Commit 17797549 authored by Wu Fengguang's avatar Wu Fengguang Committed by Linus Torvalds
Browse files

proc: export more page flags in /proc/kpageflags 



Export all page flags faithfully in /proc/kpageflags.

	11. KPF_MMAP		(pseudo flag) memory mapped page
	12. KPF_ANON		(pseudo flag) memory mapped page (anonymous)
	13. KPF_SWAPCACHE	page is in swap cache
	14. KPF_SWAPBACKED	page is swap/RAM backed
	15. KPF_COMPOUND_HEAD	(*)
	16. KPF_COMPOUND_TAIL	(*)
	17. KPF_HUGE		hugeTLB pages
	18. KPF_UNEVICTABLE	page is in the unevictable LRU list
	19. KPF_HWPOISON(TBD)	hardware detected corruption
	20. KPF_NOPAGE		(pseudo flag) no page frame at the address
	32-39.			more obscure flags for kernel developers

	(*) For compound pages, exporting _both_ head/tail info enables
	    users to tell where a compound page starts/ends, and its order.

The accompanying page-types tool will handle the details like decoupling
overloaded flags and hiding obscure flags to normal users.

Thanks to KOSAKI and Andi for their valuable recommendations!

Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ed7ce0f1

fs/proc/page.c

+120 −32
Original line number Diff line number Diff line
@@ -84,7 +84,112 @@ static const struct file_operations proc_kpagecount_operations = { 
#define KPF_RECLAIM		9

#define KPF_BUDDY		10



#define kpf_copy_bit(flags, dstpos, srcpos) (((flags >> srcpos) & 1) << dstpos)

/* 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_NOPAGE		20



/* 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 k;

	u64 u;



	/*

	 * pseudo flag: KPF_NOPAGE

	 * it differentiates a memory hole from a page with no flags

	 */

	if (!page)

		return 1 << KPF_NOPAGE;



	k = page->flags;

	u = 0;



	/*

	 * pseudo flags for the well known (anonymous) memory mapped pages

	 *

	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the

	 * simple test in page_mapped() is not enough.

	 */

	if (!PageSlab(page) && page_mapped(page))

		u |= 1 << KPF_MMAP;

	if (PageAnon(page))

		u |= 1 << KPF_ANON;



	/*

	 * compound pages: export both head/tail info

	 * they together define a compound page's start/end pos and order

	 */

	if (PageHead(page))

		u |= 1 << KPF_COMPOUND_HEAD;

	if (PageTail(page))

		u |= 1 << KPF_COMPOUND_TAIL;

	if (PageHuge(page))

		u |= 1 << KPF_HUGE;



	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);



	/*

	 * Caveats on high order pages:

	 * PG_buddy will only be set on the head page; SLUB/SLQB do the same

	 * for PG_slab; SLOB won't set PG_slab at all on compound pages.

	 */

	u |= kpf_copy_bit(k, KPF_SLAB,		PG_slab);

	u |= kpf_copy_bit(k, KPF_BUDDY,		PG_buddy);



	u |= kpf_copy_bit(k, KPF_ERROR,		PG_error);

	u |= kpf_copy_bit(k, KPF_DIRTY,		PG_dirty);

	u |= kpf_copy_bit(k, KPF_UPTODATE,	PG_uptodate);

	u |= kpf_copy_bit(k, KPF_WRITEBACK,	PG_writeback);



	u |= kpf_copy_bit(k, KPF_LRU,		PG_lru);

	u |= kpf_copy_bit(k, KPF_REFERENCED,	PG_referenced);

	u |= kpf_copy_bit(k, KPF_ACTIVE,	PG_active);

	u |= kpf_copy_bit(k, KPF_RECLAIM,	PG_reclaim);



	u |= kpf_copy_bit(k, KPF_SWAPCACHE,	PG_swapcache);

	u |= kpf_copy_bit(k, KPF_SWAPBACKED,	PG_swapbacked);



#ifdef CONFIG_UNEVICTABLE_LRU

	u |= kpf_copy_bit(k, KPF_UNEVICTABLE,	PG_unevictable);

	u |= kpf_copy_bit(k, KPF_MLOCKED,	PG_mlocked);

#endif



#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR

	u |= kpf_copy_bit(k, KPF_UNCACHED,	PG_uncached);

#endif



	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);

	u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,	PG_mappedtodisk);

	u |= kpf_copy_bit(k, KPF_PRIVATE,	PG_private);

	u |= kpf_copy_bit(k, KPF_PRIVATE_2,	PG_private_2);

	u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE,	PG_owner_priv_1);

	u |= kpf_copy_bit(k, KPF_ARCH,		PG_arch_1);



	return u;

};



static ssize_t kpageflags_read(struct file *file, char __user *buf,

			     size_t count, loff_t *ppos)
@@ -94,7 +199,6 @@ static ssize_t kpageflags_read(struct file *file, char __user *buf, 
	unsigned long src = *ppos;

	unsigned long pfn;

	ssize_t ret = 0;

	u64 kflags, uflags;



	pfn = src / KPMSIZE;

	count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
@@ -106,24 +210,8 @@ static ssize_t kpageflags_read(struct file *file, char __user *buf, 
			ppage = pfn_to_page(pfn);

		else

			ppage = NULL;

		if (!ppage)

			kflags = 0;

		else

			kflags = ppage->flags;



		uflags = kpf_copy_bit(kflags, KPF_LOCKED, PG_locked) |

			kpf_copy_bit(kflags, KPF_ERROR, PG_error) |

			kpf_copy_bit(kflags, KPF_REFERENCED, PG_referenced) |

			kpf_copy_bit(kflags, KPF_UPTODATE, PG_uptodate) |

			kpf_copy_bit(kflags, KPF_DIRTY, PG_dirty) |

			kpf_copy_bit(kflags, KPF_LRU, PG_lru) |

			kpf_copy_bit(kflags, KPF_ACTIVE, PG_active) |

			kpf_copy_bit(kflags, KPF_SLAB, PG_slab) |

			kpf_copy_bit(kflags, KPF_WRITEBACK, PG_writeback) |

			kpf_copy_bit(kflags, KPF_RECLAIM, PG_reclaim) |

			kpf_copy_bit(kflags, KPF_BUDDY, PG_buddy);



		if (put_user(uflags, out)) {



		if (put_user(get_uflags(ppage), out)) {

			ret = -EFAULT;

			break;

		}

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