linux-kernel - Re: [PATCH] openrisc: Reserve memblock for initrd

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Message-ID: <20200901102044.GB3562056@lianli.shorne-pla.net>
Date:   Tue, 1 Sep 2020 19:20:44 +0900
From:   Stafford Horne <shorne@...il.com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        openrisc@...ts.librecores.org
Subject: Re: [PATCH] openrisc: Reserve memblock for initrd

On Tue, Sep 01, 2020 at 08:59:24AM +0300, Mike Rapoport wrote:
> On Tue, Sep 01, 2020 at 06:21:01AM +0900, Stafford Horne wrote:
> > Recently OpenRISC added support for external initrd images, but I found
> > some instability when using larger buildroot initrd images. It turned
> > out that I forgot to reserve the memblock space for the initrd image.
> > 
> > This patch fixes the instability issue by reserving memblock space.
> > 
> > Fixes: ff6c923dbec3 ("openrisc: Add support for external initrd images")
> > Signed-off-by: Stafford Horne <shorne@...il.com>
> > ---
> >  arch/openrisc/kernel/setup.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/arch/openrisc/kernel/setup.c b/arch/openrisc/kernel/setup.c
> > index b18e775f8be3..2c8aa53cc7ba 100644
> > --- a/arch/openrisc/kernel/setup.c
> > +++ b/arch/openrisc/kernel/setup.c
> > @@ -80,6 +80,15 @@ static void __init setup_memory(void)
> >  	 */
> >  	memblock_reserve(__pa(_stext), _end - _stext);
> >  
> > +#ifdef CONFIG_BLK_DEV_INITRD
> > +	/* Then reserve the initrd, if any */
> > +	if (initrd_start && (initrd_end > initrd_start)) {
> > +		memblock_reserve(ALIGN_DOWN(__pa(initrd_start), PAGE_SIZE),
> > +			ALIGN(initrd_end, PAGE_SIZE) -
> > +			ALIGN_DOWN(initrd_start, PAGE_SIZE));
> > +	}
> 
> The core mm takes care of reserving the entrire pages for the memory
> reserved with memblock, so it is not necessary to do it here.

Thanks for the pointer

I guess what you mean is it is not required to do the page alignment.  I used
other architectures as an example and most do the alignment, I think for most
architectures this can be pulled out to generic code.

-Stafford

> > +#endif /* CONFIG_BLK_DEV_INITRD */
> > +
> >  	early_init_fdt_reserve_self();
> >  	early_init_fdt_scan_reserved_mem();
> >  
> > -- 
> > 2.26.2
> > 
> 
> -- 
> Sincerely yours,
> Mike.