[PATCH 0/7] mmotm - unevictable lru/mlocked pages fixes/cleanup

[PATCH 0/7] mmotm - unevictable lru/mlocked pages fixes/cleanup

[Lee Schermerhorn]

Here are a set of fixes and cleanup to the unevictable lru and
mlocked pages patches against 27-rc1+mmotm-080730-0356.  In
addition to the patches, I have a few suggestions for fixing up
a few patch descriptions, and other potential cleanups, below.

The following patch names are the file names I'm using in my tree.
The names indicate where in the series the patch goes.  I've also
mentioned in the patch descriptions which patch each one fixes.


unevictable-lru-infrastructure-putback-fix1.patch

	I noticed that putback_lru_page() would forget the active
	state of a page in the event of a "redo".  [Note:  I added
	a vm event to record any redos.  I've never seen any redos
	in any of my stress testing since Kamezawa-san reworked
	putback_lru_pages().]  This patch remembers the page's
	incoming PageActive state.  Not sure this is required.

	Can be folded with unevictable-lru-infrastructure.patch

unevictable-lru-infrastructure-putback-fix2.patch

	Remove the unevictable page vm event counting from
	putback_lru_page(), as this breaks a bisect.  The necessary
	vmstat events have not been defined until later in the
	series.  Subsequent patches will add back in the event
	counting at appropriate places

	Can be folded with unevictable-lru-infrastructure.patch

unevictable-lru-page-statistics-add-events.patch

	Define the vmstat events for the unevictable lru
	infrastructure and count them here, separately from
	the mlocked pages stats.

	Renames the NORECL/noreclaim vmstat events to
	UNEVICTABLE/unevictable ...

	This patch may be folded with the
		unevictable-lru-page-statistics.patch

shm_locked-pages-are-unevictable-add-vm-events.patch

	Add unevictable lru event counting to scan of the
	unevictable lru list[s] for a mapping's pages.
	May be folded with shm_locked-pages-are-unevictable.patch

vmstat-mlocked-pages-statistics-add-vm-events.patch

	Add mlocked pages related vm event definitions and counting.
	May be folded with vmstat-mlocked-pages-statistics.patch

mlock-count-attempts-to-free-mlocked-page.patch

	REPLACE the existing patch of this name with this one.
	It resolves patch conflicts resulting from the renaming of
	the events and handles the renaming in unconflicted hunks.

vmstat-unevictable-and-mlocked-pages-vm-events.patch

	REMOVE this patch from the series.  It is superceeded by
	the preceeding patches that define the vm events with the
	appropriate statistics patch.

Other notes and patch description updates:

1) Kosaki-san's munlock rework patch [removal of page table walker]
   has been folded with:
	 mmap-handle-mlocked-pages-during-map-remap-unmap.patch
   Technically, it should be part of:
	 mlock-mlocked-pages-are-unevictable.patch
   where it would have just removed/replaced the patch chunks that
   added the page table walker.

2) Patch description of ramfs-and-ram-disk-pages-are-unevictable.patch
   is stale, since the brd driver replaced rd--ram disk pages are no
   longer on the lru.  I'll send a suggested replacement description as
   part of this series.

3) Since the putback_lru_page() rework, the patch description of
   shm_locked-pages-are-unevictable.patch is stale.  Suggest:

   Remove the text from the last paragraph of the description, starting with:
	"Note that scan_mapping_unevictable_page() must be able to sleep..."

4) Kosaki-san's munlock rework obsolete's note 5 in the description for
   mlock-mlocked-pages-are-unevictable.patch.

   Could just make a note to this effect with the folded "introduce
   __get_user_pages()" patch description.

5) The putback_lru_page() and munlock() rework requires update of the
   unevictable-lru.txt in Documentation.  I'll send an update patch [later].



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[PATCH 1/7] unevictable lru: Remember page's active state

[Lee Schermerhorn]

Fix to unevictable-lru-infrastructure.patch

Not sure this is absolutely required, but:

Preserve page's incoming active flag across retries in
putback_lru_page().


Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

 mm/vmscan.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmscan.c	2008-07-30 12:57:31.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c	2008-07-30 12:58:41.000000000 -0400
@@ -483,12 +483,12 @@ int remove_mapping(struct address_space 
 void putback_lru_page(struct page *page)
 {
 	int lru;
+	int active = !!TestClearPageActive(page);
 	int was_unevictable = PageUnevictable(page);
 
 	VM_BUG_ON(PageLRU(page));
 
 redo:
-	lru = !!TestClearPageActive(page);
 	ClearPageUnevictable(page);
 
 	if (page_evictable(page, NULL)) {
@@ -498,7 +498,7 @@ redo:
 		 * unevictable page on [in]active list.
 		 * We know how to handle that.
 		 */
-		lru += page_is_file_cache(page);
+		lru = active + page_is_file_cache(page);
 		lru_cache_add_lru(page, lru);
 	} else {
 		/*

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[PATCH 2/7] unevictable lru: defer vm event counting

[Lee Schermerhorn]

Fix to unevictable-lru-infrastructure.patch

NORECL_* events are not defined this early in the series.
Remove the event counting from this patch and add in with
unevictable lru statistics [subsequent patch].

Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>

 mm/vmscan.c |    6 ------
 1 file changed, 6 deletions(-)

Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmscan.c	2008-07-30 12:58:41.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c	2008-07-30 12:59:58.000000000 -0400
@@ -484,7 +484,6 @@ void putback_lru_page(struct page *page)
 {
 	int lru;
 	int active = !!TestClearPageActive(page);
-	int was_unevictable = PageUnevictable(page);
 
 	VM_BUG_ON(PageLRU(page));
 
@@ -526,11 +525,6 @@ redo:
 		 */
 	}
 
-	if (was_unevictable && lru != LRU_UNEVICTABLE)
-		count_vm_event(NORECL_PGRESCUED);
-	else if (!was_unevictable && lru == LRU_UNEVICTABLE)
-		count_vm_event(NORECL_PGCULLED);
-
 	put_page(page);		/* drop ref from isolate */
 }
 

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[PATCH 3/7] unevictable lru: add event counting with statistics

[Lee Schermerhorn]

Fix to unevictable-lru-page-statistics.patch

Add unevictable lru infrastructure vm events to the statistics patch.
Rename the "NORECL_" and "noreclaim_" symbols and text strings to
"UNEVICTABLE_" and "unevictable_", respectively.

Currently, both the infrastructure and the mlocked pages event are
added by a single patch later in the series.  This makes it difficult
to add or rework the incremental patches.  The events actually "belong"
with the stats, so pull them up to here.

Also, restore the event counting to putback_lru_page().  This was removed
from previous patch in series where it was "misplaced".  The actual events
weren't defined that early.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

 include/linux/vmstat.h |    5 +++++
 mm/vmscan.c            |    6 ++++++
 mm/vmstat.c            |    5 +++++
 3 files changed, 16 insertions(+)

Index: linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/include/linux/vmstat.h	2008-07-30 12:56:30.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h	2008-07-30 13:17:07.000000000 -0400
@@ -41,6 +41,11 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 #ifdef CONFIG_HUGETLB_PAGE
 		HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
 #endif
+#ifdef CONFIG_UNEVICTABLE_LRU
+		UNEVICTABLE_PGCULLED,	/* culled to noreclaim list */
+		UNEVICTABLE_PGSCANNED,	/* scanned for reclaimability */
+		UNEVICTABLE_PGRESCUED,	/* rescued from noreclaim list */
+#endif
 		NR_VM_EVENT_ITEMS
 };
 
Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmscan.c	2008-07-30 12:59:58.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c	2008-07-30 13:17:21.000000000 -0400
@@ -484,6 +484,7 @@ void putback_lru_page(struct page *page)
 {
 	int lru;
 	int active = !!TestClearPageActive(page);
+	int was_unevictable = PageUnevictable(page);
 
