linux-kernel - Re: [PATCHv3 4/8] zram: Introduce recompress sysfs knob

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20221017170850.034705ad83c54b92236d14f7@linux-foundation.org>
Date:   Mon, 17 Oct 2022 17:08:50 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv3 4/8] zram: Introduce recompress sysfs knob

On Sun,  9 Oct 2022 18:07:16 +0900 Sergey Senozhatsky <senozhatsky@...omium.org> wrote:

> Allow zram to recompress (using secondary compression streams)
> pages. We support three modes:
> 
> 1) IDLE pages recompression is activated by `idle` mode
> 
> 	echo idle > /sys/block/zram0/recompress
> 
> 2) Since there may be many idle pages user-space may pass a size
> watermark value and we will recompress IDLE pages only of equal
> or greater size:
> 
> 	echo 888 > /sys/block/zram0/recompress

It's helpful to describe the units ("bytes") here and in the
docmentation.

> 3) HUGE pages recompression is activated by `huge` mode
> 
> 	echo huge > /sys/block/zram0/recompress
> 
> 4) HUGE_IDLE pages recompression is activated by `huge_idle` mode
> 
> 	echo huge_idle > /sys/block/zram0/recompress
> 
> ...
>
> +	if (IS_ERR((void *)handle_next)) {

IS_ERR_VALUE() avoids castsing back and forth.