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page-flags: define PG_locked behavior on compound pages 

lock_page() must operate on the whole compound page.  It doesn't make
much sense to lock part of compound page.  Change code to use head
page's PG_locked, if tail page is passed.

This patch also gets rid of custom helper functions --
__set_page_locked() and __clear_page_locked().  They are replaced with
helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG.  Tail pages to these
helper would trigger VM_BUG_ON().

SLUB uses PG_locked as a bit spin locked.  IIUC, tail pages should never
appear there.  VM_BUG_ON() is added to make sure that this assumption is
correct.

[akpm@linux-foundation.org: fix fs/cifs/file.c]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2016-01-15 16:51:24 -08:00 committed by Linus Torvalds
parent 95ad97554a
commit 48c935ad88
11 changed files with 32 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/cifs/file.c
View File

@ -3391,13 +3391,13 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
* should have access to this page, we're safe to simply set
* PG_locked without checking it first.
*/
__set_page_locked(page);
__SetPageLocked(page);
rc = add_to_page_cache_locked(page, mapping,
page->index, gfp);
/* give up if we can't stick it in the cache */
if (rc) {
__clear_page_locked(page);
__ClearPageLocked(page);
return rc;
}
@ -3418,9 +3418,9 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
if (*bytes + PAGE_CACHE_SIZE > rsize)
break;
__set_page_locked(page);
__SetPageLocked(page);
if (add_to_page_cache_locked(page, mapping, page->index, gfp)) {
__clear_page_locked(page);
__ClearPageLocked(page);
break;
}
list_move_tail(&page->lru, tmplist);

2
include/linux/page-flags.h
View File

@ -256,7 +256,7 @@ static inline int __TestClearPage##uname(struct page *page) { return 0; }
#define TESTSCFLAG_FALSE(uname) \
TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
TESTPAGEFLAG(Locked, locked, PF_ANY)
__PAGEFLAG(Locked, locked, PF_NO_TAIL)
PAGEFLAG(Error, error, PF_ANY) TESTCLEARFLAG(Error, error, PF_ANY)
PAGEFLAG(Referenced, referenced, PF_ANY) TESTCLEARFLAG(Referenced, referenced, PF_ANY)
__SETPAGEFLAG(Referenced, referenced, PF_ANY)

25
include/linux/pagemap.h
View File

@ -433,18 +433,9 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
unsigned int flags);
extern void unlock_page(struct page *page);
static inline void __set_page_locked(struct page *page)
{
__set_bit(PG_locked, &page->flags);
}
static inline void __clear_page_locked(struct page *page)
{
__clear_bit(PG_locked, &page->flags);
}
static inline int trylock_page(struct page *page)
{
page = compound_head(page);
return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
}
@ -497,9 +488,9 @@ extern int wait_on_page_bit_killable_timeout(struct page *page,
static inline int wait_on_page_locked_killable(struct page *page)
{
if (PageLocked(page))
return wait_on_page_bit_killable(page, PG_locked);
return 0;
if (!PageLocked(page))
return 0;
return wait_on_page_bit_killable(compound_head(page), PG_locked);
}
extern wait_queue_head_t *page_waitqueue(struct page *page);
@ -518,7 +509,7 @@ static inline void wake_up_page(struct page *page, int bit)
static inline void wait_on_page_locked(struct page *page)
{
if (PageLocked(page))
wait_on_page_bit(page, PG_locked);
wait_on_page_bit(compound_head(page), PG_locked);
}
/*
@ -664,17 +655,17 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
/*
* Like add_to_page_cache_locked, but used to add newly allocated pages:
* the page is new, so we can just run __set_page_locked() against it.
* the page is new, so we can just run __SetPageLocked() against it.
*/
static inline int add_to_page_cache(struct page *page,
struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
{
int error;
__set_page_locked(page);
__SetPageLocked(page);
error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
if (unlikely(error))
__clear_page_locked(page);
__ClearPageLocked(page);
return error;
}

