Re: [PATCH v4 35/35] mm, slub: convert kmem_cpu_slab protection to local_lock

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2021-08-17 10:37:48 [+0200], Vlastimil Babka wrote:
> OK reproduced. Thanks, will investigate.

With the local_lock at the top, the needed alignment gets broken for dbl
cmpxchg. On RT it was working ;)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index b5bcac29b979c..cd14aa1f9bc3c 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -42,9 +42,9 @@ enum stat_item {
 	NR_SLUB_STAT_ITEMS };
 
 struct kmem_cache_cpu {
-	local_lock_t lock;	/* Protects the fields below except stat */
 	void **freelist;	/* Pointer to next available object */
 	unsigned long tid;	/* Globally unique transaction id */
+	local_lock_t lock;	/* Protects the fields below except stat */
 	struct page *page;	/* The slab from which we are allocating */
 #ifdef CONFIG_SLUB_CPU_PARTIAL
 	struct page *partial;	/* Partially allocated frozen slabs */

Sebastian