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From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>,
	Dave Hansen <dave.hansen@intel.com>, Mel Gorman <mgorman@suse.de>,
	Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
	Christoph Lameter <cl@gentwo.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Steve Capper <steve.capper@linaro.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@suse.cz>,
	Jerome Marchand <jmarchan@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH 04/16] page-flags: define PG_locked behavior on compound pages
Date: Thu, 24 Sep 2015 17:50:52 +0300	[thread overview]
Message-ID: <1443106264-78075-5-git-send-email-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <1443106264-78075-1-git-send-email-kirill.shutemov@linux.intel.com>

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.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 fs/cifs/file.c             |  8 ++++----
 include/linux/page-flags.h |  2 +-
 include/linux/pagemap.h    | 25 ++++++++-----------------
 mm/filemap.c               | 15 +++++++++------
 mm/ksm.c                   |  2 +-
 mm/memory-failure.c        |  2 +-
 mm/migrate.c               |  2 +-
 mm/shmem.c                 |  4 ++--
 mm/slub.c                  |  2 ++
 mm/swap_state.c            |  4 ++--
 mm/vmscan.c                |  2 +-
 11 files changed, 32 insertions(+), 36 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index e2a6af1508af..94f81962368c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3390,13 +3390,13 @@ 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_KERNEL);
 
 	/* give up if we can't stick it in the cache */
 	if (rc) {
-		__clear_page_locked(page);
+		__ClearPageLocked(page);
 		return rc;
 	}
 
@@ -3417,10 +3417,10 @@ 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_KERNEL)) {
-			__clear_page_locked(page);
+			__ClearPageLocked(page);
 			break;
 		}
 		list_move_tail(&page->lru, tmplist);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 1b3babe5ff69..26102813f0ac 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -244,7 +244,7 @@ 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)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a6c78e00ea96..3e95fb6a77af 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -426,18 +426,9 @@ 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)));
 }
 
@@ -490,9 +481,9 @@ 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);
@@ -511,7 +502,7 @@ 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);
 }
 
 /* 
@@ -657,17 +648,17 @@ 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;
 }
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 879747a42f6b..6cc2c17a0ca0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -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);
diff --git a/mm/ksm.c b/mm/ksm.c
index 7ee101eaacdf..bc7be0ee2080 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1884,7 +1884,7 @@ 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;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8424b64711ac..5b965e27aaae 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -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.
diff --git a/mm/migrate.c b/mm/migrate.c
index 94961f4654b7..bd19c7339f8c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1765,7 +1765,7 @@ 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: */
diff --git a/mm/shmem.c b/mm/shmem.c
index 48ce82926d93..1425863f5322 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -996,7 +996,7 @@ 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);
@@ -1188,7 +1188,7 @@ repeat:
 		}
 
 		__SetPageSwapBacked(page);
-		__set_page_locked(page);
+		__SetPageLocked(page);
 		if (sgp == SGP_WRITE)
 			__SetPageReferenced(page);
 
diff --git a/mm/slub.c b/mm/slub.c
index 999673c386d6..bda33cc4f7e4 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -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);
 }
 
diff --git a/mm/swap_state.c b/mm/swap_state.c
index d504adb7fa5f..d783872d746c 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -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.
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 38d04810e0ee..a0b8f08e6f62 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -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++;
 
-- 
2.5.1

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  parent reply	other threads:[~2015-09-24 14:51 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20150921153509.fef7ecdf313ef74307c43b65@linux-foundation.org>
2015-09-24 14:50 ` [PATCH 00/16] Refreshed page-flags patchset Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 01/16] page-flags: trivial cleanup for PageTrans* helpers Kirill A. Shutemov
2015-09-24 15:44     ` Christoph Lameter
2015-09-24 14:50   ` [PATCH 02/16] page-flags: move code around Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 03/16] page-flags: introduce page flags policies wrt compound pages Kirill A. Shutemov
2015-09-25 12:29     ` Konstantin Khlebnikov
2015-09-25 19:13       ` Kirill A. Shutemov
2015-09-28 10:02         ` Konstantin Khlebnikov
2015-09-28 11:03           ` Kirill A. Shutemov
2015-09-28 11:48             ` Konstantin Khlebnikov
2015-09-28 17:51               ` Kirill A. Shutemov
2015-09-24 14:50   ` Kirill A. Shutemov [this message]
2015-09-24 16:08     ` [PATCH 04/16] page-flags: define PG_locked behavior on " Christoph Lameter
2015-09-24 20:26       ` Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 05/16] page-flags: define behavior of FS/IO-related flags " Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 06/16] page-flags: define behavior of LRU-related " Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 07/16] page-flags: define behavior SL*B-related " Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 08/16] page-flags: define behavior of Xen-related " Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 09/16] page-flags: define PG_reserved behavior " Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 10/16] page-flags: define PG_swapbacked " Kirill A. Shutemov
2015-09-24 14:50   ` [PATCH 11/16] page-flags: define PG_swapcache " Kirill A. Shutemov
2015-09-24 14:51   ` [PATCH 12/16] page-flags: define PG_mlocked " Kirill A. Shutemov
2016-04-18 19:44     ` Sasha Levin
2016-05-18 14:02       ` Kirill A. Shutemov
2015-09-24 14:51   ` [PATCH 13/16] page-flags: define PG_uncached " Kirill A. Shutemov
2015-09-24 14:51   ` [PATCH 14/16] page-flags: define PG_uptodate " Kirill A. Shutemov
2015-09-24 14:51   ` [PATCH 15/16] page-flags: look at head page if the flag is encoded in page->mapping Kirill A. Shutemov
2015-09-24 14:51   ` [PATCH 16/16] mm: sanitize page->mapping for tail pages Kirill A. Shutemov
2015-09-25  2:20     ` Jerome Glisse
2015-09-24 16:13   ` [PATCH 00/16] Refreshed page-flags patchset Christoph Lameter
2015-09-24 20:25     ` Kirill A. Shutemov
     [not found] <010501d062df$05125160$0f36f420$@alibaba-inc.com>
2015-03-20  7:32 ` [PATCH 04/16] page-flags: define PG_locked behavior on compound pages Hillf Danton
2015-03-20  8:04   ` Kirill A. Shutemov
2015-03-19 17:08 [PATCH 00/16] Sanitize usage of ->flags and ->mapping for tail pages Kirill A. Shutemov
2015-03-19 17:08 ` [PATCH 04/16] page-flags: define PG_locked behavior on compound pages Kirill A. Shutemov
2015-03-27 15:11   ` Mateusz Krawczuk
2015-03-27 15:13   ` Mateusz Krawczuk
2015-03-27 16:37     ` Kirill A. Shutemov
2015-07-15 20:20   ` Christoph Lameter

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