On Mon, Nov 28, 2022 at 02:34:54PM -0800, Sidhartha Kumar wrote:
> Hello,
>
> One of my patches in linux-next was flagged as a Unverified Error/Warning
> with the following warning[1]:
>
> mm/hugetlb.c:2073 alloc_pool_huge_page() error: uninitialized symbol
> 'folio'.
>
> The relevant change is:
>
> - struct page *page;
> + struct folio *folio;
> int nr_nodes, node;
> gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
>
> for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
> - page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed,
> - node_alloc_noretry);
> - if (page)
> + folio = alloc_fresh_hugetlb_folio(h, gfp_mask, node,
> + nodes_allowed, node_alloc_noretry);
> + if (folio)
> break;
> }
>
> - if (!page)
> + if (!folio)
>
> It looks like I can initialize folio to NULL to avoid this error but I'm not
> sure how this would cause a regression as previously the page variable was
> unitialized as well. Please let me know if I am missing something in my
> patch or if this should be ignored.
Both the original and the new code trigger a Smatch warning. I don't
know why the kbuild-bot marks this as a new warning. Possibly that's
because the variable name has changed? The kbuild-bot is run by Intel.
The problem is obviously that Smatch doesn't know that we always enter
the loop. There are hack arounds that I could do for this, but
sometimes we dont' actually enter the loop so changing this will hide
bugs... I am conflicted on this.
regards,
dan carpenter
