang.zhang@linux.dev>, Steven Rostedt <rostedt@goodmis.org>,
 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
 Lai Jiangshan <jiangshanlai@gmail.com>, rcu@vger.kernel.org,
 linux-mm@kvack.org
References: <20260416091022.36823-1-harry@kernel.org>
 <20260416091022.36823-5-harry@kernel.org>
From: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
In-Reply-To: <20260416091022.36823-5-harry@kernel.org>
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On 4/16/26 11:10, Harry Yoo (Oracle) wrote:
> +#ifndef CONFIG_KVFREE_RCU_BATCHED
> +void kvfree_call_rcu_head(struct rcu_head *head, void *ptr, bool allow_spin)
> +{
> +	if (!allow_spin) {
> +		struct kfree_rcu_cpu *krcp;
> +
> +		guard(preempt)();
> +
> +		krcp = this_cpu_ptr(&krc);
> +		if (llist_add((struct llist_node *)head, &krcp->defer_head))
> +			irq_work_queue(&krcp->defer_free);
> +		return;
> +	}
> +

Given "allow_spin" is compile-time constant, it would make more sense to
have different functions for each variant rather than calling a common one
with the extra param?

>  	if (head) {
>  		kasan_record_aux_stack(ptr);
>  		call_rcu(head, kvfree_rcu_cb);