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Message-ID: <ZiYwqBQCi-udlfLz@pc636>
Date: Mon, 22 Apr 2024 11:40:56 +0200
From: Uladzislau Rezki <urezki@...il.com>
To: hailong.liu@...o.com
Cc: akpm@...ux-foundation.org, urezki@...il.com, hch@...radead.org,
lstoakes@...il.com, 21cnbao@...il.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size
is 0.
On Fri, Apr 19, 2024 at 06:16:43PM +0800, hailong.liu@...o.com wrote:
> From: "Hailong.Liu" <hailong.liu@...o.com>
>
> vm_map_ram check return value of vb_alloc by IS_ERR. if
> vm_map_ram(page, 0, 0) , vb_alloc(0, GFP_KERNEL) would return NULL
> which cause kernel panic by vmap_pages_range_noflush。fix this by
> return ERR_PTR(-EINVAL) if size is 0.
>
> Signed-off-by: Hailong.Liu <hailong.liu@...o.com>
> ---
> Changes since v1 [1]:
> - Return ERR_PTR(-EINVAL) or not check IS_ERR_OR_NULL
>
> BTW, Barry suggests me that if count is 0, return directly, in my
> opinion, change return value is more resonable.
>
> [1] https://lore.kernel.org/all/84d7cd03-1cf8-401a-8edf-2524db0bd6d5@oppo.com/
>
> mm/vmalloc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index a3fedb3ee0db..c430a999805b 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2173,7 +2173,7 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
> * get_order(0) returns funny result. Just warn and terminate
> * early.
> */
> - return NULL;
> + return ERR_PTR(-EINVAL);
> }
> order = get_order(size);
>
> --
> 2.34.1
>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>
--
Uladzislau Rezki
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