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From: Xishi Qiu <qiuxishi@huawei.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	"H. Peter Anvin" <hpa@zytor.com>
Cc: yeyunfeng <yeyunfeng@huawei.com>, Wenan Mao <maowenan@huawei.com>,
	Linux MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] should BIOS change the efi type when we set CONFIG_X86_RESERVE_LOW ?
Date: Mon, 23 Apr 2018 18:17:58 +0800	[thread overview]
Message-ID: <5ADDB2D6.3040703@huawei.com> (raw)
In-Reply-To: <5ACEBB47.3060300@huawei.com>

On 2018/4/12 9:49, Xishi Qiu wrote:

> Hi, I find CONFIG_X86_RESERVE_LOW=64 in my system, so trim_low_memory_range()
> will reserve low 64kb memory. But efi_free_boot_services() will free it to
> buddy system again later because BIOS set the type to EFI_BOOT_SERVICES_CODE.
> 
> Here is the log:
> ...
> efi: mem03: type=3, attr=0xf, range=[0x000000000000e000-0x0000000000010000) (0MB
> ...
> 
> 

When call memblock_is_region_reserved(), it will set md->num_pages = 0 if the
memblock region is reserved. But trim_low_memory_range() reserve the region
after efi, so this breaks the logic, and efi_free_boot_services() will free
the pages(efi code/data). That means trim_low_memory_range() has not reserve
the low memory range.

...
efi_reserve_boot_services()
...
trim_low_memory_range()
...
efi_free_boot_services()
...

Shall we move trim_low_memory_range() before efi_reserve_boot_services()?

Thanks,
Xishi Qiu

> .
> 

      reply	other threads:[~2018-04-23 10:18 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-12  1:49 [RFC] should BIOS change the efi type when we set CONFIG_X86_RESERVE_LOW ? Xishi Qiu
2018-04-23 10:17 ` Xishi Qiu [this message]

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