15
mm/filemap.c
View File

@ -682,11 +682,11 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
void *shadow = NULL;
int ret;
__set_page_locked(page);
__SetPageLocked(page);
ret = __add_to_page_cache_locked(page, mapping, offset,
gfp_mask, &shadow);
if (unlikely(ret))
__clear_page_locked(page);
__ClearPageLocked(page);
else {
/*
* The page might have been evicted from cache only
@ -809,6 +809,7 @@ EXPORT_SYMBOL_GPL(add_page_wait_queue);
*/
void unlock_page(struct page *page)
{
page = compound_head(page);
VM_BUG_ON_PAGE(!PageLocked(page), page);
clear_bit_unlock(PG_locked, &page->flags);
smp_mb__after_atomic();
@ -873,18 +874,20 @@ EXPORT_SYMBOL_GPL(page_endio);
*/
void __lock_page(struct page *page)
{
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
struct page *page_head = compound_head(page);
DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
__wait_on_bit_lock(page_waitqueue(page), &wait, bit_wait_io,
__wait_on_bit_lock(page_waitqueue(page_head), &wait, bit_wait_io,
TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(__lock_page);
int __lock_page_killable(struct page *page)
{
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
struct page *page_head = compound_head(page);
DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
return __wait_on_bit_lock(page_waitqueue(page), &wait,
return __wait_on_bit_lock(page_waitqueue(page_head), &wait,
bit_wait_io, TASK_KILLABLE);
}
EXPORT_SYMBOL_GPL(__lock_page_killable);

2
mm/ksm.c
View File

@ -1899,7 +1899,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
SetPageDirty(new_page);
__SetPageUptodate(new_page);
__set_page_locked(new_page);
__SetPageLocked(new_page);
}
return new_page;

2
mm/memory-failure.c
View File

@ -1166,7 +1166,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
/*
* We ignore non-LRU pages for good reasons.
* - PG_locked is only well defined for LRU pages and a few others
* - to avoid races with __set_page_locked()
* - to avoid races with __SetPageLocked()
* - to avoid races with __SetPageSlab*() (and more non-atomic ops)
* The check (unnecessarily) ignores LRU pages being isolated and
* walked by the page reclaim code, however that's not a big loss.

2
mm/migrate.c
View File

@ -1767,7 +1767,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
flush_tlb_range(vma, mmun_start, mmun_end);
/* Prepare a page as a migration target */
__set_page_locked(new_page);
__SetPageLocked(new_page);
SetPageSwapBacked(new_page);
/* anon mapping, we can simply copy page->mapping to the new page: */

4
mm/shmem.c
View File

@ -1085,7 +1085,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
copy_highpage(newpage, oldpage);
flush_dcache_page(newpage);
__set_page_locked(newpage);
__SetPageLocked(newpage);
SetPageUptodate(newpage);
SetPageSwapBacked(newpage);
set_page_private(newpage, swap_index);
@ -1277,7 +1277,7 @@ repeat:
}
__SetPageSwapBacked(page);
__set_page_locked(page);
__SetPageLocked(page);
if (sgp == SGP_WRITE)
__SetPageReferenced(page);

2
mm/slub.c
View File

@ -338,11 +338,13 @@ static inline int oo_objects(struct kmem_cache_order_objects x)
*/
static __always_inline void slab_lock(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
bit_spin_lock(PG_locked, &page->flags);
}
static __always_inline void slab_unlock(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
__bit_spin_unlock(PG_locked, &page->flags);
}

4
mm/swap_state.c
View File

@ -353,7 +353,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
}
/* May fail (-ENOMEM) if radix-tree node allocation failed. */
__set_page_locked(new_page);
__SetPageLocked(new_page);
SetPageSwapBacked(new_page);
err = __add_to_swap_cache(new_page, entry);
if (likely(!err)) {
@ -367,7 +367,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
}
radix_tree_preload_end();
ClearPageSwapBacked(new_page);
__clear_page_locked(new_page);
__ClearPageLocked(new_page);
/*
* add_to_swap_cache() doesn't return -EEXIST, so we can safely
* clear SWAP_HAS_CACHE flag.

2
mm/vmscan.c
View File

@ -1184,7 +1184,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* we obviously don't have to worry about waking up a process
* waiting on the page lock, because there are no references.
*/
__clear_page_locked(page);
__ClearPageLocked(page);
free_it:
nr_reclaimed++;