On 8/17/21 11:12 AM, Sebastian Andrzej Siewior wrote:
> 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.
Right. I wondered why the checks in __pcpu_double_call_return_bool
didn't trigger. They are VM_BUG_ON() so they did trigger after enabling
DEBUG_VM.
>
> 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
>
