![Russ Anderson](/assets/img/avatar_default.png)
Minor source code cleanup of page flags in mm/page_alloc.c. Move the definition of the groups of bits to page-flags.h. The purpose of this clean up is that the next patch will conditionally add a page flag to the groups. Doing that in a header file is cleaner than adding #ifdefs to the C code. Signed-off-by: Russ Anderson <rja@sgi.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
335 lines
10 KiB
C
335 lines
10 KiB
C
/*
|
|
* Macros for manipulating and testing page->flags
|
|
*/
|
|
|
|
#ifndef PAGE_FLAGS_H
|
|
#define PAGE_FLAGS_H
|
|
|
|
#include <linux/types.h>
|
|
#ifndef __GENERATING_BOUNDS_H
|
|
#include <linux/mm_types.h>
|
|
#include <linux/bounds.h>
|
|
#endif /* !__GENERATING_BOUNDS_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 on pagecache pages if they contain filesystem
|
|
* specific data (which is normally at page->private). It can be used by
|
|
* private allocations for its own usage.
|
|
*
|
|
* During initiation of disk I/O, PG_locked is set. This bit is set before I/O
|
|
* and cleared when writeback _starts_ or when read _completes_. PG_writeback
|
|
* is set before writeback starts and cleared when it finishes.
|
|
*
|
|
* PG_locked also pins a page in pagecache, and blocks truncation of the file
|
|
* while it is held.
|
|
*
|
|
* page_waitqueue(page) is a wait queue of all tasks waiting for the page
|
|
* to become unlocked.
|
|
*
|
|
* 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.
|
|
*
|
|
* PG_referenced, PG_reclaim are used for page reclaim for anonymous and
|
|
* file-backed pagecache (see mm/vmscan.c).
|
|
*
|
|
* 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...
|
|
*
|
|
* PG_buddy is set to indicate that the page is free and in the buddy system
|
|
* (see mm/page_alloc.c).
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
|
|
* locked- and dirty-page accounting.
|
|
*
|
|
* The page flags field is split into two parts, the main flags area
|
|
* which extends from the low bits upwards, and the fields area which
|
|
* extends from the high bits downwards.
|
|
*
|
|
* | FIELD | ... | FLAGS |
|
|
* N-1 ^ 0
|
|
* (NR_PAGEFLAGS)
|
|
*
|
|
* The fields area is reserved for fields mapping zone, node (for NUMA) and
|
|
* SPARSEMEM section (for variants of SPARSEMEM that require section ids like
|
|
* SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
|
|
*/
|
|
enum pageflags {
|
|
PG_locked, /* Page is locked. Don't touch. */
|
|
PG_error,
|
|
PG_referenced,
|
|
PG_uptodate,
|
|
PG_dirty,
|
|
PG_lru,
|
|
PG_active,
|
|
PG_slab,
|
|
PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
|
|
PG_arch_1,
|
|
PG_reserved,
|
|
PG_private, /* If pagecache, has fs-private data */
|
|
PG_writeback, /* Page is under writeback */
|
|
#ifdef CONFIG_PAGEFLAGS_EXTENDED
|
|
PG_head, /* A head page */
|
|
PG_tail, /* A tail page */
|
|
#else
|
|
PG_compound, /* A compound page */
|
|
#endif
|
|
PG_swapcache, /* Swap page: swp_entry_t in private */
|
|
PG_mappedtodisk, /* Has blocks allocated on-disk */
|
|
PG_reclaim, /* To be reclaimed asap */
|
|
PG_buddy, /* Page is free, on buddy lists */
|
|
#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
|
|
PG_uncached, /* Page has been mapped as uncached */
|
|
#endif
|
|
__NR_PAGEFLAGS
|
|
};
|
|
|
|
#ifndef __GENERATING_BOUNDS_H
|
|
|
|
/*
|
|
* Macros to create function definitions for page flags
|
|
*/
|
|
#define TESTPAGEFLAG(uname, lname) \
|
|
static inline int Page##uname(struct page *page) \
|
|
{ return test_bit(PG_##lname, &page->flags); }