 	VM_BUG_ON(PageLRU(page));
 
@@ -525,6 +526,11 @@ redo:
 		 */
 	}
 
+	if (was_unevictable && lru != LRU_UNEVICTABLE)
+		count_vm_event(UNEVICTABLE_PGRESCUED);
+	else if (!was_unevictable && lru == LRU_UNEVICTABLE)
+		count_vm_event(UNEVICTABLE_PGCULLED);
+
 	put_page(page);		/* drop ref from isolate */
 }
 
Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmstat.c	2008-07-30 13:08:07.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c	2008-07-30 13:16:17.000000000 -0400
@@ -663,6 +663,11 @@ static const char * const vmstat_text[] 
 	"htlb_buddy_alloc_success",
 	"htlb_buddy_alloc_fail",
 #endif
+#ifdef CONFIG_UNEVICTABLE_LRU
+	"unevictable_pgs_culled",
+	"unevictable_pgs_scanned",
+	"unevictable_pgs_rescued",
+#endif
 #endif
 };
 

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[PATCH 4/7] unevictable lru: add event counts to list scan

[Lee Schermerhorn]

Fix to shm_locked-pages-are-unevictable.patch

More breaking up of the single unevictable lru/mlocked pages
vm events patch.

Add the vm events counting to the unevictable lru list
scanning for shm_unlock().

Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>

 mm/vmscan.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmscan.c	2008-07-30 13:26:46.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c	2008-07-30 13:34:58.000000000 -0400
@@ -2407,6 +2407,7 @@ retry:
 		__dec_zone_state(zone, NR_UNEVICTABLE);
 		list_move(&page->lru, &zone->lru[l].list);
 		__inc_zone_state(zone, NR_INACTIVE_ANON + l);
+		__count_vm_event(UNEVICTABLE_PGRESCUED);
 	} else {
 		/*
 		 * rotate unevictable list
@@ -2440,6 +2441,7 @@ void scan_mapping_unevictable_pages(stru
 	while (next < end &&
 		pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
 		int i;
+		int pg_scanned = 0;
 
 		zone = NULL;
 
@@ -2448,6 +2450,7 @@ void scan_mapping_unevictable_pages(stru
 			pgoff_t page_index = page->index;
 			struct zone *pagezone = page_zone(page);
 
+			pg_scanned++;
 			if (page_index > next)
 				next = page_index;
 			next++;
@@ -2465,6 +2468,8 @@ void scan_mapping_unevictable_pages(stru
 		if (zone)
 			spin_unlock_irq(&zone->lru_lock);
 		pagevec_release(&pvec);
+
+		count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
 	}
 
 }

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[PATCH 5/7] mlocked-pages: add event counting with statistics

[Lee Schermerhorn]

Fix to vmstat-mlocked-pages-statistics.patch

Define mlocked pages vm events in the mlocked pages
statistics patch.  Makes for easier incremental patching.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

 include/linux/vmstat.h |    4 ++++
 mm/internal.h          |    4 +++-
 mm/mlock.c             |   33 +++++++++++++++++++++++++--------
 mm/vmstat.c            |    4 ++++
 4 files changed, 36 insertions(+), 9 deletions(-)

Index: linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/include/linux/vmstat.h	2008-07-30 13:26:08.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h	2008-07-30 13:40:43.000000000 -0400
@@ -45,6 +45,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		UNEVICTABLE_PGCULLED,	/* culled to noreclaim list */
 		UNEVICTABLE_PGSCANNED,	/* scanned for reclaimability */
 		UNEVICTABLE_PGRESCUED,	/* rescued from noreclaim list */
+		UNEVICTABLE_PGMLOCKED,
+		UNEVICTABLE_PGMUNLOCKED,
+		UNEVICTABLE_PGCLEARED,	/* on COW, page truncate */
+		UNEVICTABLE_PGSTRANDED,	/* unable to isolate on unlock */
 #endif
 		NR_VM_EVENT_ITEMS
 };
Index: linux-2.6.27-rc1-mmotm-30jul/mm/mlock.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/mlock.c	2008-07-30 13:36:17.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/mlock.c	2008-07-30 13:47:04.000000000 -0400
@@ -61,6 +61,7 @@ void __clear_page_mlock(struct page *pag
 	}
 
