Re: [PATCHv2] zram: do not waste zram_table_entry flags bits

[Minchan Kim]

On Tue, Sep 13, 2022 at 12:27:44AM +0900, Sergey Senozhatsky wrote:
> zram_table_entry::flags stores object size in the lower bits and
> zram pageflags in the upper bits. However, for some reason, we
> use 24 lower bits, while maximum zram object size is PAGE_SIZE,
> which requires PAGE_SHIFT bits (up to 16 on arm64). This wastes
> 24 - PAGE_SHIFT bits that we can use for additional zram pageflags
> instead.
> 
> Also add a BUILD_BUG_ON() to alert us should we run out of bits
> in zram_table_entry::flags.
> 
> Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>