Merge branch 'merge' into next

Brings in various bug fixes from 3.6-rcX

8 files changed, 135 insertions, 128 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 6b4718e2ee34..b41823cc05e6 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -39,12 +39,6 @@ DEFINE_SPINLOCK(bdi_lock);
 LIST_HEAD(bdi_list);
 LIST_HEAD(bdi_pending_list);
 
-static struct task_struct *sync_supers_tsk;
-static struct timer_list sync_supers_timer;
-
-static int bdi_sync_supers(void *);
-static void sync_supers_timer_fn(unsigned long);
-
 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
 {
 	if (wb1 < wb2) {
@@ -250,12 +244,6 @@ static int __init default_bdi_init(void)
 {
 	int err;
 
-	sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers");
-	BUG_ON(IS_ERR(sync_supers_tsk));
-
-	setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
-	bdi_arm_supers_timer();
-
 	err = bdi_init(&default_backing_dev_info);
 	if (!err)
 		bdi_register(&default_backing_dev_info, NULL, "default");
@@ -270,46 +258,6 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi)
 	return wb_has_dirty_io(&bdi->wb);
 }
 
-/*
- * kupdated() used to do this. We cannot do it from the bdi_forker_thread()
- * or we risk deadlocking on ->s_umount. The longer term solution would be
- * to implement sync_supers_bdi() or similar and simply do it from the
- * bdi writeback thread individually.
- */
-static int bdi_sync_supers(void *unused)
-{
-	set_user_nice(current, 0);
-
-	while (!kthread_should_stop()) {
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule();
-
-		/*
-		 * Do this periodically, like kupdated() did before.
-		 */
-		sync_supers();
-	}
-
-	return 0;
-}
-
-void bdi_arm_supers_timer(void)
-{
-	unsigned long next;
-
-	if (!dirty_writeback_interval)
-		return;
-
-	next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies;
-	mod_timer(&sync_supers_timer, round_jiffies_up(next));
-}
-
-static void sync_supers_timer_fn(unsigned long unused)
-{
-	wake_up_process(sync_supers_tsk);
-	bdi_arm_supers_timer();
-}
-
 static void wakeup_timer_fn(unsigned long data)
 {
 	struct backing_dev_info *bdi = (struct backing_dev_info *)data;
diff --git a/mm/compaction.c b/mm/compaction.c
index e78cb9688421..7fcd3a52e68d 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -51,6 +51,47 @@ static inline bool migrate_async_suitable(int migratetype)
 }
 
 /*
+ * Compaction requires the taking of some coarse locks that are potentially
+ * very heavily contended. Check if the process needs to be scheduled or
+ * if the lock is contended. For async compaction, back out in the event
+ * if contention is severe. For sync compaction, schedule.
+ *
+ * Returns true if the lock is held.
+ * Returns false if the lock is released and compaction should abort
+ */
+static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
+				      bool locked, struct compact_control *cc)
+{
+	if (need_resched() || spin_is_contended(lock)) {
+		if (locked) {
+			spin_unlock_irqrestore(lock, *flags);
+			locked = false;
+		}
+
+		/* async aborts if taking too long or contended */
+		if (!cc->sync) {
+			if (cc->contended)
+				*cc->contended = true;
+			return false;
+		}
+
+		cond_resched();
+		if (fatal_signal_pending(current))
+			return false;
+	}
+
+	if (!locked)
+		spin_lock_irqsave(lock, *flags);
+	return true;
+}
+
+static inline bool compact_trylock_irqsave(spinlock_t *lock,
+			unsigned long *flags, struct compact_control *cc)
+{
+	return compact_checklock_irqsave(lock, flags, false, cc);
+}
+
+/*
  * Isolate free pages onto a private freelist. Caller must hold zone->lock.
  * If @strict is true, will abort returning 0 on any invalid PFNs or non-free
  * pages inside of the pageblock (even though it may still end up isolating
@@ -173,7 +214,7 @@ isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn)
 }
 
