mm/vmalloc: fix return value of vb_alloc if size is 0.

[RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size is 0.

Posted by hailong.liu@oppo.com 4 weeks, 1 day ago

From: "Hailong.Liu" <hailong.liu@oppo.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@oppo.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

Re: [RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size is 0.

Posted by Uladzislau Rezki 3 weeks, 5 days ago

On Fri, Apr 19, 2024 at 06:16:43PM +0800, hailong.liu@oppo.com wrote:
> From: "Hailong.Liu" <hailong.liu@oppo.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@oppo.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@gmail.com>

--
Uladzislau Rezki

Re: [RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size is 0.

Posted by Barry Song 3 weeks, 5 days ago

On Fri, Apr 19, 2024 at 6:17 PM <hailong.liu@oppo.com> wrote:
>
> From: "Hailong.Liu" <hailong.liu@oppo.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@oppo.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);

might be ZERO_SIZE_PTR.

>         }
>         order = get_order(size);
>
> --
> 2.34.1

Re: [RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size is 0.

Posted by Hailong Liu 3 weeks, 5 days ago

On Mon, 22. Apr 11:46, Barry Song wrote:
> On Fri, Apr 19, 2024 at 6:17 PM <hailong.liu@oppo.com> wrote:
> >
> > From: "Hailong.Liu" <hailong.liu@oppo.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@oppo.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);
>
> might be ZERO_SIZE_PTR.

Hi Barry,
Hi Barry, I use ERR_PTR(-EINVAL) to keep consistency with the return
value of the function alloc_vmap_area.

	if (unlikely(!size || offset_in_page(size) || !is_power_of_2(align)))
		return ERR_PTR(-EINVAL);

IMO, ZERO_SIZE_PTR is used by slab and can not be catched by IS_ERR().

--
Best Regards,
Hailong.

Re: [RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size is 0.

Posted by Barry Song 3 weeks, 4 days ago

On Mon, Apr 22, 2024 at 6:39 PM Hailong Liu <hailong.liu@oppo.com> wrote:
>
> On Mon, 22. Apr 11:46, Barry Song wrote:
> > On Fri, Apr 19, 2024 at 6:17 PM <hailong.liu@oppo.com> wrote:
> > >
> > > From: "Hailong.Liu" <hailong.liu@oppo.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@oppo.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);
> >
> > might be ZERO_SIZE_PTR.
>
> Hi Barry,
> Hi Barry, I use ERR_PTR(-EINVAL) to keep consistency with the return
> value of the function alloc_vmap_area.
>
>         if (unlikely(!size || offset_in_page(size) || !is_power_of_2(align)))
>                 return ERR_PTR(-EINVAL);
>
> IMO, ZERO_SIZE_PTR is used by slab and can not be catched by IS_ERR().

Ok. it seems not worth to change two places.

Reviewed-by: Barry Song <baohua@kernel.org>

>
> --
> Best Regards,
> Hailong.