linux-kernel - Re: [PATCH 6/6] zsmalloc: make zsmalloc portable

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Message-ID: <4F98AEC9.4080500@kernel.org>
Date:	Thu, 26 Apr 2012 11:11:21 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	undisclosed-recipients:;
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Nitin Gupta <ngupta@...are.org>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 6/6] zsmalloc: make zsmalloc portable

On 04/25/2012 03:23 PM, Minchan Kim wrote:

> The zsmalloc uses __flush_tlb_one and set_pte.
> It's very lower functions so that it makes arhcitecture dependency
> so currently zsmalloc is used by only x86.
> This patch changes them with map_vm_area and unmap_kernel_range so
> it should work all architecture.
> 
> Signed-off-by: Minchan Kim <minchan@...nel.org>
> ---
>  drivers/staging/zsmalloc/Kconfig         |    4 ----
>  drivers/staging/zsmalloc/zsmalloc-main.c |   27 +++++++++++++++++----------
>  drivers/staging/zsmalloc/zsmalloc_int.h  |    1 -
>  3 files changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/staging/zsmalloc/Kconfig b/drivers/staging/zsmalloc/Kconfig
> index a5ab720..9084565 100644
> --- a/drivers/staging/zsmalloc/Kconfig
> +++ b/drivers/staging/zsmalloc/Kconfig
> @@ -1,9 +1,5 @@
>  config ZSMALLOC
>  	tristate "Memory allocator for compressed pages"
> -	# X86 dependency is because of the use of __flush_tlb_one and set_pte
> -	# in zsmalloc-main.c.
> -	# TODO: convert these to portable functions
> -	depends on X86
>  	default n
>  	help
>  	  zsmalloc is a slab-based memory allocator designed to store
> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
> index ff089f8..cc017b1 100644
> --- a/drivers/staging/zsmalloc/zsmalloc-main.c
> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c
> @@ -442,7 +442,7 @@ static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
>  		area = &per_cpu(zs_map_area, cpu);
>  		if (area->vm)
>  			break;
> -		area->vm = alloc_vm_area(2 * PAGE_SIZE, area->vm_ptes);
> +		area->vm = alloc_vm_area(2 * PAGE_SIZE, NULL);
>  		if (!area->vm)
>  			return notifier_from_errno(-ENOMEM);
>  		break;
> @@ -696,13 +696,22 @@ void *zs_map_object(struct zs_pool *pool, void *handle)
>  	} else {
>  		/* this object spans two pages */
>  		struct page *nextp;
> +		struct page *pages[2];
> +		struct page **page_array = &pages[0];
> +		int err;
>  
>  		nextp = get_next_page(page);
>  		BUG_ON(!nextp);
>  
> +		page_array[0] = page;
> +		page_array[1] = nextp;
>  
> -		set_pte(area->vm_ptes[0], mk_pte(page, PAGE_KERNEL));
> -		set_pte(area->vm_ptes[1], mk_pte(nextp, PAGE_KERNEL));
> +		/*
> +		 * map_vm_area never fail because we already allocated
> +		 * pages for page table in alloc_vm_area.
> +		 */
> +		err = map_vm_area(area->vm, PAGE_KERNEL, &page_array);
> +		BUG_ON(err);
>  
>  		/* We pre-allocated VM area so mapping can never fail */
>  		area->vm_addr = area->vm->addr;
> @@ -730,14 +739,12 @@ void zs_unmap_object(struct zs_pool *pool, void *handle)
>  	off = obj_idx_to_offset(page, obj_idx, class->size);
>  
>  	area = &__get_cpu_var(zs_map_area);
> -	if (off + class->size <= PAGE_SIZE) {
> +	if (off + class->size <= PAGE_SIZE)
>  		kunmap_atomic(area->vm_addr);
> -	} else {
> -		set_pte(area->vm_ptes[0], __pte(0));
> -		set_pte(area->vm_ptes[1], __pte(0));
> -		__flush_tlb_one((unsigned long)area->vm_addr);
> -		__flush_tlb_one((unsigned long)area->vm_addr + PAGE_SIZE);
> -	}
> +	else
> +		unmap_kernel_range((unsigned long)area->vm->addr,
> +					PAGE_SIZE * 2);
> +


I should have export unmap_kernel_range. :(
Before that, I will look into another option to reduce IPI storm.

Thanks.

-- 
Kind regards,
Minchan Kim
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