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From:   SeongJae Park <sj@kernel.org>
To:     Yajun Deng <yajun.deng@linux.dev>
Cc:     sj@kernel.org, akpm@linux-foundation.org, sieberf@amazon.com,
        shakeelb@google.com, foersleo@amazon.de, damon@lists.linux.dev,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/damon: fix missing damon_del_region()
Date:   Wed, 14 Sep 2022 09:52:06 +0000
Message-Id: <20220914095206.70459-1-sj@kernel.org>
In-Reply-To: <20220914093636.1184590-1-yajun.deng@linux.dev>
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Hi Yajun,

On Wed, 14 Sep 2022 17:36:36 +0800 Yajun Deng <yajun.deng@linux.dev> wrote:

> It should be called damon_del_region() before free each region, so use
> damon_destroy_region() instead of damon_free_region().

What 'damon_del_region()' does is deleting the region from target's regions
linked list so that nobody references it later after its freed.  However, as
each region is linked to one target, and as we will free the target here, the
list will also be freed.  Therefore, we don't need to worry about future
references to the region.

Anything I'm missing?


Thanks,
SJ

> 
> Fixes: f23b8eee1871 (mm/damon/core: implement region-based sampling)
> Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
> ---
>  mm/damon/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 0b1eb945c68a..e62e7ebf4b12 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -361,7 +361,7 @@ void damon_free_target(struct damon_target *t)
>  	struct damon_region *r, *next;
>  
>  	damon_for_each_region_safe(r, next, t)
> -		damon_free_region(r);
> +		damon_destroy_region(r, t);
>  	kfree(t);
>  }
>  
> -- 
> 2.25.1