Re: [PATCH] mm/compaction: remove unused variable sysctl_compact_memory

[pintu]

On 2021-03-03 22:39, Vlastimil Babka wrote:
> 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@xxxxxxxxxxxxxx>
> > Signed-off-by: Pintu Agarwal <pintu.ping@xxxxxxxxx>
>
> 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.

Oh yes, thank you so much for the reference.
Yes I was looking to do something similar but didn't realize that is 
possible.
I will re-submit the new patch.

And yes, I will try to explore more on drop_caches part as well.

Thanks,
Pintu