From: Shakeel Butt <shakeelb@xxxxxxxxxx> Subject: slub: fix unreclaimable slab stat for bulk free 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. Link: https://lkml.kernel.org/r/20210728155354.3440560-1-shakeelb@xxxxxxxxxx Fixes: 6a486c0ad4dc ("mm, sl[ou]b: improve memory accounting") Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) --- a/mm/slub.c~slub-fix-unreclaimable-slab-stat-for-bulk-free +++ a/mm/slub.c @@ -3236,6 +3236,16 @@ 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 @@ -3272,9 +3282,7 @@ int build_detached_freelist(struct kmem_ 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; } @@ -4250,13 +4258,7 @@ 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_); _
