linux-ext4 - Re: [PATCH 29/29] mm: shrinker: move shrinker-related code into a separate file

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 23 Jun 2023 14:25:54 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.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,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        intel-gfx@...ts.freedesktop.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-nfs@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org
Subject: Re: [PATCH 29/29] mm: shrinker: move shrinker-related code into a
 separate file

On (23/06/22 16:53), Qi Zheng wrote:
> +/*
> + * Remove one
> + */
> +void unregister_shrinker(struct shrinker *shrinker)
> +{
> +	struct dentry *debugfs_entry;
> +	int debugfs_id;
> +
> +	if (!(shrinker->flags & SHRINKER_REGISTERED))
> +		return;
> +
> +	shrinker_put(shrinker);
> +	wait_for_completion(&shrinker->completion_wait);
> +
> +	mutex_lock(&shrinker_mutex);
> +	list_del_rcu(&shrinker->list);

Should this function wait for RCU grace period(s) before it goes
touching shrinker fields?

> +	shrinker->flags &= ~SHRINKER_REGISTERED;
> +	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
> +		unregister_memcg_shrinker(shrinker);
> +	debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
> +	mutex_unlock(&shrinker_mutex);
> +
> +	shrinker_debugfs_remove(debugfs_entry, debugfs_id);
> +
> +	kfree(shrinker->nr_deferred);
> +	shrinker->nr_deferred = NULL;
> +}
> +EXPORT_SYMBOL(unregister_shrinker);

[..]

> +void shrinker_free(struct shrinker *shrinker)
> +{
> +	kfree(shrinker);
> +}
> +EXPORT_SYMBOL(shrinker_free);
> +
> +void unregister_and_free_shrinker(struct shrinker *shrinker)
> +{
> +	unregister_shrinker(shrinker);
> +	kfree_rcu(shrinker, rcu);
> +}

Seems like this

	unregister_shrinker();
	shrinker_free();

is not exact equivalent of this

	unregister_and_free_shrinker();