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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Andrea Arcangeli <aarcange@redhat.com>,
	Avi Kivity <avi@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
	Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@elte.hu>,
	akpm@linux-foundation.org,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	David Miller <davem@davemloft.net>,
	Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@suse.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH 09/28] mm: Move anon_vma ref out from under CONFIG_KSM
Date: Mon, 07 Jun 2010 13:07:03 +0200	[thread overview]
Message-ID: <20100607111407.216849162@chello.nl> (raw)
In-Reply-To: 20100607110654.606530953@chello.nl

[-- Attachment #1: mm-anon_vma-ref.patch --]
[-- Type: text/plain, Size: 4203 bytes --]

We need an anon_vma refcount for preemptible anon_vma->lock.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/rmap.h |   40 ++++------------------------------------
 mm/rmap.c            |   10 ++++------
 2 files changed, 8 insertions(+), 42 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -27,18 +27,15 @@
 struct anon_vma {
 	spinlock_t lock;	/* Serialize access to vma list */
 	struct anon_vma *root;	/* Root of this anon_vma tree */
-#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
-
 	/*
-	 * The external_refcount is taken by either KSM or page migration
-	 * to take a reference to an anon_vma when there is no
+	 * The refcount is taken on an anon_vma when there is no
 	 * guarantee that the vma of page tables will exist for
 	 * the duration of the operation. A caller that takes
 	 * the reference is responsible for clearing up the
 	 * anon_vma if they are the last user on release
 	 */
-	atomic_t external_refcount;
-#endif
+	atomic_t refcount;
+
 	/*
 	 * NOTE: the LSB of the head.next is set by
 	 * mm_take_all_locks() _after_ taking the above lock. So the
@@ -71,41 +68,12 @@ struct anon_vma_chain {
 };
 
 #ifdef CONFIG_MMU
-#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
-static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
-{
-	atomic_set(&anon_vma->external_refcount, 0);
-}
-
-static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
-{
-	return atomic_read(&anon_vma->external_refcount);
-}
-
 static inline void get_anon_vma(struct anon_vma *anon_vma)
 {
-	atomic_inc(&anon_vma->external_refcount);
+	atomic_inc(&anon_vma->refcount);
 }
 
 void put_anon_vma(struct anon_vma *);
-#else
-static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
-{
-}
-
-static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
-{
-	return 0;
-}
-
-static inline void get_anon_vma(struct anon_vma *anon_vma)
-{
-}
-
-static inline void put_anon_vma(struct anon_vma *anon_vma)
-{
-}
-#endif /* CONFIG_KSM */
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -267,7 +267,7 @@ static void anon_vma_unlink(struct anon_
 	list_del(&anon_vma_chain->same_anon_vma);
 
 	/* We must garbage collect the anon_vma if it's empty */
-	empty = list_empty(&anon_vma->head) && !anonvma_external_refcount(anon_vma);
+	empty = list_empty(&anon_vma->head) && !atomic_read(&anon_vma->refcount);
 	anon_vma_unlock(anon_vma);
 
 	if (empty) {
@@ -297,7 +297,7 @@ static void anon_vma_ctor(void *data)
 	struct anon_vma *anon_vma = data;
 
 	spin_lock_init(&anon_vma->lock);
-	anonvma_external_refcount_init(anon_vma);
+	atomic_set(&anon_vma->refcount, 0);
 	INIT_LIST_HEAD(&anon_vma->head);
 }
 
@@ -1391,7 +1391,6 @@ int try_to_munlock(struct page *page)
 		return try_to_unmap_file(page, TTU_MUNLOCK);
 }
 
-#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
 /*
  * Drop an anon_vma refcount, freeing the anon_vma and anon_vma->root
  * if necessary.  Be careful to do all the tests under the lock.  Once
@@ -1400,7 +1399,7 @@ int try_to_munlock(struct page *page)
  */
 void put_anon_vma(struct anon_vma *anon_vma)
 {
-	if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) {
+	if (atomic_dec_and_lock(&anon_vma->refcount, &anon_vma->root->lock)) {
 		struct anon_vma *root = anon_vma->root;
 		int empty = list_empty(&anon_vma->head);
 		int last_root_user = 0;
@@ -1411,7 +1410,7 @@ void put_anon_vma(struct anon_vma *anon_
 		 * the refcount on the root and check if we need to free it.
 		 */
 		if (empty && anon_vma != root) {
-			last_root_user = atomic_dec_and_test(&root->external_refcount);
+			last_root_user = atomic_dec_and_test(&root->refcount);
 			root_empty = list_empty(&root->head);
 		}
 		anon_vma_unlock(anon_vma);
@@ -1423,7 +1422,6 @@ void put_anon_vma(struct anon_vma *anon_
 		}
 	}
 }
-#endif
 
