linux-kernel - Re: [PATCH 1/3] memblock, nobootmem: Add memblock_virt_alloc

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Message-ID: <20140124192536.GC17156@phenom.dumpdata.com>
Date:	Fri, 24 Jan 2014 14:25:36 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	linux-kernel@...r.kernel.org, Russell King <linux@....linux.org.uk>
Subject: Re: [PATCH 1/3] memblock, nobootmem: Add memblock_virt_alloc_low()

On Fri, Jan 24, 2014 at 11:11:10AM -0800, Yinghai Lu wrote:
> The new memblock_virt APIs are used to replaced old bootmem API.
> 
> We need to allocate page below 4G for swiotlb.
> 
> That should fix regression on Andrew's system that is using swiotlb.

Please include the title of the patch that caused the regression.
I presume it is "mm/lib/swiotlb: Use memblock apis for early memory allocations"

Interestingly enough when I asked about it:

https://lkml.org/lkml/2013/11/9/280


	>> v_overflow_buffer = memblock_virt_alloc_align_nopanic(
	>> +						PAGE_ALIGN(io_tlb_overflow),
	>> +						PAGE_SIZE);
	> 
	> Does this guarantee that the pages will be allocated below 4GB?
	> 
	Yes. The memblock layer still allocates memory from lowmem. As I
	mentioned, there is no change in the behavior than what is today
	apart from just the interface change.

How did that happend? Was there another patch in the series that altered
such assumption?

> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Russell King <linux@....linux.org.uk>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> 
> ---
>  arch/arm/kernel/setup.c |    2 +-
>  include/linux/bootmem.h |   37 +++++++++++++++++++++++++++++++++++++
>  lib/swiotlb.c           |    4 ++--
>  3 files changed, 40 insertions(+), 3 deletions(-)
> 
> Index: linux-2.6/include/linux/bootmem.h
> ===================================================================
> --- linux-2.6.orig/include/linux/bootmem.h
> +++ linux-2.6/include/linux/bootmem.h
> @@ -175,6 +175,27 @@ static inline void * __init memblock_vir
>  						    NUMA_NO_NODE);
>  }
>  
> +#ifndef ARCH_LOW_ADDRESS_LIMIT
> +#define ARCH_LOW_ADDRESS_LIMIT  0xffffffffUL
> +#endif
> +
> +static inline void * __init memblock_virt_alloc_low(
> +					phys_addr_t size, phys_addr_t align)
> +{
> +	return memblock_virt_alloc_try_nid(size, align,
> +						   BOOTMEM_LOW_LIMIT,
> +						   ARCH_LOW_ADDRESS_LIMIT,
> +						   NUMA_NO_NODE);
> +}
> +static inline void * __init memblock_virt_alloc_low_nopanic(
> +					phys_addr_t size, phys_addr_t align)
> +{
> +	return memblock_virt_alloc_try_nid_nopanic(size, align,
> +						   BOOTMEM_LOW_LIMIT,
> +						   ARCH_LOW_ADDRESS_LIMIT,
> +						   NUMA_NO_NODE);
> +}
> +
>  static inline void * __init memblock_virt_alloc_from_nopanic(
>  		phys_addr_t size, phys_addr_t align, phys_addr_t min_addr)
>  {
> @@ -238,6 +259,22 @@ static inline void * __init memblock_vir
>  	return __alloc_bootmem_nopanic(size, align, BOOTMEM_LOW_LIMIT);
>  }
>  
> +static inline void * __init memblock_virt_alloc_low(
> +					phys_addr_t size, phys_addr_t align)
> +{
> +	if (!align)
> +		align = SMP_CACHE_BYTES;
> +	return __alloc_bootmem_low(size, align, BOOTMEM_LOW_LIMIT);
> +}
> +
> +static inline void * __init memblock_virt_alloc_low_nopanic(
> +					phys_addr_t size, phys_addr_t align)
> +{
> +	if (!align)
> +		align = SMP_CACHE_BYTES;
> +	return __alloc_bootmem_low_nopanic(size, align, BOOTMEM_LOW_LIMIT);
> +}
> +
>  static inline void * __init memblock_virt_alloc_from_nopanic(
>  		phys_addr_t size, phys_addr_t align, phys_addr_t min_addr)
>  {
> Index: linux-2.6/lib/swiotlb.c
> ===================================================================
> --- linux-2.6.orig/lib/swiotlb.c
> +++ linux-2.6/lib/swiotlb.c
> @@ -172,7 +172,7 @@ int __init swiotlb_init_with_tbl(char *t
>  	/*
>  	 * Get the overflow emergency buffer
>  	 */
> -	v_overflow_buffer = memblock_virt_alloc_nopanic(
> +	v_overflow_buffer = memblock_virt_alloc_low_nopanic(
>  						PAGE_ALIGN(io_tlb_overflow),
>  						PAGE_SIZE);
>  	if (!v_overflow_buffer)
> @@ -220,7 +220,7 @@ swiotlb_init(int verbose)
>  	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
>  
>  	/* Get IO TLB memory from the low pages */
> -	vstart = memblock_virt_alloc_nopanic(PAGE_ALIGN(bytes), PAGE_SIZE);
> +	vstart = memblock_virt_alloc_low_nopanic(PAGE_ALIGN(bytes), PAGE_SIZE);
>  	if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
>  		return;
>  
> Index: linux-2.6/arch/arm/kernel/setup.c
> ===================================================================
> --- linux-2.6.orig/arch/arm/kernel/setup.c
> +++ linux-2.6/arch/arm/kernel/setup.c
> @@ -717,7 +717,7 @@ static void __init request_standard_reso
>  	kernel_data.end     = virt_to_phys(_end - 1);
>  
>  	for_each_memblock(memory, region) {
> -		res = memblock_virt_alloc(sizeof(*res), 0);
> +		res = memblock_virt_alloc_low(sizeof(*res), 0);
>  		res->name  = "System RAM";
>  		res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
>  		res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
--
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