Re: [PATCH] rss_stat: Add support to detect RSS updates of external mm

From: Petr Mladek <pmladek@suse.com>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, Ioannis Ilkos <ilkos@google.com>,
	minchan@google.com, primiano@google.com, fmayer@google.com,
	hjd@google.com, joaodias@google.com, lalitm@google.com,
	rslawik@google.com, sspatil@google.com, timmurray@google.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Changbin Du <changbin.du@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Joe Perches <joe@perches.com>,
	Kees Cook <keescook@chromium.org>,
	linux-mm@kvack.org, Michal Hocko <mhocko@suse.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] rss_stat: Add support to detect RSS updates of external mm
Date: Fri, 8 Nov 2019 09:47:07 +0100	[thread overview]
Message-ID: <20191108084707.fwy6junacy4b4fld@pathway.suse.cz> (raw)
In-Reply-To: <20191107180751.GA3846@google.com>

On Thu 2019-11-07 13:07:51, Joel Fernandes wrote:
> On Wed, Nov 06, 2019 at 09:59:59AM +0100, Petr Mladek wrote:
> > On Tue 2019-11-05 21:44:51, Joel Fernandes (Google) wrote:
> > > Also vsprintf.c is refactored a bit to allow reuse of hashing code.
> > 
> > I agree with Sergey that it would make sense to move this outside
> > vsprintf.c.
> 
> I am of the opinion that its Ok to have it this way and I am not sure if
> another translation unit is worth it just for this. If we have more users,
> then yes we can consider splitting into its own translation unit at that
> time.

Fair enough. I still think that it would make sense to move the code
but I do not want to block this patch because of this.

My view is that vsprintf.c is huge and the hashing-related code
is lost there. It consists of more pieces, early_param, static key,
workqueue work.

> If Andrew Morton objects, then I'll do it since the intention was for this
> patch to go through his tree and I believe he is Ok with it this way.
> 
> > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> > > index dee8fc467fcf..401baaac1813 100644
> > > --- a/lib/vsprintf.c
> > > +++ b/lib/vsprintf.c
> > > @@ -761,11 +761,34 @@ static int __init initialize_ptr_random(void)
> > >  early_initcall(initialize_ptr_random);
> > >  
> > >  /* Maps a pointer to a 32 bit unique identifier. */
> > > +int ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
> > > +{
> > > +	const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
> > 
> > str is unused.
> 
> I believe Andrew has already fixed this in his tree.
> 
> linux-next has local variable removed now:
> 7422993b4f8e ("rss_stat-add-support-to-detect-rss-updates-of-external-mm-fix")

I see. With this fix, feel free to add:

Acked-by: Petr Mladek <pmladek@suse.com> # lib/vsprintf.c

The clean up could be done by a followup patches.

Best Regards,
Petr