 #ifdef CONFIG_MIGRATION
 /*



  parent reply	other threads:[~2010-06-07 11:23 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-07 11:06 [PATCH 00/28] mm: preemptibility -v3 Peter Zijlstra
2010-06-07 11:06 ` [PATCH 01/28] powerpc: Use call_rcu_sched() for pagetables Peter Zijlstra
2010-06-07 11:06 ` [PATCH 02/28] mm: Improve page_lock_anon_vma() comment Peter Zijlstra
2010-06-09 10:50   ` Mel Gorman
2010-06-07 11:06 ` [PATCH 03/28] rename anon_vma_lock to vma_lock_anon_vma Peter Zijlstra
2010-06-07 15:01   ` Peter Zijlstra
2010-06-09 10:59   ` Mel Gorman
2010-06-07 11:06 ` [PATCH 04/28] change direct call of spin_lock(anon_vma->lock) to inline function Peter Zijlstra
2010-06-07 11:06 ` [PATCH 05/28] track the root (oldest) anon_vma Peter Zijlstra
2010-06-07 11:07 ` [PATCH 06/28] always lock " Peter Zijlstra
2010-06-07 11:07 ` [PATCH 07/28] extend KSM refcounts to the anon_vma root Peter Zijlstra
2010-06-09 10:55   ` Mel Gorman
2010-06-07 11:07 ` [PATCH 08/28] mm: Rename drop_anon_vma to put_anon_vma Peter Zijlstra
2010-06-07 11:07 ` Peter Zijlstra [this message]
2010-06-09 11:05   ` [PATCH 09/28] mm: Move anon_vma ref out from under CONFIG_KSM Mel Gorman
2010-06-07 11:07 ` [PATCH 10/28] mm: Make use of the anon_vma ref count Peter Zijlstra
2010-06-09 13:22   ` Mel Gorman
2010-06-09 13:32     ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 11/28] mm: Preemptible mmu_gather Peter Zijlstra
2010-06-07 11:07 ` [PATCH 12/28] powerpc: " Peter Zijlstra
2010-06-07 11:07 ` [PATCH 13/28] sparc: " Peter Zijlstra
2010-06-07 11:07 ` [PATCH 14/28] s390: preemptible mmu_gather Peter Zijlstra
2010-06-07 11:07 ` [PATCH 15/28] arm: Preemptible mmu_gather Peter Zijlstra
2010-06-07 11:07 ` [PATCH 16/28] sh: " Peter Zijlstra
2010-06-07 11:38   ` Peter Zijlstra
2010-06-07 11:07 ` [PATCH 17/28] um: " Peter Zijlstra
2010-06-07 11:07 ` [PATCH 18/28] ia64: " Peter Zijlstra
2010-06-07 11:07 ` [PATCH 19/28] mm, powerpc: Move the RCU page-table freeing into generic code Peter Zijlstra
2010-06-07 11:07 ` [PATCH 20/28] sparc64: Kill page table quicklists Peter Zijlstra
2010-06-07 11:07 ` [PATCH 21/28] sparc64: Use RCU page table freeing Peter Zijlstra
2010-06-07 11:07 ` [PATCH 22/28] sparc64: Add support for _PAGE_SPECIAL Peter Zijlstra
2010-06-07 11:07 ` [PATCH 23/28] sparc64: Implement get_user_pages_fast() Peter Zijlstra
2010-06-07 11:07 ` [PATCH 24/28] lockdep, mutex: Provide mutex_lock_nest_lock Peter Zijlstra
2010-06-07 11:07 ` [PATCH 25/28] mutex: Provide mutex_is_contended Peter Zijlstra
2010-06-07 11:07 ` [PATCH 26/28] mm: Convert i_mmap_lock and anon_vma->lock to mutexes Peter Zijlstra
2010-06-07 11:07 ` [PATCH 27/28] mm: Extended batches for generic mmu_gather Peter Zijlstra
2010-06-07 11:07 ` [PATCH 28/28] mm: Optimize page_lock_anon_vma() fast-path Peter Zijlstra
2010-06-07 13:57 ` [PATCH 00/28] mm: preemptibility -v3 Sam Ravnborg
2010-06-07 15:02   ` Peter Zijlstra
2010-06-07 16:36 ` Andi Kleen
2010-06-07 16:39   ` Peter Zijlstra
2010-06-10  1:45 ` Zhang, Yanmin
2010-06-10  6:52   ` Peter Zijlstra
2010-06-10  6:59     ` Zhang, Yanmin
2010-06-21 10:21       ` Peter Zijlstra
2010-06-24  9:55         ` Peter Zijlstra
2010-06-29  7:40           ` Zhang, Yanmin
2010-06-29  7:48             ` Peter Zijlstra

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