|
|
|
|
#define SETPAGEFLAG(uname, lname) \
|
|
static inline void SetPage##uname(struct page *page) \
|
|
{ set_bit(PG_##lname, &page->flags); }
|
|
|
|
#define CLEARPAGEFLAG(uname, lname) \
|
|
static inline void ClearPage##uname(struct page *page) \
|
|
{ clear_bit(PG_##lname, &page->flags); }
|
|
|
|
#define __SETPAGEFLAG(uname, lname) \
|
|
static inline void __SetPage##uname(struct page *page) \
|
|
{ __set_bit(PG_##lname, &page->flags); }
|
|
|
|
#define __CLEARPAGEFLAG(uname, lname) \
|
|
static inline void __ClearPage##uname(struct page *page) \
|
|
{ __clear_bit(PG_##lname, &page->flags); }
|
|
|
|
#define TESTSETFLAG(uname, lname) \
|
|
static inline int TestSetPage##uname(struct page *page) \
|
|
{ return test_and_set_bit(PG_##lname, &page->flags); }
|
|
|
|
#define TESTCLEARFLAG(uname, lname) \
|
|
static inline int TestClearPage##uname(struct page *page) \
|
|
{ return test_and_clear_bit(PG_##lname, &page->flags); }
|
|
|
|
|
|
#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
|
|
SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
|
|
|
|
#define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
|
|
__SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
|
|
|
|
#define PAGEFLAG_FALSE(uname) \
|
|
static inline int Page##uname(struct page *page) \
|
|
{ return 0; }
|
|
|
|
#define TESTSCFLAG(uname, lname) \
|
|
TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
|
|
|
|
struct page; /* forward declaration */
|
|
|
|
PAGEFLAG(Locked, locked) TESTSCFLAG(Locked, locked)
|
|
PAGEFLAG(Error, error)
|
|
PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
|
|
PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
|
|
PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
|
|
PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
|
|
__PAGEFLAG(Slab, slab)
|
|
PAGEFLAG(Checked, owner_priv_1) /* Used by some filesystems */
|
|
PAGEFLAG(Pinned, owner_priv_1) TESTSCFLAG(Pinned, owner_priv_1) /* Xen */
|
|
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
|
|
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
|
|
__SETPAGEFLAG(Private, private)
|
|
|
|
/*
|
|
* Only test-and-set exist for PG_writeback. The unconditional operators are
|
|
* risky: they bypass page accounting.
|
|
*/
|
|
TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
|
|
__PAGEFLAG(Buddy, buddy)
|
|
PAGEFLAG(MappedToDisk, mappedtodisk)
|
|
|
|
/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
|
|
PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
|
|
PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */
|
|
|
|
#ifdef CONFIG_HIGHMEM
|
|
/*
|
|
* Must use a macro here due to header dependency issues. page_zone() is not
|
|
* available at this point.
|
|
*/
|
|
#define PageHighMem(__p) is_highmem(page_zone(__p))
|
|
#else
|
|
PAGEFLAG_FALSE(HighMem)
|
|
#endif
|
|
|
|
#ifdef CONFIG_SWAP
|
|
PAGEFLAG(SwapCache, swapcache)
|
|
#else
|
|
PAGEFLAG_FALSE(SwapCache)
|
|
#endif
|
|
|
|
#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
|
|
PAGEFLAG(Uncached, uncached)
|
|
#else
|
|
PAGEFLAG_FALSE(Uncached)
|
|
#endif
|
|
|
|
static inline int PageUptodate(struct page *page)
|
|
{
|
|
int ret = test_bit(PG_uptodate, &(page)->flags);
|
|
|
|
/*
|
|
* Must ensure that the data we read out of the page is loaded
|
|
* _after_ we've loaded page->flags to check for PageUptodate.
|
|
* We can skip the barrier if the page is not uptodate, because
|
|
* we wouldn't be reading anything from it.
|
|
*
|
|
* See SetPageUptodate() for the other side of the story.
