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>
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0068e82..0a2752b 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3391,13 +3391,13 @@
* 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 @@
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);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 12ab023..32c87eb 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -256,7 +256,7 @@
#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 26eabf5..df214a4 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -433,18 +433,9 @@
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 @@
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 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 @@
/*
* 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 ff42d31..ae652de 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -682,11 +682,11 @@
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 @@
*/
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 @@
*/
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 2d162c5..643abe7 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1899,7 +1899,7 @@
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 8424b64..5b965e2 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1166,7 +1166,7 @@
/*
* 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 7890d0b..f7f345d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1767,7 +1767,7 @@
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 970ff5b..d271932 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1085,7 +1085,7 @@
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 @@
}
__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 2d0e610..b21fd24 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -338,11 +338,13 @@
*/
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 d504adb..d783872 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -353,7 +353,7 @@
}
/* 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 @@
}
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 108bd11..983e407 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1184,7 +1184,7 @@
* 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++;