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kernel-ark/include/linux/page-flags.h
Nick Piggin 9d41415221 [PATCH] mm: page_state comment more 
Clarify that preemption needs to be guarded against with the
__xxx_page_state functions.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 07:53:58 -08:00

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/*
* Macros for manipulating and testing page->flags
*/
#ifndef PAGE_FLAGS_H
#define PAGE_FLAGS_H
#include <linux/percpu.h>
#include <linux/cache.h>
#include <asm/pgtable.h>
/*
* Various page->flags bits:
*
* PG_reserved is set for special pages, which can never be swapped out. Some
* of them might not even exist (eg empty_bad_page)...
*
* The PG_private bitflag is set if page->private contains a valid value.
*
* During disk I/O, PG_locked is used. This bit is set before I/O and
* reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
* waiting for the I/O on this page to complete.
*
* PG_uptodate tells whether the page's contents is valid. When a read
* completes, the page becomes uptodate, unless a disk I/O error happened.
*
* For choosing which pages to swap out, inode pages carry a PG_referenced bit,
* which is set any time the system accesses that page through the (mapping,
* index) hash table. This referenced bit, together with the referenced bit
* in the page tables, is used to manipulate page->age and move the page across
* the active, inactive_dirty and inactive_clean lists.
*
* Note that the referenced bit, the page->lru list_head and the active,
* inactive_dirty and inactive_clean lists are protected by the
* zone->lru_lock, and *NOT* by the usual PG_locked bit!
*
* PG_error is set to indicate that an I/O error occurred on this page.
*
* PG_arch_1 is an architecture specific page state bit. The generic code
* guarantees that this bit is cleared for a page when it first is entered into
* the page cache.
*
* PG_highmem pages are not permanently mapped into the kernel virtual address
* space, they need to be kmapped separately for doing IO on the pages. The
* struct page (these bits with information) are always mapped into kernel
* address space...
*/
/*
* Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
* locked- and dirty-page accounting. The top eight bits of page->flags are
* used for page->zone, so putting flag bits there doesn't work.
*/
#define PG_locked 0 /* Page is locked. Don't touch. */
#define PG_error 1
#define PG_referenced 2
#define PG_uptodate 3
#define PG_dirty 4
#define PG_lru 5
#define PG_active 6
#define PG_slab 7 /* slab debug (Suparna wants this) */
#define PG_checked 8 /* kill me in 2.5.<early>. */
#define PG_arch_1 9
#define PG_reserved 10
#define PG_private 11 /* Has something at ->private */
#define PG_writeback 12 /* Page is under writeback */
#define PG_nosave 13 /* Used for system suspend/resume */
#define PG_compound 14 /* Part of a compound page */
#define PG_swapcache 15 /* Swap page: swp_entry_t in private */
#define PG_mappedtodisk 16 /* Has blocks allocated on-disk */
#define PG_reclaim 17 /* To be reclaimed asap */
#define PG_nosave_free 18 /* Free, should not be written */
#define PG_uncached 19 /* Page has been mapped as uncached */
/*
* Global page accounting. One instance per CPU. Only unsigned longs are
* allowed.
*
* - Fields can be modified with xxx_page_state and xxx_page_state_zone at
* any time safely (which protects the instance from modification by
* interrupt.
* - The __xxx_page_state variants can be used safely when interrupts are
* disabled.
* - The __xxx_page_state variants can be used if the field is only
* modified from process context and protected from preemption, or only
* modified from interrupt context. In this case, the field should be
* commented here.
*/
struct page_state {
unsigned long nr_dirty; /* Dirty writeable pages */
unsigned long nr_writeback; /* Pages under writeback */
unsigned long nr_unstable; /* NFS unstable pages */
unsigned long nr_page_table_pages;/* Pages used for pagetables */
unsigned long nr_mapped; /* mapped into pagetables.
* only modified from process context */
unsigned long nr_slab; /* In slab */
#define GET_PAGE_STATE_LAST nr_slab
/*
* The below are zeroed by get_page_state(). Use get_full_page_state()
* to add up all these.
