linux-kernel - Re: [PATCH v2 03/47] mm: shrinker: add infrastructure for dynamically allocating shrinker

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Message-ID: <20230724122549.GA3731903@hirez.programming.kicks-ass.net>
Date:   Mon, 24 Jul 2023 14:25:49 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Qi Zheng <zhengqi.arch@...edance.com>
Cc:     akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
        vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
        brauner@...nel.org, paulmck@...nel.org, tytso@....edu,
        steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
        yujie.liu@...el.com, gregkh@...uxfoundation.org,
        muchun.song@...ux.dev, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, x86@...nel.org, kvm@...r.kernel.org,
        xen-devel@...ts.xenproject.org, linux-erofs@...ts.ozlabs.org,
        linux-f2fs-devel@...ts.sourceforge.net, cluster-devel@...hat.com,
        linux-nfs@...r.kernel.org, linux-mtd@...ts.infradead.org,
        rcu@...r.kernel.org, netdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        dm-devel@...hat.com, linux-raid@...r.kernel.org,
        linux-bcache@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-btrfs@...r.kernel.org
Subject: Re: [PATCH v2 03/47] mm: shrinker: add infrastructure for
 dynamically allocating shrinker

On Mon, Jul 24, 2023 at 05:43:10PM +0800, Qi Zheng wrote:

> +void shrinker_unregister(struct shrinker *shrinker)
> +{
> +	struct dentry *debugfs_entry;
> +	int debugfs_id;
> +
> +	if (!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))
> +		return;
> +
> +	down_write(&shrinker_rwsem);
> +	list_del(&shrinker->list);
> +	shrinker->flags &= ~SHRINKER_REGISTERED;
> +	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
> +		unregister_memcg_shrinker(shrinker);
> +	debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
> +	up_write(&shrinker_rwsem);
> +
> +	shrinker_debugfs_remove(debugfs_entry, debugfs_id);

Should there not be an rcu_barrier() right about here?

> +
> +	kfree(shrinker->nr_deferred);
> +	shrinker->nr_deferred = NULL;
> +
> +	kfree(shrinker);
> +}
> +EXPORT_SYMBOL(shrinker_unregister);