Re: [PATCH] mm/vmalloc: Fix return value check for vb_alloc

[Barry Song <21cnbao@xxxxxxxxx>]

On Wed, Feb 28, 2024 at 10:34 PM Barry Song <21cnbao@xxxxxxxxx> wrote:
>
> On Wed, Feb 28, 2024 at 9:51 PM 刘海龙(LaoLiu) <liuhailong@xxxxxxxx> 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@xxxxxxxx>
> > ---
> >  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 <= VMAP_MAX_ALLOC)) {
> >                 mem = 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 = 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 == 0))
+               return NULL;
+
        if (likely(count <= VMAP_MAX_ALLOC)) {
                mem = vb_alloc(size, GFP_KERNEL);
                if (IS_ERR(mem))


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