 /* Update the number of anon and file isolated pages in the zone */
-static void acct_isolated(struct zone *zone, struct compact_control *cc)
+static void acct_isolated(struct zone *zone, bool locked, struct compact_control *cc)
 {
 	struct page *page;
 	unsigned int count[2] = { 0, };
@@ -181,8 +222,14 @@ static void acct_isolated(struct zone *zone, struct compact_control *cc)
 	list_for_each_entry(page, &cc->migratepages, lru)
 		count[!!page_is_file_cache(page)]++;
 
-	__mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
-	__mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
+	/* If locked we can use the interrupt unsafe versions */
+	if (locked) {
+		__mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
+		__mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
+	} else {
+		mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
+		mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
+	}
 }
 
 /* Similar to reclaim, but different enough that they don't share logic */
@@ -228,6 +275,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
 	struct list_head *migratelist = &cc->migratepages;
 	isolate_mode_t mode = 0;
 	struct lruvec *lruvec;
+	unsigned long flags;
+	bool locked;
 
 	/*
 	 * Ensure that there are not too many pages isolated from the LRU
@@ -247,25 +296,22 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
 
 	/* Time to isolate some pages for migration */
 	cond_resched();
-	spin_lock_irq(&zone->lru_lock);
+	spin_lock_irqsave(&zone->lru_lock, flags);
+	locked = true;
 	for (; low_pfn < end_pfn; low_pfn++) {
 		struct page *page;
-		bool locked = true;
 
 		/* give a chance to irqs before checking need_resched() */
 		if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
-			spin_unlock_irq(&zone->lru_lock);
+			spin_unlock_irqrestore(&zone->lru_lock, flags);
 			locked = false;
 		}
-		if (need_resched() || spin_is_contended(&zone->lru_lock)) {
-			if (locked)
-				spin_unlock_irq(&zone->lru_lock);
-			cond_resched();
-			spin_lock_irq(&zone->lru_lock);
-			if (fatal_signal_pending(current))
-				break;
-		} else if (!locked)
-			spin_lock_irq(&zone->lru_lock);
+
+		/* Check if it is ok to still hold the lock */
+		locked = compact_checklock_irqsave(&zone->lru_lock, &flags,
+								locked, cc);
+		if (!locked)
+			break;
 
 		/*
 		 * migrate_pfn does not necessarily start aligned to a
@@ -349,9 +395,10 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
 		}
 	}
 
-	acct_isolated(zone, cc);
+	acct_isolated(zone, locked, cc);
 
-	spin_unlock_irq(&zone->lru_lock);
+	if (locked)
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
 
 	trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
 
@@ -384,6 +431,20 @@ static bool suitable_migration_target(struct page *page)
 }
 
 /*
+ * Returns the start pfn of the last page block in a zone.  This is the starting
+ * point for full compaction of a zone.  Compaction searches for free pages from
+ * the end of each zone, while isolate_freepages_block scans forward inside each
+ * page block.
+ */
+static unsigned long start_free_pfn(struct zone *zone)
+{
+	unsigned long free_pfn;
+	free_pfn = zone->zone_start_pfn + zone->spanned_pages;
+	free_pfn &= ~(pageblock_nr_pages-1);
+	return free_pfn;
+}
+
+/*
  * Based on information in the current compact_control, find blocks
  * suitable for isolating free pages from and then isolate them.
  */
@@ -422,17 +483,6 @@ static void isolate_freepages(struct zone *zone,
 					pfn -= pageblock_nr_pages) {
 		unsigned long isolated;
 
