Re: [PATCH 1/2] mm/zsmalloc: don't hold locks of all pages when free_zspage()

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (24/02/27 03:02), Chengming Zhou wrote:
[..]
> @@ -978,10 +974,11 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
>  		pages[i] = page;
>  	}
>  
> -	create_page_chain(class, zspage, pages);
>  	init_zspage(class, zspage);
>  	zspage->pool = pool;
>  	zspage->class = class->index;
> +	/* RCU set_zspage() after zspage initialized. */
> +	create_page_chain(class, zspage, pages);

So this hasn't been tested, has it?

init_zspage() does not like to be invoked before create_page_chain(),
because we haven't setup required pointers yet.

So when init_zspage() calls get_first_page() it gets NULL zspage->first_page
which we then use in is_first_page(first_page)->PagePrivate(page). As far as
I can tell.