Re: [PATCH] mm/hugetable.c: align some prints

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Oct 26, 2020 at 05:23:43PM -0700, Mike Kravetz wrote:
> On 10/9/20 9:23 AM, Hui Su wrote:
> > in old code, it shows like:
> > Node 0 ShmemHugePages:        0 kB
> > Node 0 ShmemPmdMapped:        0 kB
> > Node 0 FileHugePages:        0 kB
> > Node 0 FilePmdMapped:        0 kB
> > Node 0 HugePages_Total:     0
> > Node 0 HugePages_Free:      0
> > Node 0 HugePages_Surp:      0
> > 
> > which is not align. So we align it.
> > 
> > Signed-off-by: Hui Su <sh_def@163.com>
> 
> Apologies for the late reply.
> 
> I assume you you just want to make the output look better.  Correct?
> 
> To be honest, I am not sure about the policy for changing the output
> of sysfs files.  My preference would be to not change the output.  Why?
> When the output is changed there is always the possibility that someone
> may have written code that depends on the current format.  It looks like
> the output has been misaligned since the day the code was first written.
> 
> This code was recently changed to use sysfs_emit_at() instead of
> sprintf().  At that time Greg noted that this also violates the sysfs
> rule of one value per file.  So, it appears there may be a bigger issue
> than alignment.
> 
> Greg,
> Is it OK to break up these sysfs files to be one value per file if they
> contained multiple values from day 1 of their existence?  I would prefer
> not to touch them in case some is depending on current format.

You should create multiple files, with a different name, and then remove
this file.  Any tool that uses sysfs should be able to handle a file
going away, don't change the format of the data in the file, otherwise
there's no way for anyone to know what is happening.

thanks,

greg k-h