slub: add back check for free nonslab objects

After commit f227f0faf63b ("slub: fix unreclaimable slab stat for bulk
free"), the check for free nonslab page is replaced by VM_BUG_ON_PAGE,
which only check with CONFIG_DEBUG_VM enabled, but this config may
impact performance, so it only for debug.

Commit 0937502af7c9 ("slub: Add check for kfree() of non slab objects.")
add the ability, which should be needed in any configs to catch the
invalid free, they even could be potential issue, eg, memory corruption,
use after free and double free, so replace VM_BUG_ON_PAGE to
WARN_ON_ONCE, add object address printing to help use to debug the
issue.

Link: https://lkml.kernel.org/r/20210930070214.61499-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rienjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slub.c b/mm/slub.c
index d8f7734..b6a1790 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3522,7 +3522,9 @@ static inline void free_nonslab_page(struct page *page, void *object)
 {
        unsigned int order = compound_order(page);
 
-       VM_BUG_ON_PAGE(!PageCompound(page), page);
+       if (WARN_ON_ONCE(!PageCompound(page)))
+               pr_warn_once("object pointer: 0x%p\n", object);
+
        kfree_hook(object);
        mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order));
        __free_pages(page, order);