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proc: export more page flags in /proc/kpageflags
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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: Wu 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@torvalds
Wu Fengguang authored and torvalds committed Jun 17, 2009
1 parent ed7ce0f commit 1779754
Showing 1 changed file with 120 additions and 32 deletions.
152 changes: 120 additions & 32 deletions fs/proc/page.c
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Original file line number Diff line number Diff line change
Expand Up @@ -72,19 +72,124 @@ static const struct file_operations proc_kpagecount_operations = {

/* 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

#define kpf_copy_bit(flags, dstpos, srcpos) (((flags >> srcpos) & 1) << dstpos)
#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_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)
Expand All @@ -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);
Expand All @@ -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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