-		/*
-		 * Skip ahead if another thread is compacting in the area
-		 * simultaneously. If we wrapped around, we can only skip
-		 * ahead if zone->compact_cached_free_pfn also wrapped to
-		 * above our starting point.
-		 */
-		if (cc->order > 0 && (!cc->wrapped ||
-				      zone->compact_cached_free_pfn >
-				      cc->start_free_pfn))
-			pfn = min(pfn, zone->compact_cached_free_pfn);
-
 		if (!pfn_valid(pfn))
 			continue;
 
@@ -458,7 +508,16 @@ static void isolate_freepages(struct zone *zone,
 		 * are disabled
 		 */
 		isolated = 0;
-		spin_lock_irqsave(&zone->lock, flags);
+
+		/*
+		 * The zone lock must be held to isolate freepages. This
+		 * unfortunately this is a very coarse lock and can be
+		 * heavily contended if there are parallel allocations
+		 * or parallel compactions. For async compaction do not
+		 * spin on the lock
+		 */
+		if (!compact_trylock_irqsave(&zone->lock, &flags, cc))
+			break;
 		if (suitable_migration_target(page)) {
 			end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn);
 			isolated = isolate_freepages_block(pfn, end_pfn,
@@ -474,7 +533,15 @@ static void isolate_freepages(struct zone *zone,
 		 */
 		if (isolated) {
 			high_pfn = max(high_pfn, pfn);
-			if (cc->order > 0)
+
+			/*
+			 * If the free scanner has wrapped, update
+			 * compact_cached_free_pfn to point to the highest
+			 * pageblock with free pages. This reduces excessive
+			 * scanning of full pageblocks near the end of the
+			 * zone
+			 */
+			if (cc->order > 0 && cc->wrapped)
 				zone->compact_cached_free_pfn = high_pfn;
 		}
 	}
@@ -484,6 +551,11 @@ static void isolate_freepages(struct zone *zone,
 
 	cc->free_pfn = high_pfn;
 	cc->nr_freepages = nr_freepages;
+
+	/* If compact_cached_free_pfn is reset then set it now */
+	if (cc->order > 0 && !cc->wrapped &&
+			zone->compact_cached_free_pfn == start_free_pfn(zone))
+		zone->compact_cached_free_pfn = high_pfn;
 }
 
 /*
@@ -570,20 +642,6 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
 	return ISOLATE_SUCCESS;
 }
 
-/*
- * Returns the start pfn of the last page block in a zone.  This is the starting
- * point for full compaction of a zone.  Compaction searches for free pages from
- * the end of each zone, while isolate_freepages_block scans forward inside each
- * page block.
- */
-static unsigned long start_free_pfn(struct zone *zone)
-{
-	unsigned long free_pfn;
-	free_pfn = zone->zone_start_pfn + zone->spanned_pages;
-	free_pfn &= ~(pageblock_nr_pages-1);
-	return free_pfn;
-}
-
 static int compact_finished(struct zone *zone,
 			    struct compact_control *cc)
 {
@@ -771,7 +829,7 @@ out:
 
 static unsigned long compact_zone_order(struct zone *zone,
 				 int order, gfp_t gfp_mask,
-				 bool sync)
+				 bool sync, bool *contended)
 {
 	struct compact_control cc = {
 		.nr_freepages = 0,
@@ -780,6 +838,7 @@ static unsigned long compact_zone_order(struct zone *zone,
 		.migratetype = allocflags_to_migratetype(gfp_mask),
 		.zone = zone,
 		.sync = sync,
+		.contended = contended,
 	};
 	INIT_LIST_HEAD(&cc.freepages);
 	INIT_LIST_HEAD(&cc.migratepages);
@@ -801,7 +860,7 @@ int sysctl_extfrag_threshold = 500;
  */
 unsigned long try_to_compact_pages(struct zonelist *zonelist,
 			int order, gfp_t gfp_mask, nodemask_t *nodemask,
-			bool sync)
+			bool sync, bool *contended)
 {
 	enum zone_type high_zoneidx = gfp_zone(gfp_mask);
 	int may_enter_fs = gfp_mask & __GFP_FS;
@@ -825,7 +884,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 								nodemask) {
 		int status;
 
