Received-SPF: pass (google.com: domain of linux-kernel+bounces-84782-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Precedence: bulk
MIME-Version: 1.0
References: <84d7cd03-1cf8-401a-8edf-2524db0bd6d5@oppo.com> <CAGsJ_4w_itxmZR7ytu7HnptQNZQzM-vAJhE_zSZrTAH1iqBV6g@mail.gmail.com>
In-Reply-To: <CAGsJ_4w_itxmZR7ytu7HnptQNZQzM-vAJhE_zSZrTAH1iqBV6g@mail.gmail.com>
From: Barry Song <21cnbao@gmail.com>
Date: Wed, 28 Feb 2024 22:39:41 +1300
Message-ID: <CAGsJ_4w+L03rPcFbLm4E5sWixkKLizB4vxR-Z6LHbqwV56vB4w@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>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Wed, Feb 28, 2024 at 10:34=E2=80=AFPM Barry Song <21cnbao@gmail.com> wro=
te:
>
> On Wed, Feb 28, 2024 at 9:51=E2=80=AFPM =E5=88=98=E6=B5=B7=E9=BE=99(LaoLi=
u) <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 in=
t
> > 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?

what about the below?

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 25a8df497255..640157221c95 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2834,6 +2834,9 @@ void *vm_map_ram(struct page **pages, unsigned
int count, int node)
        unsigned long addr;
        void *mem;

+       if (unlikely(count =3D=3D 0))
+               return NULL;
+
        if (likely(count <=3D VMAP_MAX_ALLOC)) {
                mem =3D vb_alloc(size, GFP_KERNEL);
                if (IS_ERR(mem))


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