Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 48c935ad authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

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: default avatarKirill 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 95ad9755

fs/cifs/file.c

+4 −4
Original line number Diff line number Diff line
@@ -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);

include/linux/page-flags.h

+1 −1
Original line number Diff line number Diff line
@@ -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)

include/linux/pagemap.h

+8 −17
Original line number Diff line number Diff line
@@ -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);

	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;

}

mm/filemap.c

+9 −6
Original line number Diff line number Diff line
@@ -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);

mm/ksm.c

+1 −1
Original line number Diff line number Diff line
@@ -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;