On 04/18/2018 08:49 PM, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
More rationale? Such as "This will allow us to ... later in the series"?
> slub now needs to set page->mapping to NULL as it frees the page, just
> like slab does.
I wonder if they should be touching the mapping field, and rather not
the slab_cache field, with a comment why it has to be NULLed?
> Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> ---
> include/linux/mm_types.h | 4 ++--
> mm/slub.c | 1 +
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 41828fb34860..e97a310a6abe 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -83,7 +83,7 @@ struct page {
> /* See page-flags.h for the definition of PAGE_MAPPING_FLAGS */
> struct address_space *mapping;
>
> - void *s_mem; /* slab first object */
> + struct kmem_cache *slab_cache; /* SL[AU]B: Pointer to slab */
> atomic_t compound_mapcount; /* first tail page */
> /* page_deferred_list().next -- second tail page */
> };
> @@ -194,7 +194,7 @@ struct page {
> spinlock_t ptl;
> #endif
> #endif
> - struct kmem_cache *slab_cache; /* SL[AU]B: Pointer to slab */
> + void *s_mem; /* slab first object */
> };
>
> #ifdef CONFIG_MEMCG
> diff --git a/mm/slub.c b/mm/slub.c
> index 099925cf456a..27b6ba1c116a 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1690,6 +1690,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
> __ClearPageSlab(page);
>
> page_mapcount_reset(page);
> + page->mapping = NULL;
> if (current->reclaim_state)
> current->reclaim_state->reclaimed_slab += pages;
> memcg_uncharge_slab(page, order, s);
>
