Re: [PATCH v2 3/4] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails

[Barry Song <21cnbao@gmail.com>]

On Wed, Jul 31, 2024 at 6:48 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 7/31/24 12:44 PM, Tetsuo Handa wrote:
> > On 2024/07/31 19:29, Vlastimil Babka wrote:
> >>> @@ -827,8 +827,10 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
> >>>  {
> >>>     size_t bytes;
> >>>
> >>> -   if (unlikely(check_mul_overflow(n, size, &bytes)))
> >>> +   if (unlikely(check_mul_overflow(n, size, &bytes))) {
> >>> +           BUG_ON(flags & __GFP_NOFAIL);
> >>
> >> Shouldn't we produce some kind of warning also in the no-NOFAIL case?
> >> Returning a NULL completely silently feels wrong.
> >
> > Doesn't embedding macros like BUG_ON() into inline functions needlessly bloat
> > the kernel size? I think we can call a non-inlined function (that is marked
> > as EXPORT_SYMBOL()) for emitting warning.
>
> Hm yeah we could probably make the whole function non-inline as it results
> in a call anyway.

Although this might save some code footprint,  we will result in two
calls for users of
kvmalloc_array_node_noprof() with both Tetsuo's and your proposal?