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From:   Uladzislau Rezki <urezki@gmail.com>
Date:   Mon, 6 Jun 2022 22:46:36 +0200
To:     Baoquan He <bhe@redhat.com>
Cc:     akpm@linux-foundation.org, npiggin@gmail.com, urezki@gmail.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/5] mm/vmalloc: remove the redundant boundary check
Message-ID: <Yp5nrJ2RnxYgGmL1@pc638.lan>
References: <20220606083909.363350-1-bhe@redhat.com>
 <20220606083909.363350-3-bhe@redhat.com>
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On Mon, Jun 06, 2022 at 04:39:06PM +0800, Baoquan He wrote:
> In function find_va_links(), when traversing the vmap_area tree, the
> comparing to check if the passed in 'va' is above or below 'tmp_va'
> is redundant, assuming both 'va' and 'tmp_va' has ->va_start <= ->va_end.
> 
> Here, to simplify the checking as code change.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  mm/vmalloc.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index b7a138ab7b79..c7e1634ff2b9 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -874,11 +874,9 @@ find_va_links(struct vmap_area *va,
>  		 * Trigger the BUG() if there are sides(left/right)
>  		 * or full overlaps.
>  		 */
> -		if (va->va_start < tmp_va->va_end &&
> -				va->va_end <= tmp_va->va_start)
> +		if (va->va_end <= tmp_va->va_start)
>  			link = &(*link)->rb_left;
> -		else if (va->va_end > tmp_va->va_start &&
> -				va->va_start >= tmp_va->va_end)
> +		else if (va->va_start >= tmp_va->va_end)
>  			link = &(*link)->rb_right;
>  		else {
>  			WARN(1, "vmalloc bug: 0x%lx-0x%lx overlaps with 0x%lx-0x%lx\n",
> -- 
> 2.34.1
> 
Make sense to me: Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

--
Uladzislau Rezki