linux-kernel - Re: [PATCH v2 13/17] x86/setup: simplify initrd relocation and reservation

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Message-ID: <20200805042024.GT10792@MiWiFi-R3L-srv>
Date:   Wed, 5 Aug 2020 12:20:24 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christoph Hellwig <hch@....de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Emil Renner Berthing <kernel@...il.dk>,
        Ingo Molnar <mingo@...hat.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Max Filippov <jcmvbkbc@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michal Simek <monstr@...str.eu>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Russell King <linux@...linux.org.uk>,
        Stafford Horne <shorne@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        clang-built-linux@...glegroups.com,
        iommu@...ts.linux-foundation.org, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-c6x-dev@...ux-c6x.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-mm@...ck.org, linux-riscv@...ts.infradead.org,
        linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org, linuxppc-dev@...ts.ozlabs.org,
        openrisc@...ts.librecores.org, sparclinux@...r.kernel.org,
        uclinux-h8-devel@...ts.sourceforge.jp, x86@...nel.org
Subject: Re: [PATCH v2 13/17] x86/setup: simplify initrd relocation and
 reservation

On 08/02/20 at 07:35pm, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
> 
> Currently, initrd image is reserved very early during setup and then it
> might be relocated and re-reserved after the initial physical memory
> mapping is created. The "late" reservation of memblock verifies that mapped
> memory size exceeds the size of initrd, the checks whether the relocation
                                          ~ then?
> required and, if yes, relocates inirtd to a new memory allocated from
> memblock and frees the old location.
> 
> The check for memory size is excessive as memblock allocation will anyway
> fail if there is not enough memory. Besides, there is no point to allocate
> memory from memblock using memblock_find_in_range() + memblock_reserve()
> when there exists memblock_phys_alloc_range() with required functionality.
> 
> Remove the redundant check and simplify memblock allocation.
> 
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> ---
>  arch/x86/kernel/setup.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index a3767e74c758..d8de4053c5e8 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -262,16 +262,12 @@ static void __init relocate_initrd(void)
>  	u64 area_size     = PAGE_ALIGN(ramdisk_size);
>  
>  	/* We need to move the initrd down into directly mapped mem */
> -	relocated_ramdisk = memblock_find_in_range(0, PFN_PHYS(max_pfn_mapped),
> -						   area_size, PAGE_SIZE);
> -
> +	relocated_ramdisk = memblock_phys_alloc_range(area_size, PAGE_SIZE, 0,
> +						      PFN_PHYS(max_pfn_mapped));
>  	if (!relocated_ramdisk)
>  		panic("Cannot find place for new RAMDISK of size %lld\n",
>  		      ramdisk_size);
>  
> -	/* Note: this includes all the mem currently occupied by
> -	   the initrd, we rely on that fact to keep the data intact. */
> -	memblock_reserve(relocated_ramdisk, area_size);
>  	initrd_start = relocated_ramdisk + PAGE_OFFSET;
>  	initrd_end   = initrd_start + ramdisk_size;
>  	printk(KERN_INFO "Allocated new RAMDISK: [mem %#010llx-%#010llx]\n",
> @@ -298,13 +294,13 @@ static void __init early_reserve_initrd(void)
>  
>  	memblock_reserve(ramdisk_image, ramdisk_end - ramdisk_image);
>  }
> +
>  static void __init reserve_initrd(void)
>  {
>  	/* Assume only end is not page aligned */
>  	u64 ramdisk_image = get_ramdisk_image();
>  	u64 ramdisk_size  = get_ramdisk_size();
>  	u64 ramdisk_end   = PAGE_ALIGN(ramdisk_image + ramdisk_size);
> -	u64 mapped_size;
>  
>  	if (!boot_params.hdr.type_of_loader ||
>  	    !ramdisk_image || !ramdisk_size)
> @@ -312,12 +308,6 @@ static void __init reserve_initrd(void)
>  
>  	initrd_start = 0;
>  
> -	mapped_size = memblock_mem_size(max_pfn_mapped);
> -	if (ramdisk_size >= (mapped_size>>1))
> -		panic("initrd too large to handle, "
> -		       "disabling initrd (%lld needed, %lld available)\n",
> -		       ramdisk_size, mapped_size>>1);

Reviewed-by: Baoquan He <bhe@...hat.com>

> -
>  	printk(KERN_INFO "RAMDISK: [mem %#010llx-%#010llx]\n", ramdisk_image,
>  			ramdisk_end - 1);
>  
> -- 
> 2.26.2
>