 	dec_zone_page_state(page, NR_MLOCK);
+	count_vm_event(UNEVICTABLE_PGCLEARED);
 	if (!isolate_lru_page(page)) {
 		putback_lru_page(page);
 	} else {
@@ -70,6 +71,9 @@ void __clear_page_mlock(struct page *pag
 		lru_add_drain_all();
 		if (!isolate_lru_page(page))
 			putback_lru_page(page);
+		else if (PageUnevictable(page))
+			count_vm_event(UNEVICTABLE_PGSTRANDED);
+
 	}
 }
 
@@ -83,6 +87,7 @@ void mlock_vma_page(struct page *page)
 
 	if (!TestSetPageMlocked(page)) {
 		inc_zone_page_state(page, NR_MLOCK);
+		count_vm_event(UNEVICTABLE_PGMLOCKED);
 		if (!isolate_lru_page(page))
 			putback_lru_page(page);
 	}
@@ -113,16 +118,28 @@ static void munlock_vma_page(struct page
 	if (TestClearPageMlocked(page)) {
 		dec_zone_page_state(page, NR_MLOCK);
 		if (!isolate_lru_page(page)) {
-			try_to_munlock(page);	/* maybe relock the page */
+			int ret = try_to_munlock(page);
+			/*
+			 * did try_to_unlock() succeed or punt?
+			 */
+			if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN)
+				count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
 			putback_lru_page(page);
+		} else {
+			/*
+			 * We lost the race.  let try_to_unmap() deal
+			 * with it.  At least we get the page state and
+			 * mlock stats right.  However, page is still on
+			 * the noreclaim list.  We'll fix that up when
+			 * the page is eventually freed or we scan the
+			 * noreclaim list.
+			 */
+			if (PageUnevictable(page))
+				count_vm_event(UNEVICTABLE_PGSTRANDED);
+			else
+				count_vm_event(UNEVICTABLE_PGMUNLOCKED);
 		}
-		/*
-		 * Else we lost the race.  let try_to_unmap() deal with it.
-		 * At least we get the page state and mlock stats right.
-		 * However, page is still on the noreclaim list.  We'll fix
-		 * that up when the page is eventually freed or we scan the
-		 * noreclaim list.
-		 */
 	}
 }
 
Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmstat.c	2008-07-30 13:36:17.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c	2008-07-30 13:48:12.000000000 -0400
@@ -668,6 +668,10 @@ static const char * const vmstat_text[] 
 	"unevictable_pgs_culled",
 	"unevictable_pgs_scanned",
 	"unevictable_pgs_rescued",
+	"unevictable_pgs_mlocked",
+	"unevictable_pgs_munlocked",
+	"unevictable_pgs_cleared",
+	"unevictable_pgs_stranded",
 #endif
 #endif
 };
Index: linux-2.6.27-rc1-mmotm-30jul/mm/internal.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/internal.h	2008-07-30 13:36:17.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/internal.h	2008-07-30 13:46:31.000000000 -0400
@@ -101,8 +101,10 @@ static inline int is_mlocked_vma(struct 
 	if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
 		return 0;
 
-	if (!TestSetPageMlocked(page))
+	if (!TestSetPageMlocked(page)) {
 		inc_zone_page_state(page, NR_MLOCK);
+		count_vm_event(UNEVICTABLE_PGMLOCKED);
+	}
 	return 1;
 }
 

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[PATCH 6/7] mlocked-pages: patch reject resolution and event renames

[Lee Schermerhorn, Lee Schermerhorn]

Against:  [27-rc1+]mmotm-080730-0356

Replaces:  mlock-count-attempts-to-free-mlocked-page.patch in
the mmotm series.

Reworked to resolve patch conflicts introduced by other patches,
including rename of unevictable lru/mlocked pages events.