|
|
*/
|
|
if (ret)
|
|
smp_rmb();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static inline void __SetPageUptodate(struct page *page)
|
|
{
|
|
smp_wmb();
|
|
__set_bit(PG_uptodate, &(page)->flags);
|
|
#ifdef CONFIG_S390
|
|
page_clear_dirty(page);
|
|
#endif
|
|
}
|
|
|
|
static inline void SetPageUptodate(struct page *page)
|
|
{
|
|
#ifdef CONFIG_S390
|
|
if (!test_and_set_bit(PG_uptodate, &page->flags))
|
|
page_clear_dirty(page);
|
|
#else
|
|
/*
|
|
* Memory barrier must be issued before setting the PG_uptodate bit,
|
|
* so that all previous stores issued in order to bring the page
|
|
* uptodate are actually visible before PageUptodate becomes true.
|
|
*
|
|
* s390 doesn't need an explicit smp_wmb here because the test and
|
|
* set bit already provides full barriers.
|
|
*/
|
|
smp_wmb();
|
|
set_bit(PG_uptodate, &(page)->flags);
|
|
#endif
|
|
}
|
|
|
|
CLEARPAGEFLAG(Uptodate, uptodate)
|
|
|
|
extern void cancel_dirty_page(struct page *page, unsigned int account_size);
|
|
|
|
int test_clear_page_writeback(struct page *page);
|
|
int test_set_page_writeback(struct page *page);
|
|
|
|
static inline void set_page_writeback(struct page *page)
|
|
{
|
|
test_set_page_writeback(page);
|
|
}
|
|
|
|
#ifdef CONFIG_PAGEFLAGS_EXTENDED
|
|
/*
|
|
* System with lots of page flags available. This allows separate
|
|
* flags for PageHead() and PageTail() checks of compound pages so that bit
|
|
* tests can be used in performance sensitive paths. PageCompound is
|
|
* generally not used in hot code paths.
|
|
*/
|
|
__PAGEFLAG(Head, head)
|
|
__PAGEFLAG(Tail, tail)
|
|
|
|
static inline int PageCompound(struct page *page)
|
|
{
|
|
return page->flags & ((1L << PG_head) | (1L << PG_tail));
|
|
|
|
}
|
|
#else
|
|
/*
|
|
* Reduce page flag use as much as possible by overlapping
|
|
* compound page flags with the flags used for page cache pages. Possible
|
|
* because PageCompound is always set for compound pages and not for
|
|
* pages on the LRU and/or pagecache.
|
|
*/
|
|
TESTPAGEFLAG(Compound, compound)
|
|
__PAGEFLAG(Head, compound)
|
|
|
|
/*
|
|
* PG_reclaim is used in combination with PG_compound to mark the
|
|
* head and tail of a compound page. This saves one page flag
|
|
* but makes it impossible to use compound pages for the page cache.
|
|
* The PG_reclaim bit would have to be used for reclaim or readahead
|
|
* if compound pages enter the page cache.
|
|
*
|
|
* PG_compound & PG_reclaim => Tail page
|
|
* PG_compound & ~PG_reclaim => Head page
|
|
*/
|
|
#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
|
|
|
|
static inline int PageTail(struct page *page)
|
|
{
|
|
return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
|
|
}
|
|
|
|
static inline void __SetPageTail(struct page *page)
|
|
{
|
|
page->flags |= PG_head_tail_mask;
|
|
}
|
|
|
|
static inline void __ClearPageTail(struct page *page)
|
|
{
|
|
page->flags &= ~PG_head_tail_mask;
|
|
}
|
|
|
|
#endif /* !PAGEFLAGS_EXTENDED */
|
|
|
|
#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
|
|
1 << PG_buddy | 1 << PG_writeback | \
|
|
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active)
|
|
|
|
/*
|
|
* Flags checked in bad_page(). Pages on the free list should not have
|
|
* these flags set. It they are, there is a problem.
|
|
*/
|
|
#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | 1 << PG_reclaim | 1 << PG_dirty)
|
|
|
|
/*
|
|
* Flags checked when a page is freed. Pages being freed should not have
|
|
* these flags set. It they are, there is a problem.
|
|
*/
|
|
#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS | 1 << PG_reserved)
|
|
|
|
/*
|
|
* Flags checked when a page is prepped for return by the page allocator.
|
|
* Pages being prepped should not have these flags set. It they are, there
|
|
* is a problem.
|
|
*/
|
|
#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | 1 << PG_reserved | 1 << PG_dirty)
|
|
|
|
#endif /* !__GENERATING_BOUNDS_H */
|
|
#endif /* PAGE_FLAGS_H */
|