Re: [PATCH 17/24] mm: export stable page flags

[Wu Fengguang <fengguang.wu@intel.com>]

[corrected CC to Christoph Lameter <cl@linux-foundation.org>]

On Wed, Dec 02, 2009 at 11:12:48AM +0800, Wu, Fengguang wrote:
> Rename get_uflags() to stable_page_flags() and make it a global function
> for use in the hwpoison page flags filter, which need to compare user
> page flags with the value provided by user space.
> 
> Also move KPF_* to kernel-page-flags.h for use by user space tools.
> 
> CC: Matt Mackall <mpm@selenic.com>
> CC: Nick Piggin <npiggin@suse.de>
> CC: Christoph Lameter <clameter@sgi.com>
> CC: Andi Kleen <andi@firstfloor.org>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
>  fs/proc/page.c                    |   45 +--------------------------
>  include/linux/kernel-page-flags.h |   46 ++++++++++++++++++++++++++++
>  include/linux/page-flags.h        |    2 +
>  3 files changed, 51 insertions(+), 42 deletions(-)
> 
> --- linux-mm.orig/fs/proc/page.c	2009-11-07 20:23:59.000000000 +0800
> +++ linux-mm/fs/proc/page.c	2009-11-07 20:37:31.000000000 +0800
> @@ -8,6 +8,7 @@
>  #include <linux/proc_fs.h>
>  #include <linux/seq_file.h>
>  #include <linux/hugetlb.h>
> +#include <linux/kernel-page-flags.h>
>  #include <asm/uaccess.h>
>  #include "internal.h"
>  
> @@ -71,52 +72,12 @@ static const struct file_operations proc
>   * physical page flags.
>   */
>  
> -/* These macros are used to decouple internal flags from exported ones */
> -
> -#define KPF_LOCKED		0
> -#define KPF_ERROR		1
> -#define KPF_REFERENCED		2
> -#define KPF_UPTODATE		3
> -#define KPF_DIRTY		4
> -#define KPF_LRU			5
> -#define KPF_ACTIVE		6
> -#define KPF_SLAB		7
> -#define KPF_WRITEBACK		8
> -#define KPF_RECLAIM		9
> -#define KPF_BUDDY		10
> -
> -/* 11-20: new additions in 2.6.31 */
> -#define KPF_MMAP		11
> -#define KPF_ANON		12
> -#define KPF_SWAPCACHE		13
> -#define KPF_SWAPBACKED		14
> -#define KPF_COMPOUND_HEAD	15
> -#define KPF_COMPOUND_TAIL	16
> -#define KPF_HUGE		17
> -#define KPF_UNEVICTABLE		18
> -#define KPF_HWPOISON		19
> -#define KPF_NOPAGE		20
> -
> -#define KPF_KSM			21
> -
> -/* kernel hacking assistances
> - * WARNING: subject to change, never rely on them!
> - */
> -#define KPF_RESERVED		32
> -#define KPF_MLOCKED		33
> -#define KPF_MAPPEDTODISK	34
> -#define KPF_PRIVATE		35
> -#define KPF_PRIVATE_2		36
> -#define KPF_OWNER_PRIVATE	37
> -#define KPF_ARCH		38
> -#define KPF_UNCACHED		39
> -
>  static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
>  {
>  	return ((kflags >> kbit) & 1) << ubit;
>  }
>  
> -static u64 get_uflags(struct page *page)
> +u64 stable_page_flags(struct page *page)
>  {
>  	u64 k;
>  	u64 u;
> @@ -219,7 +180,7 @@ static ssize_t kpageflags_read(struct fi
>  		else
>  			ppage = NULL;
>  
> -		if (put_user(get_uflags(ppage), out)) {
> +		if (put_user(stable_page_flags(ppage), out)) {
>  			ret = -EFAULT;
>  			break;
>  		}
> --- linux-mm.orig/include/linux/page-flags.h	2009-11-07 20:37:27.000000000 +0800
> +++ linux-mm/include/linux/page-flags.h	2009-11-07 20:37:31.000000000 +0800
> @@ -284,6 +284,8 @@ PAGEFLAG_FALSE(HWPoison)
>  #define __PG_HWPOISON 0
>  #endif
>  
> +u64 stable_page_flags(struct page *page);
> +
>  static inline int PageUptodate(struct page *page)
>  {
>  	int ret = test_bit(PG_uptodate, &(page)->flags);
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ linux-mm/include/linux/kernel-page-flags.h	2009-11-07 20:37:31.000000000 +0800
> @@ -0,0 +1,46 @@
> +#ifndef LINUX_KERNEL_PAGE_FLAGS_H
> +#define  LINUX_KERNEL_PAGE_FLAGS_H
> +
> +/*
> + * Stable page flag bits exported to user space
> + */
> +
> +#define KPF_LOCKED		0
> +#define KPF_ERROR		1
> +#define KPF_REFERENCED		2
> +#define KPF_UPTODATE		3
> +#define KPF_DIRTY		4
> +#define KPF_LRU			5
> +#define KPF_ACTIVE		6
> +#define KPF_SLAB		7
> +#define KPF_WRITEBACK		8
> +#define KPF_RECLAIM		9
> +#define KPF_BUDDY		10
> +
> +/* 11-20: new additions in 2.6.31 */
> +#define KPF_MMAP		11
> +#define KPF_ANON		12
> +#define KPF_SWAPCACHE		13
> +#define KPF_SWAPBACKED		14
> +#define KPF_COMPOUND_HEAD	15
> +#define KPF_COMPOUND_TAIL	16
> +#define KPF_HUGE		17
> +#define KPF_UNEVICTABLE		18
> +#define KPF_HWPOISON		19
> +#define KPF_NOPAGE		20
> +
> +#define KPF_KSM			21
> +
> +/* kernel hacking assistances
> + * WARNING: subject to change, never rely on them!
> + */
> +#define KPF_RESERVED		32
> +#define KPF_MLOCKED		33
> +#define KPF_MAPPEDTODISK	34
> +#define KPF_PRIVATE		35
> +#define KPF_PRIVATE_2		36
> +#define KPF_OWNER_PRIVATE	37
> +#define KPF_ARCH		38
> +#define KPF_UNCACHED		39
> +
> +#endif /* LINUX_KERNEL_PAGE_FLAGS_H */
>