slub: Add frozen check in __slab_alloc

Verify that objects returned from __slab_alloc come from slab pages
in the correct state.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/mm/slub.c b/mm/slub.c
index 83f258298de7..a3395c28f561 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2245,6 +2245,12 @@ redo:
 	stat(s, ALLOC_REFILL);
 
 load_freelist:
+	/*
+	 * freelist is pointing to the list of objects to be used.
+	 * page is pointing to the page from which the objects are obtained.
+	 * That page must be frozen for per cpu allocations to work.
+	 */
+	VM_BUG_ON(!c->page->frozen);
 	c->freelist = get_freepointer(s, freelist);
 	c->tid = next_tid(c->tid);
 	local_irq_restore(flags);