On Wed 28-07-21 08:53:54, Shakeel Butt wrote:
> SLUB uses page allocator for higher order allocations and update
> unreclaimable slab stat for such allocations. At the moment, the bulk
> free for SLUB does not share code with normal free code path for these
> type of allocations and have missed the stat update. So, fix the stat
> update by common code. The user visible impact of the bug is the
> potential of inconsistent unreclaimable slab stat visible through
> meminfo and vmstat.
>
> Fixes: 6a486c0ad4dc ("mm, sl[ou]b: improve memory accounting")
> Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
LGTM
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/slub.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 6dad2b6fda6f..03770291aa6b 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3238,6 +3238,16 @@ struct detached_freelist {
> struct kmem_cache *s;
> };
>
> +static inline void free_nonslab_page(struct page *page)
> +{
> + unsigned int order = compound_order(page);
> +
> + VM_BUG_ON_PAGE(!PageCompound(page), page);
> + kfree_hook(page_address(page));
> + mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order));
> + __free_pages(page, order);
> +}
> +
> /*
> * This function progressively scans the array with free objects (with
> * a limited look ahead) and extract objects belonging to the same
> @@ -3274,9 +3284,7 @@ int build_detached_freelist(struct kmem_cache *s, size_t size,
> if (!s) {
> /* Handle kalloc'ed objects */
> if (unlikely(!PageSlab(page))) {
> - BUG_ON(!PageCompound(page));
> - kfree_hook(object);
> - __free_pages(page, compound_order(page));
> + free_nonslab_page(page);
> p[size] = NULL; /* mark object processed */
> return size;
> }
> @@ -4252,13 +4260,7 @@ void kfree(const void *x)
>
> page = virt_to_head_page(x);
> if (unlikely(!PageSlab(page))) {
> - unsigned int order = compound_order(page);
> -
> - BUG_ON(!PageCompound(page));
> - kfree_hook(object);
> - mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B,
> - -(PAGE_SIZE << order));
> - __free_pages(page, order);
> + free_nonslab_page(page);
> return;
> }
> slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_);
> --
> 2.32.0.432.gabb21c7263-goog
--
Michal Hocko
SUSE Labs