*/
unsigned long pgpgin; /* Disk reads */
unsigned long pgpgout; /* Disk writes */
unsigned long pswpin; /* swap reads */
unsigned long pswpout; /* swap writes */
unsigned long pgalloc_high; /* page allocations */
unsigned long pgalloc_normal;
unsigned long pgalloc_dma32;
unsigned long pgalloc_dma;
unsigned long pgfree; /* page freeings */
unsigned long pgactivate; /* pages moved inactive->active */
unsigned long pgdeactivate; /* pages moved active->inactive */
unsigned long pgfault; /* faults (major+minor) */
unsigned long pgmajfault; /* faults (major only) */
unsigned long pgrefill_high; /* inspected in refill_inactive_zone */
unsigned long pgrefill_normal;
unsigned long pgrefill_dma32;
unsigned long pgrefill_dma;
unsigned long pgsteal_high; /* total highmem pages reclaimed */
unsigned long pgsteal_normal;
unsigned long pgsteal_dma32;
unsigned long pgsteal_dma;
unsigned long pgscan_kswapd_high;/* total highmem pages scanned */
unsigned long pgscan_kswapd_normal;
unsigned long pgscan_kswapd_dma32;
unsigned long pgscan_kswapd_dma;
unsigned long pgscan_direct_high;/* total highmem pages scanned */
unsigned long pgscan_direct_normal;
unsigned long pgscan_direct_dma32;
unsigned long pgscan_direct_dma;
unsigned long pginodesteal; /* pages reclaimed via inode freeing */
unsigned long slabs_scanned; /* slab objects scanned */
unsigned long kswapd_steal; /* pages reclaimed by kswapd */
unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
unsigned long pageoutrun; /* kswapd's calls to page reclaim */
unsigned long allocstall; /* direct reclaim calls */
unsigned long pgrotated; /* pages rotated to tail of the LRU */
unsigned long nr_bounce; /* pages for bounce buffers */
};
extern void get_page_state(struct page_state *ret);
extern void get_page_state_node(struct page_state *ret, int node);
extern void get_full_page_state(struct page_state *ret);
extern unsigned long read_page_state_offset(unsigned long offset);
extern void mod_page_state_offset(unsigned long offset, unsigned long delta);
extern void __mod_page_state_offset(unsigned long offset, unsigned long delta);
#define read_page_state(member) \
read_page_state_offset(offsetof(struct page_state, member))
#define mod_page_state(member, delta) \
mod_page_state_offset(offsetof(struct page_state, member), (delta))
#define __mod_page_state(member, delta) \
__mod_page_state_offset(offsetof(struct page_state, member), (delta))
#define inc_page_state(member) mod_page_state(member, 1UL)
#define dec_page_state(member) mod_page_state(member, 0UL - 1)
#define add_page_state(member,delta) mod_page_state(member, (delta))
#define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))
#define __inc_page_state(member) __mod_page_state(member, 1UL)
#define __dec_page_state(member) __mod_page_state(member, 0UL - 1)
#define __add_page_state(member,delta) __mod_page_state(member, (delta))
#define __sub_page_state(member,delta) __mod_page_state(member, 0UL - (delta))
#define page_state(member) (*__page_state(offsetof(struct page_state, member)))
#define state_zone_offset(zone, member) \
({ \
unsigned offset; \
if (is_highmem(zone)) \
offset = offsetof(struct page_state, member##_high); \
else if (is_normal(zone)) \
offset = offsetof(struct page_state, member##_normal); \
else if (is_dma32(zone)) \
offset = offsetof(struct page_state, member##_dma32); \
else \
offset = offsetof(struct page_state, member##_dma); \
offset; \
})
#define __mod_page_state_zone(zone, member, delta) \
do { \
__mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
} while (0)
#define mod_page_state_zone(zone, member, delta) \
do { \
mod_page_state_offset(state_zone_offset(zone, member), (delta)); \
} while (0)
/*
* Manipulation of page state flags
*/
#define PageLocked(page) \
test_bit(PG_locked, &(page)->flags)
#define SetPageLocked(page) \
set_bit(PG_locked, &(page)->flags)
#define TestSetPageLocked(page) \
test_and_set_bit(PG_locked, &(page)->flags)
#define ClearPageLocked(page) \
clear_bit(PG_locked, &(page)->flags)
#define TestClearPageLocked(page) \
test_and_clear_bit(PG_locked, &(page)->flags)
#define PageError(page) test_bit(PG_error, &(page)->flags)
#define SetPageError(page) set_bit(PG_error, &(page)->flags)
#define ClearPageError(page) clear_bit(PG_error, &(page)->flags)
#define PageReferenced(page) test_bit(PG_referenced, &(page)->flags)
#define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
#define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
