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Subject: Re: [PATCH] arm64: use generic free_initrd_mem()
To:     Mike Rapoport <rppt@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Mike Rapoport <rppt@linux.ibm.com>
References: <1568618488-19055-1-git-send-email-rppt@kernel.org>
From:   Laura Abbott <labbott@redhat.com>
Message-ID: <0ba20aa4-d2dd-2263-6b5f-16a5c8a39f67@redhat.com>
Date:   Mon, 16 Sep 2019 08:23:29 -0400
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On 9/16/19 8:21 AM, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
>=20
> arm64 calls memblock_free() for the initrd area in its implementation of
> free_initrd_mem(), but this call has no actual effect that late in the bo=
ot
> process. By the time initrd is freed, all the reserved memory is managed =
by
> the page allocator and the memblock.reserved is unused, so there is no
> point to update it.
>=20

People like to use memblock for keeping track of memory even if it has no
actual effect. We made this change explicitly (see 05c58752f9dc ("arm64: To=
 remove
initrd reserved area entry from memblock") That said, moving to the generic
APIs would be nice. Maybe we can find another place to update the accountin=
g?

> Without the memblock_free() call the only difference between arm64 and th=
e
> generic versions of free_initrd_mem() is the memory poisoning. Switching
> arm64 to the generic version will enable the poisoning.
>=20
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
>=20
> I've boot tested it on qemu and I've checked that kexec works.
>=20
>   arch/arm64/mm/init.c | 8 --------
>   1 file changed, 8 deletions(-)
>=20
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index f3c7952..8ad2934 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -567,14 +567,6 @@ void free_initmem(void)
>   =09unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begi=
n));
>   }
>  =20
> -#ifdef CONFIG_BLK_DEV_INITRD
> -void __init free_initrd_mem(unsigned long start, unsigned long end)
> -{
> -=09free_reserved_area((void *)start, (void *)end, 0, "initrd");
> -=09memblock_free(__virt_to_phys(start), end - start);
> -}
> -#endif
> -
>   /*
>    * Dump out memory limit information on panic.
>    */
>=20