Allow free of mlock()ed pages.  This shouldn't happen, but during
developement, it occasionally did.

This patch allows us to survive that condition, while keeping the
statistics and events correct for debug.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

 include/linux/vmstat.h |    1 +
 mm/internal.h          |   17 +++++++++++++++++
 mm/page_alloc.c        |    1 +
 mm/vmstat.c            |    1 +
 4 files changed, 20 insertions(+)

Index: linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/include/linux/vmstat.h	2008-07-30 13:40:43.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h	2008-07-30 13:51:24.000000000 -0400
@@ -49,6 +49,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		UNEVICTABLE_PGMUNLOCKED,
 		UNEVICTABLE_PGCLEARED,	/* on COW, page truncate */
 		UNEVICTABLE_PGSTRANDED,	/* unable to isolate on unlock */
+		UNEVICTABLE_MLOCKFREED,
 #endif
 		NR_VM_EVENT_ITEMS
 };
Index: linux-2.6.27-rc1-mmotm-30jul/mm/internal.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/internal.h	2008-07-30 13:46:31.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/internal.h	2008-07-30 13:52:28.000000000 -0400
@@ -146,6 +146,22 @@ static inline void mlock_migrate_page(st
 	}
 }
 
+/*
+ * free_page_mlock() -- clean up attempts to free and mlocked() page.
+ * Page should not be on lru, so no need to fix that up.
+ * free_pages_check() will verify...
+ */
+static inline void free_page_mlock(struct page *page)
+{
+	if (unlikely(TestClearPageMlocked(page))) {
+		unsigned long flags;
+
+		local_irq_save(flags);
+		__dec_zone_page_state(page, NR_MLOCK);
+		__count_vm_event(UNEVICTABLE_MLOCKFREED);
+		local_irq_restore(flags);
+	}
+}
 
 #else /* CONFIG_UNEVICTABLE_LRU */
 static inline int is_mlocked_vma(struct vm_area_struct *v, struct page *p)
@@ -155,6 +171,7 @@ static inline int is_mlocked_vma(struct 
 static inline void clear_page_mlock(struct page *page) { }
 static inline void mlock_vma_page(struct page *page) { }
 static inline void mlock_migrate_page(struct page *new, struct page *old) { }
+static inline void free_page_mlock(struct page *page) { }
 
 #endif /* CONFIG_UNEVICTABLE_LRU */
 
Index: linux-2.6.27-rc1-mmotm-30jul/mm/page_alloc.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/page_alloc.c	2008-07-30 13:35:55.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/page_alloc.c	2008-07-30 13:50:04.000000000 -0400
@@ -451,6 +451,7 @@ static inline void __free_one_page(struc
 
 static inline int free_pages_check(struct page *page)
 {
+	free_page_mlock(page);
 	if (unlikely(page_mapcount(page) |
 		(page->mapping != NULL)  |
 		(page_get_page_cgroup(page) != NULL) |
Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmstat.c	2008-07-30 13:48:12.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c	2008-07-30 13:52:03.000000000 -0400
@@ -672,6 +672,7 @@ static const char * const vmstat_text[] 
 	"unevictable_pgs_munlocked",
 	"unevictable_pgs_cleared",
 	"unevictable_pgs_stranded",
+	"unevictable_pgs_mlockfreed",
 #endif
 #endif
 };

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[PATCH/DESCRIPTION 7/7] unevictable lru: replace patch description

[Lee Schermerhorn]

Not really a patch, per se:

Suggested patch description replacement for:
	ramfs-and-ram-disk-pages-are-unevictable.patch
in 27-rc1-mmotm-080730...

---

Christoph Lameter pointed out that ram disk pages also clutter the LRU
lists.  When vmscan finds them dirty and tries to clean them, the ram disk
writeback function just redirties the page so that it goes back onto the
active list.  Round and round she goes...

