Messages in this thread | | | Date | Mon, 22 Apr 2024 18:38:57 +0800 | From | Hailong Liu <> | Subject | Re: [RFC PATCH v2] mm/vmalloc: fix return value of vb_alloc if size is 0. |
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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.
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