On 09/16/2019 07:25 PM, Mike Rapoport wrote:
> (added linux-arch)
>
> On Mon, Sep 16, 2019 at 08:23:29AM -0400, Laura Abbott wrote:
>> On 9/16/19 8:21 AM, Mike Rapoport wrote:
>>> From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
>>>
>>> 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 boot
>>> 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.
>>>
>>
>> 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 accounting?
>
> Any other place in arch/arm64 would make it messy because it would have to
> duplicate keepinitrd logic.
>
> We could put the memblock_free() in the generic free_initrd_mem() with
> something like:
>
> diff --git a/init/initramfs.c b/init/initramfs.c
> index c47dad0..403c6a0 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -531,6 +531,10 @@ void __weak free_initrd_mem(unsigned long start,
> unsigned long end)
> {
> free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
> "initrd");
> +
> +#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
> + memblock_free(__virt_to_phys(start), end - start);
> +#endif
> }
This makes sense.
>
> #ifdef CONFIG_KEXEC_CORE
>
>
> Then powerpc and s390 folks will also be able to track the initrd memory :)
Sure.
>
>>> Without the memblock_free() call the only difference between arm64 and the
>>> generic versions of free_initrd_mem() is the memory poisoning. Switching
>>> arm64 to the generic version will enable the poisoning.
>>>
>>> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
>>> ---
>>>
>>> I've boot tested it on qemu and I've checked that kexec works.
>>>
>>> arch/arm64/mm/init.c | 8 --------
>>> 1 file changed, 8 deletions(-)
>>>
>>> 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)
>>> unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begin));
>>> }
>>> -#ifdef CONFIG_BLK_DEV_INITRD
>>> -void __init free_initrd_mem(unsigned long start, unsigned long end)
>>> -{
>>> - free_reserved_area((void *)start, (void *)end, 0, "initrd");
>>> - memblock_free(__virt_to_phys(start), end - start);
>>> -}
>>> -#endif
>>> -
>>> /*
>>> * Dump out memory limit information on panic.
>>> */
>>>
>>
>
