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Message-ID: <ZnA_QFvuyABnD3ZA@pc636>
Date: Mon, 17 Jun 2024 15:50:56 +0200
From: Uladzislau Rezki <urezki@...il.com>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Uladzislau Rezki <urezki@...il.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
Vlastimil Babka <vbabka@...e.cz>, Jakub Kicinski <kuba@...nel.org>,
Julia Lawall <Julia.Lawall@...ia.fr>, linux-block@...r.kernel.org,
kernel-janitors@...r.kernel.org, bridge@...ts.linux.dev,
linux-trace-kernel@...r.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
kvm@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Nicholas Piggin <npiggin@...il.com>, netdev@...r.kernel.org,
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ecryptfs@...r.kernel.org, Neil Brown <neilb@...e.de>,
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linux-can@...r.kernel.org, Lai Jiangshan <jiangshanlai@...il.com>,
netfilter-devel@...r.kernel.org, coreteam@...filter.org
Subject: Re: [PATCH 00/14] replace call_rcu by kfree_rcu for simple
kmem_cache_free callback
On Fri, Jun 14, 2024 at 09:33:45PM +0200, Jason A. Donenfeld wrote:
> On Fri, Jun 14, 2024 at 02:35:33PM +0200, Uladzislau Rezki wrote:
> > + /* Should a destroy process be deferred? */
> > + if (s->flags & SLAB_DEFER_DESTROY) {
> > + list_move_tail(&s->list, &slab_caches_defer_destroy);
> > + schedule_delayed_work(&slab_caches_defer_destroy_work, HZ);
> > + goto out_unlock;
> > + }
>
> Wouldn't it be smoother to have the actual kmem_cache_free() function
> check to see if it's been marked for destruction and the refcount is
> zero, rather than polling every one second? I mentioned this approach
> in: https://lore.kernel.org/all/Zmo9-YGraiCj5-MI@zx2c4.com/ -
>
> I wonder if the right fix to this would be adding a `should_destroy`
> boolean to kmem_cache, which kmem_cache_destroy() sets to true. And
> then right after it checks `if (number_of_allocations == 0)
> actually_destroy()`, and likewise on each kmem_cache_free(), it
> could check `if (should_destroy && number_of_allocations == 0)
> actually_destroy()`.
>
I do not find pooling as bad way we can go with. But your proposal
sounds reasonable to me also. We can combine both "prototypes" to
one and offer.
Can you post a prototype here?
Thanks!
--
Uladzislau Rezki
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