linux-kernel - Re: [PATCH] mm/compaction: remove unused variable sysctl_compact

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: <486d7af3-95a3-9701-f0f9-706ff49b99d1@suse.cz>
Date:   Wed, 3 Mar 2021 18:09:18 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Pintu Kumar <pintu@...eaurora.org>, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, iamjoonsoo.kim@....com,
        sh_def@....com, mateusznosek0@...il.com, bhe@...hat.com,
        nigupta@...dia.com, yzaikin@...gle.com, keescook@...omium.org,
        mcgrof@...nel.org, mgorman@...hsingularity.net
Cc:     pintu.ping@...il.com
Subject: Re: [PATCH] mm/compaction: remove unused variable
 sysctl_compact_memory

On 3/2/21 6:56 PM, Pintu Kumar wrote:
> The sysctl_compact_memory is mostly unsed in mm/compaction.c
> It just acts as a place holder for sysctl.
> 
> Thus we can remove it from here and move the declaration directly
> in kernel/sysctl.c itself.
> This will also eliminate the extern declaration from header file.
> No functionality is broken or changed this way.
> 
> Signed-off-by: Pintu Kumar <pintu@...eaurora.org>
> Signed-off-by: Pintu Agarwal <pintu.ping@...il.com>

You should be able to remove the variable completely and set .data to NULL in
the corresponding entry. The sysctl_compaction_handler doesn't access it at all.

Then you could do the same with drop_caches. Currently
drop_caches_sysctl_handler currently writes to it, but that can be avoided using
a local variable - see how sysrq_sysctl_handler avoids the global variable and
its corresponding .data field is NULL.

Vlastimil