linux-kernel - Re: [PATCH v8 12/17] zsmalloc: introduce new object mapping API

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Message-ID: <20250224090154.7Xlsipmu@linutronix.de>
Date: Mon, 24 Feb 2025 10:01:54 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Yosry Ahmed <yosry.ahmed@...ux.dev>,
	Hillf Danton <hdanton@...a.com>, Kairui Song <ryncsn@...il.com>,
	Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 12/17] zsmalloc: introduce new object mapping API

On 2025-02-22 07:25:43 [+0900], Sergey Senozhatsky wrote:
> index 03710d71d022..1288a4120855 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1377,6 +1377,135 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
>  }
>  EXPORT_SYMBOL_GPL(zs_unmap_object);
>  
> +void *zs_obj_read_begin(struct zs_pool *pool, unsigned long handle,
> +			void *local_copy)
> +{
> +	struct zspage *zspage;
> +	struct zpdesc *zpdesc;
> +	unsigned long obj, off;
> +	unsigned int obj_idx;
> +	struct size_class *class;
> +	void *addr;
> +
> +	WARN_ON(in_interrupt());

This macro is deprecated. Could you come up with something else like
!in_task() if needed?

> +	/* Guarantee we can get zspage from handle safely */
> +	read_lock(&pool->lock);
> +	obj = handle_to_obj(handle);
> +	obj_to_location(obj, &zpdesc, &obj_idx);
> +	zspage = get_zspage(zpdesc);
…

Sebastian