On Fri, Oct 20, 2023 at 09:34:07AM -0700, Andrew Morton wrote:
> On Fri, 20 Oct 2023 17:13:32 +0300 Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> > Smatch complains that "hpage" can be used uninitialized:
> >
> > mm/khugepaged.c:1234 collapse_huge_page()
> > error: uninitialized symbol 'hpage'.
> >
> > Initialized it on this path.
> >
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -1062,8 +1062,10 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
> > int node = hpage_collapse_find_target_node(cc);
> > struct folio *folio;
> >
> > - if (!hpage_collapse_alloc_folio(&folio, gfp, node, &cc->alloc_nmask))
> > + if (!hpage_collapse_alloc_folio(&folio, gfp, node, &cc->alloc_nmask)) {
> > + *hpage = NULL;
> > return SCAN_ALLOC_HUGE_PAGE_FAIL;
> > + }
> >
> > if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
> > folio_put(folio);
>
> Thanks. Seems this was accidentally fixed by
>
> Author: Peter Xu <peterx@xxxxxxxxxx>
> AuthorDate: Wed Feb 22 14:52:47 2023 -0500
> Commit: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> CommitDate: Tue Mar 28 16:20:06 2023 -0700
>
> mm/khugepaged: alloc_charge_hpage() take care of mem charge errors
>
>
> Which was quite a long time ago. Are you scanning old kernel versions?
There are two error paths. Peter's patch changed the second
SCAN_CGROUP_CHARGE_FAIL error path but left the first
SCAN_ALLOC_HUGE_PAGE_FAIL error path.
To be honest, it's probably a better idea to just add a *hpage = NULL
at the start of the function.
regards,
dan carpenter
