Re: [PATCH v2 2/2] kfence: Alloc kfence_pool after system startup

[Tianchen Ding]

On 2022/3/7 07:52, Marco Elver wrote:
> On Sat, 5 Mar 2022 at 15:49, Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx> wrote:
> [...]
> > +static int kfence_init_late(void)
> > +{
> > +       const unsigned long nr_pages = KFENCE_POOL_SIZE / PAGE_SIZE;
> > +       struct page *pages;
> > +
> > +       pages = alloc_contig_pages(nr_pages, GFP_KERNEL, first_online_node, NULL);
>
> > mm/kfence/core.c:836:17: error: implicit declaration of function ‘alloc_contig_pages’ [-Werror=implicit-function-declaration]
>
> This doesn't build without CMA. See ifdef CONFIG_CONTIG_ALLOC in
> gfp.h, which declares alloc_contig_pages.
>
> Will alloc_pages() work as you expect? If so, perhaps only use
> alloc_contig_pages() #ifdef CONFIG_CONTIG_ALLOC.

alloc_pages() will be fine. We could free "tail" pages after inited.
Will send v3 soon.

> Thanks,
> -- Marco