-		status = compact_zone_order(zone, order, gfp_mask, sync);
+		status = compact_zone_order(zone, order, gfp_mask, sync,
+						contended);
 		rc = max(status, rc);
 
 		/* If a normal allocation would succeed, stop compacting */
@@ -861,7 +921,7 @@ static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
 		if (cc->order > 0) {
 			int ok = zone_watermark_ok(zone, cc->order,
 						low_wmark_pages(zone), 0, 0);
-			if (ok && cc->order > zone->compact_order_failed)
+			if (ok && cc->order >= zone->compact_order_failed)
 				zone->compact_order_failed = cc->order + 1;
 			/* Currently async compaction is never deferred. */
 			else if (!ok && cc->sync)
diff --git a/mm/filemap.c b/mm/filemap.c
index fa5ca304148e..384344575c37 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1412,12 +1412,8 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 			retval = filemap_write_and_wait_range(mapping, pos,
 					pos + iov_length(iov, nr_segs) - 1);
 			if (!retval) {
-				struct blk_plug plug;
-
-				blk_start_plug(&plug);
 				retval = mapping->a_ops->direct_IO(READ, iocb,
 							iov, pos, nr_segs);
-				blk_finish_plug(&plug);
 			}
 			if (retval > 0) {
 				*ppos = pos + retval;
@@ -2527,14 +2523,12 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
-	struct blk_plug plug;
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
 
 	sb_start_write(inode->i_sb);
 	mutex_lock(&inode->i_mutex);
-	blk_start_plug(&plug);
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
 
@@ -2545,7 +2539,6 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		if (err < 0 && ret > 0)
 			ret = err;
 	}
-	blk_finish_plug(&plug);
 	sb_end_write(inode->i_sb);
 	return ret;
 }
diff --git a/mm/internal.h b/mm/internal.h
index 3314f79d775a..b8c91b342e24 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -130,6 +130,7 @@ struct compact_control {
 	int order;			/* order a direct compactor needs */
 	int migratetype;		/* MOVABLE, RECLAIMABLE etc */
 	struct zone *zone;
+	bool *contended;		/* True if a lock was contended */
 };
 
 unsigned long
diff --git a/mm/mmap.c b/mm/mmap.c
index e3e86914f11a..ae18a48e7e4e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1356,9 +1356,8 @@ out:
 	} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
 		make_pages_present(addr, addr + len);
 
-	if (file && uprobe_mmap(vma))
-		/* matching probes but cannot insert */
-		goto unmap_and_free_vma;
+	if (file)
+		uprobe_mmap(vma);
 
 	return addr;
 
@@ -2309,7 +2308,7 @@ void exit_mmap(struct mm_struct *mm)
 	}
 	vm_unacct_memory(nr_accounted);
 
-	BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
+	WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
 }
 
 /* Insert vm structure into process list sorted by address
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index e5363f34e025..5ad5ce23c1e0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1532,7 +1532,6 @@ int dirty_writeback_centisecs_handler(ctl_table *table, int write,
 	void __user *buffer, size_t *length, loff_t *ppos)
 {
 	proc_dointvec(table, write, buffer, length, ppos);
-	bdi_arm_supers_timer();
 	return 0;
 }
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 009ac285fea7..c66fb875104a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1928,6 +1928,17 @@ this_zone_full:
 		zlc_active = 0;
 		goto zonelist_scan;
 	}
+
+	if (page)
+		/*
+		 * page->pfmemalloc is set when ALLOC_NO_WATERMARKS was
+		 * necessary to allocate the page. The expectation is
+		 * that the caller is taking steps that will free more
+		 * memory. The caller should avoid the page being used
+		 * for !PFMEMALLOC purposes.
+		 */
+		page->pfmemalloc = !!(alloc_flags & ALLOC_NO_WATERMARKS);
+
 	return page;
 }
 
