linux-kernel - Re: [PATCH 1/2] zsmalloc: introduce zs_huge

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Message-ID: <20180209053630.GC689@jagdpanzerIV>
Date:   Fri, 9 Feb 2018 14:36:30 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH 1/2] zsmalloc: introduce zs_huge_object() function

On (02/08/18 20:10), Matthew Wilcox wrote:
[..]
> Examples::
> 
>   * Context: Any context.
>   * Context: Any context. Takes and releases the RCU lock.
>   * Context: Any context. Expects <lock> to be held by caller.
>   * Context: Process context. May sleep if @gfp flags permit.
>   * Context: Process context. Takes and releases <mutex>.
>   * Context: Softirq or process context. Takes and releases <lock>, BH-safe.
>   * Context: Interrupt context.

I assume that  <mutex>  spelling serves as a placeholder and should be
replaced with a lock name in a real comment. E.g.

	Takes and releases audit_cmd_mutex.

or should it actually be

	Takes and releases <audit_cmd_mutex>.




So below is zs_huge_object() documentation I came up with:

---

+/**
+ * zs_huge_object() - Test if a compressed object's size is too big for normal
+ *                    zspool classes and it will be stored in a huge class.
+ * @sz: Size in bytes of the compressed object.
+ *
+ * The functions checks if the object's size falls into huge_class area.
+ * We must take ZS_HANDLE_SIZE into account and test the actual size we
+ * are going to use up, because zs_malloc() unconditionally adds the
+ * handle size before it performs size_class lookup.
+ *
+ * Context: Any context.
+ *
+ * Return:
+ * * true  - The object's size is too big, it will be stored in a huge class.
+ * * false - The object will be store in normal zspool classes.
+ */
---

looks OK?

	-ss