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From: Barry Song <21cnbao@gmail.com>
Date: Wed, 28 Feb 2024 22:34:06 +1300
Message-ID: <CAGsJ_4w_itxmZR7ytu7HnptQNZQzM-vAJhE_zSZrTAH1iqBV6g@mail.gmail.com>
Subject: Re: [PATCH] mm/vmalloc: Fix return value check for vb_alloc
To: =?UTF-8?B?5YiY5rW36b6ZKExhb0xpdSk=?= <liuhailong@oppo.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>, "urezki@gmail.com" <urezki@gmail.com>, 
	"hch@infradead.org" <hch@infradead.org>, "lstoakes@gmail.com" <lstoakes@gmail.com>, 
	"linux-mm@kvack.org" <linux-mm@kvack.org>, 
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Wed, Feb 28, 2024 at 9:51=E2=80=AFPM =E5=88=98=E6=B5=B7=E9=BE=99(LaoLiu)=
 <liuhailong@oppo.com> wrote:
>
> If vm_map_ram(page, 0, 0) would cause panic by vmap_pages_range_noflush, =
so
> change IS_ERR to IS_ERR_OR_NULL to fix this.
>
> Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
> ---
>  mm/vmalloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index d12a17fc0c17..109732006cf7 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2387,7 +2387,7 @@ void *vm_map_ram(struct page **pages, unsigned int
> count, int node)
>
>         if (likely(count <=3D VMAP_MAX_ALLOC)) {
>                 mem =3D vb_alloc(size, GFP_KERNEL);
> -               if (IS_ERR(mem))
> +               if (IS_ERR_OR_NULL(mem))

it seems the only case for vb_alloc to return NULL is size =3D 0, isn't
it a bug of
caller?

>                         return NULL;
>                 addr =3D (unsigned long)mem;
>         } else {
> --
> 2.34.1

Thanks
Barry