linux-kernel - Re: [GIT PULL] tracing: Fixes to bootconfig memory management

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Date:   Tue, 14 Sep 2021 14:59:53 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Linux-MM <linux-mm@...ck.org>, Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [GIT PULL] tracing: Fixes to bootconfig memory management

On Tue, 14 Sep 2021 11:01:31 -0700
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> All of these are just plain wrong:

I'll revert these, and expect Masami to address the issues you present.

Note, they do fix a real bug as shown by:

  https://lore.kernel.org/all/e5c7ce5b-93f0-b305-de32-c99d0390eb28@suse.cz/

> 
> > +static void *init_xbc_data_copy __initdata;
> > +static phys_addr_t init_xbc_data_size __initdata;
> > +               init_xbc_data_copy = copy;
> > +               init_xbc_data_size = size + 1;
> > +       memblock_free(__pa(init_xbc_data_copy), init_xbc_data_size);  
> 
> because the xbc code already saves these as xbc_data/xbc_data_size and
> that final free should just be done in xbc_destroy_all().
> 
> So this fix is pointlessly ugly to begin with.
> 
> But what I _really_ ended up reacting to was that
> 
> > +               memblock_free(__pa(copy), size + 1);  

Should we hold off until mm has fixed this issue?

-- Steve