Re: [PATCH v3 6/6] efi: Disable mirror feature if kernelcore is not specified

From: Kefeng Wang <wangkefeng.wang@huawei.com>
To: Ard Biesheuvel <ardb@kernel.org>, Wupeng Ma <mawupeng1@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Darren Hart <dvhart@infradead.org>,
	Andy Shevchenko <andy@infradead.org>,
	Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Kees Cook <keescook@chromium.org>, <songmuchun@bytedance.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	<damien.lemoal@opensource.wdc.com>,
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	Geert Uytterhoeven <geert@linux-m68k.org>,
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	<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH v3 6/6] efi: Disable mirror feature if kernelcore is not specified
Date: Fri, 10 Jun 2022 20:15:17 +0800	[thread overview]
Message-ID: <70bd99eb-a05d-adb0-5cb8-84dcc66b674e@huawei.com> (raw)
In-Reply-To: <CAMj1kXGMHn_jsMe2WxWZ-s_QV==1tc5k=xpbNXuDbGp0qF534w@mail.gmail.com>

On 2022/6/10 19:20, Ard Biesheuvel wrote:
> On Tue, 7 Jun 2022 at 11:16, Wupeng Ma <mawupeng1@huawei.com> wrote:
>> From: Ma Wupeng <mawupeng1@huawei.com>
>>
>> If system have some mirrored memory and mirrored feature is not specified
>> in boot parameter, the basic mirrored feature will be enabled and this will
>> lead to the following situations:
>>
>> - memblock memory allocation prefers mirrored region. This may have some
>>    unexpected influence on numa affinity.
>>
>> - contiguous memory will be split into several parts if parts of them
>>    is mirrored memory via memblock_mark_mirror().
>>
>> To fix this, variable mirrored_kernelcore will be checked before calling
>> efi_find_mirror() which will enable basic mirrored feature and this
>> variable is true if kernelcore=mirror is added in the kernel parameters.
>>
>> Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
> This seems like the wrong place to do this. If mirrored memory is
> irrelevant to memblock, it should ignore the attribute. So I think
> this check belongs in mm/memblock.c instead.

Sound good,  let's add check into memblock_mark_mirror() and retain

the efi memory mirror information printing.

>
>
>> ---
>>   drivers/firmware/efi/efi.c | 3 +++
>>   include/linux/mm.h         | 2 ++
>>   mm/page_alloc.c            | 2 +-
>>   3 files changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
>> index 79c232e07de7..8a5edcb0dd82 100644
>> --- a/drivers/firmware/efi/efi.c
>> +++ b/drivers/firmware/efi/efi.c
>> @@ -454,6 +454,9 @@ void __init efi_find_mirror(void)
>>          if (!efi_enabled(EFI_MEMMAP))
>>                  return;
>>
>> +       if (!mirrored_kernelcore)
>> +               return;
>> +
>>          for_each_efi_memory_desc(md) {
>>                  unsigned long long start = md->phys_addr;
>>                  unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index bc8f326be0ce..741ac7d022c3 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -2540,6 +2540,8 @@ extern void get_pfn_range_for_nid(unsigned int nid,
>>                          unsigned long *start_pfn, unsigned long *end_pfn);
>>   extern unsigned long find_min_pfn_with_active_regions(void);
>>
>> +extern bool mirrored_kernelcore;
>> +
>>   #ifndef CONFIG_NUMA
>>   static inline int early_pfn_to_nid(unsigned long pfn)
>>   {
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index e008a3df0485..cf6f70aba787 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -356,7 +356,7 @@ static unsigned long required_kernelcore_percent __initdata;
>>   static unsigned long required_movablecore __initdata;
>>   static unsigned long required_movablecore_percent __initdata;
>>   static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
>> -static bool mirrored_kernelcore __meminitdata;
>> +bool mirrored_kernelcore __meminitdata;
>>
>>   /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
>>   int movable_zone;
>> --
>> 2.25.1
>>
> .