[PATCH 7/8] mm: Convert anon_vma->lock to a mutex

Peter Zijlstra
2011-03-02T18:01:18Z

[-- Attachment #1: peter_zijlstra-mm-anon_vma-lock_to_mutexes.patch --]
[-- Type: text/plain, Size: 7741 bytes --]

Straight fwd conversion of anon_vma->lock to a mutex.

Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/huge_mm.h | 8 ++------
include/linux/mmu_notifier.h | 2 +-
include/linux/rmap.h | 14 +++++++-------
mm/huge_memory.c | 4 ++--
mm/mmap.c | 10 +++++-----
mm/rmap.c | 8 ++++----
6 files changed, 21 insertions(+), 25 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -7,7 +7,7 @@
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
#include <linux/memcontrol.h>

/*
@@ -26,7 +26,7 @@
*/
struct anon_vma {
struct anon_vma *root; /* Root of this anon_vma tree */
- spinlock_t lock; /* Serialize access to vma list */
+ struct mutex mutex; /* Serialize access to vma list */
/*
* The refcount is taken on an anon_vma when there is no
* guarantee that the vma of page tables will exist for
@@ -64,7 +64,7 @@ struct anon_vma_chain {
struct vm_area_struct *vma;
struct anon_vma *anon_vma;
struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
- struct list_head same_anon_vma; /* locked by anon_vma->lock */
+ struct list_head same_anon_vma; /* locked by anon_vma->mutex */
};

#ifdef CONFIG_MMU
@@ -93,24 +93,24 @@ static inline void vma_lock_anon_vma(str
{
struct anon_vma *anon_vma = vma->anon_vma;
if (anon_vma)
- spin_lock(&anon_vma->root->lock);
+ mutex_lock(&anon_vma->root->mutex);
}

static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
{
struct anon_vma *anon_vma = vma->anon_vma;
if (anon_vma)
- spin_unlock(&anon_vma->root->lock);
+ mutex_unlock(&anon_vma->root->mutex);
}

static inline void anon_vma_lock(struct anon_vma *anon_vma)
{
- spin_lock(&anon_vma->root->lock);
+ mutex_lock(&anon_vma->root->mutex);
}

static inline void anon_vma_unlock(struct anon_vma *anon_vma)
{
- spin_unlock(&anon_vma->root->lock);
+ mutex_unlock(&anon_vma->root->mutex);
}

/*
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -25,7 +25,7 @@
* mm->mmap_sem
* page->flags PG_locked (lock_page)
* mapping->i_mmap_mutex
- * anon_vma->lock
+ * anon_vma->mutex
* mm->page_table_lock or pte_lock
* zone->lru_lock (in mark_page_accessed, isolate_lru_page)
* swap_lock (in swap_duplicate, swap_info_get)
@@ -39,7 +39,7 @@
*
* (code doesn't rely on that order so it could be switched around)
* ->tasklist_lock
- * anon_vma->lock (memory_failure, collect_procs_anon)
+ * anon_vma->mutex (memory_failure, collect_procs_anon)
* pte map lock
*/

@@ -306,7 +306,7 @@ static void anon_vma_ctor(void *data)
{
struct anon_vma *anon_vma = data;

- spin_lock_init(&anon_vma->lock);
+ mutex_init(&anon_vma->mutex);
atomic_set(&anon_vma->refcount, 0);
INIT_LIST_HEAD(&anon_vma->head);
}
@@ -1129,7 +1129,7 @@ int try_to_unmap_one(struct page *page,
/*
* We need mmap_sem locking, Otherwise VM_LOCKED check makes
* unstable result and race. Plus, We can't wait here because
- * we now hold anon_vma->lock or mapping->i_mmap_mutex.
+ * we now hold anon_vma->mutex or mapping->i_mmap_mutex.
* if trylock failed, the page remain in evictable lru and later
* vmscan could retry to move the page to unevictable lru if the
* page is actually mlocked.
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c
+++ linux-2.6/mm/mmap.c
@@ -2523,15 +2523,15 @@ static void vm_lock_anon_vma(struct mm_s
* The LSB of head.next can't change from under us
* because we hold the mm_all_locks_mutex.
*/
- spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
+ mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem);
/*
* We can safely modify head.next after taking the
- * anon_vma->root->lock. If some other vma in this mm shares
+ * anon_vma->root->mutex. If some other vma in this mm shares
* the same anon_vma we won't take it again.
*
* No need of atomic instructions here, head.next
* can't change from under us thanks to the
- * anon_vma->root->lock.
+ * anon_vma->root->mutex.
*/
if (__test_and_set_bit(0, (unsigned long *)
&anon_vma->root->head.next))
@@ -2580,7 +2580,7 @@ static void vm_lock_mapping(struct mm_st
* vma in this mm is backed by the same anon_vma or address_space.
*
* We can take all the locks in random order because the VM code
- * taking i_mmap_mutex or anon_vma->lock outside the mmap_sem never
+ * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
* takes more than one of them in a row. Secondly we're protected
* against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
*
@@ -2636,7 +2636,7 @@ static void vm_unlock_anon_vma(struct an
*
* No need of atomic instructions here, head.next
* can't change from under us until we release the
- * anon_vma->root->lock.
+ * anon_vma->root->mutex.
*/
if (!__test_and_clear_bit(0, (unsigned long *)
&anon_vma->root->head.next))
Index: linux-2.6/include/linux/mmu_notifier.h
===================================================================
--- linux-2.6.orig/include/linux/mmu_notifier.h
+++ linux-2.6/include/linux/mmu_notifier.h
@@ -150,7 +150,7 @@ struct mmu_notifier_ops {
* Therefore notifier chains can only be traversed when either
*
* 1. mmap_sem is held.
- * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->lock).
+ * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->mutex).
* 3. No other concurrent thread can access the list (release)
*/
struct mmu_notifier {
Index: linux-2.6/mm/huge_memory.c
===================================================================
--- linux-2.6.orig/mm/huge_memory.c
+++ linux-2.6/mm/huge_memory.c
@@ -1128,7 +1128,7 @@ static int __split_huge_page_splitting(s
* We can't temporarily set the pmd to null in order
* to split it, the pmd must remain marked huge at all
* times or the VM won't take the pmd_trans_huge paths
- * and it won't wait on the anon_vma->root->lock to
+ * and it won't wait on the anon_vma->root->mutex to
* serialize against split_huge_page*.
*/
pmdp_splitting_flush_notify(vma, address, pmd);
@@ -1315,7 +1315,7 @@ static int __split_huge_page_map(struct
return ret;
}

-/* must be called with anon_vma->root->lock hold */
+/* must be called with anon_vma->root->mutex hold */
static void __split_huge_page(struct page *page,
struct anon_vma *anon_vma)
{
Index: linux-2.6/include/linux/huge_mm.h
===================================================================
--- linux-2.6.orig/include/linux/huge_mm.h
+++ linux-2.6/include/linux/huge_mm.h
@@ -91,12 +91,8 @@ extern void __split_huge_page_pmd(struct
#define wait_split_huge_page(__anon_vma, __pmd) \
do { \
pmd_t *____pmd = (__pmd); \
- spin_unlock_wait(&(__anon_vma)->root->lock); \
- /* \
- * spin_unlock_wait() is just a loop in C and so the \
- * CPU can reorder anything around it. \
- */ \
- smp_mb(); \
+ anon_vma_lock(__anon_vma); \
+ anon_vma_unlock(__anon_vma); \
BUG_ON(pmd_trans_splitting(*____pmd) || \
pmd_trans_huge(*____pmd)); \
} while (0)