@@ -2091,7 +2102,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 	struct zonelist *zonelist, enum zone_type high_zoneidx,
 	nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
 	int migratetype, bool sync_migration,
-	bool *deferred_compaction,
+	bool *contended_compaction, bool *deferred_compaction,
 	unsigned long *did_some_progress)
 {
 	struct page *page;
@@ -2106,7 +2117,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 
 	current->flags |= PF_MEMALLOC;
 	*did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask,
-						nodemask, sync_migration);
+						nodemask, sync_migration,
+						contended_compaction);
 	current->flags &= ~PF_MEMALLOC;
 	if (*did_some_progress != COMPACT_SKIPPED) {
 
@@ -2152,7 +2164,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 	struct zonelist *zonelist, enum zone_type high_zoneidx,
 	nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
 	int migratetype, bool sync_migration,
-	bool *deferred_compaction,
+	bool *contended_compaction, bool *deferred_compaction,
 	unsigned long *did_some_progress)
 {
 	return NULL;
@@ -2325,6 +2337,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	unsigned long did_some_progress;
 	bool sync_migration = false;
 	bool deferred_compaction = false;
+	bool contended_compaction = false;
 
 	/*
 	 * In the slowpath, we sanity check order to avoid ever trying to
@@ -2389,14 +2402,6 @@ rebalance:
 				zonelist, high_zoneidx, nodemask,
 				preferred_zone, migratetype);
 		if (page) {
-			/*
-			 * page->pfmemalloc is set when ALLOC_NO_WATERMARKS was
-			 * necessary to allocate the page. The expectation is
-			 * that the caller is taking steps that will free more
-			 * memory. The caller should avoid the page being used
-			 * for !PFMEMALLOC purposes.
-			 */
-			page->pfmemalloc = true;
 			goto got_pg;
 		}
 	}
@@ -2422,6 +2427,7 @@ rebalance:
 					nodemask,
 					alloc_flags, preferred_zone,
 					migratetype, sync_migration,
+					&contended_compaction,
 					&deferred_compaction,
 					&did_some_progress);
 	if (page)
@@ -2431,10 +2437,11 @@ rebalance:
 	/*
 	 * If compaction is deferred for high-order allocations, it is because
 	 * sync compaction recently failed. In this is the case and the caller
-	 * has requested the system not be heavily disrupted, fail the
-	 * allocation now instead of entering direct reclaim
+	 * requested a movable allocation that does not heavily disrupt the
+	 * system then fail the allocation instead of entering direct reclaim.
 	 */
-	if (deferred_compaction && (gfp_mask & __GFP_NO_KSWAPD))
+	if ((deferred_compaction || contended_compaction) &&
+						(gfp_mask & __GFP_NO_KSWAPD))
 		goto nopage;
 
 	/* Try direct reclaim and then allocating */
@@ -2505,6 +2512,7 @@ rebalance:
 					nodemask,
 					alloc_flags, preferred_zone,
 					migratetype, sync_migration,
+					&contended_compaction,
 					&deferred_compaction,
 					&did_some_progress);
 		if (page)
@@ -2569,8 +2577,6 @@ retry_cpuset:
 		page = __alloc_pages_slowpath(gfp_mask, order,
 				zonelist, high_zoneidx, nodemask,
 				preferred_zone, migratetype);
-	else
-		page->pfmemalloc = false;
 
 	trace_mm_page_alloc(page, order, gfp_mask, migratetype);
 
diff --git a/mm/slab.c b/mm/slab.c
index f8b0d539b482..811af03a14ef 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3260,6 +3260,7 @@ force_grow:
 
 		/* cache_grow can reenable interrupts, then ac could change. */
 		ac = cpu_cache_get(cachep);
+		node = numa_mem_id();
 
 		/* no objects in sight? abort */
 		if (!x && (ac->avail == 0 || force_refill))