linux-kernel - Re: [PATCH 2/2] of: of_reserved_mem: mark nomap memory instead of removing

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Message-ID: <YNGr1AlWV0AYnL1d@google.com>
Date:   Tue, 22 Jun 2021 09:22:28 +0000
From:   Quentin Perret <qperret@...gle.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Dong Aisheng <aisheng.dong@....com>,
        Stephen Boyd <sboyd@...nel.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        KarimAllah Ahmed <karahmed@...zon.de>,
        linux-mm <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Dong Aisheng <dongas86@...il.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 2/2] of: of_reserved_mem: mark nomap memory instead of
 removing

On Friday 11 Jun 2021 at 11:10:36 (-0600), Rob Herring wrote:
> On Fri, Jun 11, 2021 at 7:13 AM Dong Aisheng <aisheng.dong@....com> wrote:
> >
> > Since commit 86588296acbf ("fdt: Properly handle "no-map" field in the memory region"),
> > nomap memory is changed to call memblock_mark_nomap() instead of
> > memblock_remove(). But it only changed the reserved memory with fixed
> > addr and size case in early_init_dt_reserve_memory_arch(), not
> > including the dynamical allocation by size case in
> > early_init_dt_alloc_reserved_memory_arch().
> >
> > Cc: Rob Herring <robh+dt@...nel.org>
> > Cc: devicetree@...r.kernel.org
> 
> Good practice is to Cc the people involved in referenced commits.
> Adding them now. This code is a minefield so I'd like other eyes on
> it.

Apologies for the delayed reply -- was away last week.

I've been starring at this for 15 minutes, and still can't see how it
could go wrong, so FWIW:

Reviewed-by: Quentin Perret <qperret@...gle.com>

Thanks,
Quentin

> > Signed-off-by: Dong Aisheng <aisheng.dong@....com>
> > ---
> >  drivers/of/of_reserved_mem.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> > index 367f298a83b2..ebba88395bf8 100644
> > --- a/drivers/of/of_reserved_mem.c
> > +++ b/drivers/of/of_reserved_mem.c
> > @@ -42,7 +42,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> >
> >         *res_base = base;
> >         if (nomap)
> > -               return memblock_remove(base, size);
> > +               return memblock_mark_nomap(base, size);
> >
> >         return memblock_reserve(base, size);
> >  }
> > @@ -276,7 +276,7 @@ void __init fdt_init_reserved_mem(void)
> >                                 pr_info("node %s compatible matching fail\n",
> >                                         rmem->name);
> >                                 if (nomap)
> > -                                       memblock_add(rmem->base, rmem->size);
> > +                                       memblock_clear_nomap(rmem->base, rmem->size);
> >                                 else
> >                                         memblock_free(rmem->base, rmem->size);
> >                         }
> > --
> > 2.25.1
> >