linux-kernel - Re: [PATCH v4 6/6] RISC-V: Free-up initrd in free_initrd

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Message-ID: <20190213064419.GA27012@infradead.org>
Date:   Tue, 12 Feb 2019 22:44:19 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Anup Patel <Anup.Patel@....com>
Cc:     Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <Atish.Patra@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Christoph Hellwig <hch@...radead.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 6/6] RISC-V: Free-up initrd in free_initrd_mem()

On Wed, Feb 13, 2019 at 06:32:24AM +0000, Anup Patel wrote:
> index 9cd583b6d1cd..c22b873de856 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -97,8 +97,9 @@ static void __init setup_initrd(void)
>  	initrd_end = 0;
>  }
>  
> -void free_initrd_mem(unsigned long start, unsigned long end)
> +void __init free_initrd_mem(unsigned long start, unsigned long end)
>  {
> +	memblock_free(__pa(start), end - start);

I'm pretty sure this should be a call to free_reserved_area instead.

All regions reserved using memblock_reserved and not freed before
initializing the MM are marked reserved and don't have valid page
counts, etc.

So we need the actions in free_reserved_area to actually make the
memory useful.  Now every other architecture except for arm64
seems to do fine without a memblock_free.  I'm not an expert on
memblock (but I've CCed one), but I guess the reason is that once
the kernel has booted we don't really care about freeing memblock
area.