#define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags)
#ifndef SetPageUptodate
#define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags)
#endif
#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
#define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)
#define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags)
#define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags)
#define __ClearPageDirty(page) __clear_bit(PG_dirty, &(page)->flags)
#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
#define PageLRU(page) test_bit(PG_lru, &(page)->flags)
#define SetPageLRU(page) set_bit(PG_lru, &(page)->flags)
#define ClearPageLRU(page) clear_bit(PG_lru, &(page)->flags)
#define __ClearPageLRU(page) __clear_bit(PG_lru, &(page)->flags)
#define PageActive(page) test_bit(PG_active, &(page)->flags)
#define SetPageActive(page) set_bit(PG_active, &(page)->flags)
#define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
#define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
#define PageSlab(page) test_bit(PG_slab, &(page)->flags)
#define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags)
#define __ClearPageSlab(page) __clear_bit(PG_slab, &(page)->flags)
#ifdef CONFIG_HIGHMEM
#define PageHighMem(page) is_highmem(page_zone(page))
#else
#define PageHighMem(page) 0 /* needed to optimize away at compile time */
#endif
#define PageChecked(page) test_bit(PG_checked, &(page)->flags)
#define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
#define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
#define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
#define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
#define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags)
#define SetPagePrivate(page) set_bit(PG_private, &(page)->flags)
#define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags)
#define PagePrivate(page) test_bit(PG_private, &(page)->flags)
#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
#define SetPageWriteback(page) \
do { \
if (!test_and_set_bit(PG_writeback, \
&(page)->flags)) \
inc_page_state(nr_writeback); \
} while (0)
#define TestSetPageWriteback(page) \
({ \
int ret; \
ret = test_and_set_bit(PG_writeback, \
&(page)->flags); \
if (!ret) \
inc_page_state(nr_writeback); \
ret; \
})
#define ClearPageWriteback(page) \
do { \
if (test_and_clear_bit(PG_writeback, \
&(page)->flags)) \
dec_page_state(nr_writeback); \
} while (0)
#define TestClearPageWriteback(page) \
({ \
int ret; \
ret = test_and_clear_bit(PG_writeback, \
&(page)->flags); \
if (ret) \
dec_page_state(nr_writeback); \
ret; \
})
#define PageNosave(page) test_bit(PG_nosave, &(page)->flags)
#define SetPageNosave(page) set_bit(PG_nosave, &(page)->flags)
#define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
#define ClearPageNosave(page) clear_bit(PG_nosave, &(page)->flags)
#define TestClearPageNosave(page) test_and_clear_bit(PG_nosave, &(page)->flags)
#define PageNosaveFree(page) test_bit(PG_nosave_free, &(page)->flags)
#define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
#define ClearPageNosaveFree(page) clear_bit(PG_nosave_free, &(page)->flags)
#define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags)
#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
#define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
#define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
#define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
#define PageCompound(page) test_bit(PG_compound, &(page)->flags)
#define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags)
#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
#ifdef CONFIG_SWAP
#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
#define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
#define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
#else
#define PageSwapCache(page) 0
#endif
#define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
#define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
struct page; /* forward declaration */
int test_clear_page_dirty(struct page *page);
int test_clear_page_writeback(struct page *page);
int test_set_page_writeback(struct page *page);
static inline void clear_page_dirty(struct page *page)
{
test_clear_page_dirty(page);
}
static inline void set_page_writeback(struct page *page)
{
test_set_page_writeback(page);
}
#endif /* PAGE_FLAGS_H */
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