Re: [PATCH v3] mm: cma: support sysfs

[Minchan Kim]

On Wed, Mar 03, 2021 at 10:09:57PM -0800, Andrew Morton wrote:
> On Wed, 3 Mar 2021 17:38:12 -0800 Minchan Kim <minchan@xxxxxxxxxx> wrote:
> 
> > > >  #endif
> > > >  	char name[CMA_MAX_NAME];
> > > > +#ifdef CONFIG_CMA_SYSFS
> > > > +	struct cma_stat	*stat;
> > > > +#endif
> > > >  };
> > > 
> > > Why aren't the stat fields simply placed directly into struct cma_stat?
> > 
> > It have a related long discussion.
> > https://lore.kernel.org/linux-mm/YCIoHBGELFWAyfMi@xxxxxxxxx/
> > https://lore.kernel.org/linux-mm/YCLLKDEQ4NYqb5Y5@xxxxxxxxx/
> > 
> > TLDR - Greg really want to see kobject stuff working as dynamic
> > property.
> 
> Please add to changelog?

Sure.

> 
> > > 
> > > ?
> > > 
> > > > +	if (!cma_stats) {
> > > > +		pr_err("failed to create cma_stats\n");
> > > 
> > > Probably unneeded - the ENOMEM stack backtrace will point straight here.
> > 
> > I failed to find the point you mentioned to print backtrace.
> > Where code do you mean to dump the backtrace?
> 
> The thing which __GFP_NOWARN disables.

Got the point.