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Date: Fri, 16 Feb 2024 16:08:46 -0800
From: Kees Cook <keescook@chromium.org>
To: Kent Overstreet <kent.overstreet@linux.dev>
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Subject: Re: [PATCH v3 13/35] lib: add allocation tagging support for memory
 allocation profiling
Message-ID: <202402161607.0208EB45C@keescook>
References: <20240212213922.783301-1-surenb@google.com>
 <20240212213922.783301-14-surenb@google.com>
 <202402121433.5CC66F34B@keescook>
 <lvrwtp73y2upktswswekhhilrp2i742tmhcxi2c4gayyn24qd2@hdktbg3qutgb>
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In-Reply-To: <lvrwtp73y2upktswswekhhilrp2i742tmhcxi2c4gayyn24qd2@hdktbg3qutgb>

On Fri, Feb 16, 2024 at 06:26:06PM -0500, Kent Overstreet wrote:
> On Mon, Feb 12, 2024 at 02:40:12PM -0800, Kees Cook wrote:
> > On Mon, Feb 12, 2024 at 01:38:59PM -0800, Suren Baghdasaryan wrote:
> > > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > > index ffe8f618ab86..da68a10517c8 100644
> > > --- a/include/linux/sched.h
> > > +++ b/include/linux/sched.h
> > > @@ -770,6 +770,10 @@ struct task_struct {
> > >  	unsigned int			flags;
> > >  	unsigned int			ptrace;
> > >  
> > > +#ifdef CONFIG_MEM_ALLOC_PROFILING
> > > +	struct alloc_tag		*alloc_tag;
> > > +#endif
> > 
> > Normally scheduling is very sensitive to having anything early in
> > task_struct. I would suggest moving this the CONFIG_SCHED_CORE ifdef
> > area.
> 
> This is even hotter than the scheduler members; we actually do want it
> up front.

It is? I would imagine the scheduler would touch stuff more than the
allocator, but whatever works. :)

-- 
Kees Cook