Re: [PATCH v3 09/17] slab: Remove folio references from __do_krealloc()

[Vlastimil Babka <vbabka@suse.cz>]

On 10/24/25 22:44, Matthew Wilcox (Oracle) wrote:
> As with memcg_slab_post_charge(), we save a call to compound_head()
> for large kmallocs.  This has a slight change of behaviour in that
> non-vmalloc, non-slab, non-kmalloc pointers will now cause a NULL
> pointer dereference rather than a warning.  We could add that back if
> really needed.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

This would be another one to change for consistency as proposed to 08/17

> ---
>  mm/slub.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 100ed979312d..4e282e7782bb 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -6924,16 +6924,16 @@ __do_krealloc(const void *p, size_t new_size, unsigned long align, gfp_t flags,
>  	if (is_kfence_address(p)) {
>  		ks = orig_size = kfence_ksize(p);
>  	} else {
> -		struct folio *folio;
> +		struct page *page;
>  
> -		folio = virt_to_folio(p);
> -		if (unlikely(!folio_test_slab(folio))) {
> +		page = virt_to_page(p);
> +		if (unlikely(PageLargeKmalloc(page))) {
>  			/* Big kmalloc object */
> -			WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE);
> -			WARN_ON(p != folio_address(folio));
> -			ks = folio_size(folio);
> +			ks = page_size(page);
> +			WARN_ON(ks <= KMALLOC_MAX_CACHE_SIZE);
> +			WARN_ON(p != page_address(page));
>  		} else {
> -			s = folio_slab(folio)->slab_cache;
> +			s = page_slab(page)->slab_cache;
>  			orig_size = get_orig_size(s, (void *)p);
>  			ks = s->object_size;
>  		}