With the ram disk driver [rd.c] replaced by the newer 'brd.c', this is
no longer the case, as ram disk pages are no longer maintained on the
lru.  [This makes them unmigratable for defrag or memory hot remove,
but that can be addressed by a separate patch series.]  However, the
ramfs pages behave like ram disk pages used to, so:

Define new address_space flag [shares address_space flags member with
mapping's gfp mask] to indicate that the address space contains all
unevictable pages.  This will provide for efficient testing of ramfs
pages in page_evictable().

Also provide wrapper functions to set/test the unevictable state to
minimize #ifdefs in ramfs driver and any other users of this facility.

Set the unevictable state on address_space structures for new ramfs
inodes.  Test the unevictable state in page_evictable() to cull
unevictable pages.

These changes depend on [CONFIG_]UNEVICTABLE_LRU.

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Re: [PATCH 6/7] mlocked-pages: patch reject resolution and event renames

[Andrew Morton]

On Wed, 30 Jul 2008 16:06:55 -0400
Lee Schermerhorn <lee.schermerhorn@hp.com> wrote:

> Reworked to resolve patch conflicts introduced by other patches,
> including rename of unevictable lru/mlocked pages events.

I hope I was supposed to drop
vmstat-unevictable-and-mlocked-pages-vm-events.patch - it was getting
100% rejects.  After dropping it, everything applied.  Dunno if it
compiles yet.

I have a feeling that I merged all these patches too soon - the amount
of rework has been tremendous.  Are we done yet?

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Re: [PATCH 1/7] unevictable lru: Remember page's active state

[KOSAKI Motohiro]

> @@ -483,12 +483,12 @@ int remove_mapping(struct address_space
>  void putback_lru_page(struct page *page)
>  {
>        int lru;
> +       int active = !!TestClearPageActive(page);
>        int was_unevictable = PageUnevictable(page);
>
>        VM_BUG_ON(PageLRU(page));
>
>  redo:
> -       lru = !!TestClearPageActive(page);
>        ClearPageUnevictable(page);
>
>        if (page_evictable(page, NULL)) {
> @@ -498,7 +498,7 @@ redo:
>                 * unevictable page on [in]active list.
>                 * We know how to handle that.
>                 */
> -               lru += page_is_file_cache(page);
> +               lru = active + page_is_file_cache(page);
>                lru_cache_add_lru(page, lru);
>        } else {

Indeed.

          Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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Re: [PATCH 2/7] unevictable lru: defer vm event counting

[KOSAKI Motohiro]

2008/7/31 Lee Schermerhorn <lee.schermerhorn@hp.com>:
> Fix to unevictable-lru-infrastructure.patch
>
> NORECL_* events are not defined this early in the series.
> Remove the event counting from this patch and add in with
> unevictable lru statistics [subsequent patch].
>
> Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>

Oops, sorry my bad.

   Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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Re: [PATCH 3/7] unevictable lru: add event counting with statistics

[KOSAKI Motohiro]

> Fix to unevictable-lru-page-statistics.patch
>
> Add unevictable lru infrastructure vm events to the statistics patch.
> Rename the "NORECL_" and "noreclaim_" symbols and text strings to
> "UNEVICTABLE_" and "unevictable_", respectively.
>
> Currently, both the infrastructure and the mlocked pages event are
> added by a single patch later in the series.  This makes it difficult
> to add or rework the incremental patches.  The events actually "belong"
> with the stats, so pull them up to here.
>
> Also, restore the event counting to putback_lru_page().  This was removed
> from previous patch in series where it was "misplaced".  The actual events
> weren't defined that early.

okey.
   Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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Re: [PATCH 4/7] unevictable lru: add event counts to list scan

[KOSAKI Motohiro]

>  mm/vmscan.c |    5 +++++
>  1 file changed, 5 insertions(+)
>
> Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c
> ===================================================================
> --- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmscan.c       2008-07-30 13:26:46.000000000 -0400
> +++ linux-2.6.27-rc1-mmotm-30jul/mm/vmscan.c    2008-07-30 13:34:58.000000000 -0400
> @@ -2407,6 +2407,7 @@ retry:
>                __dec_zone_state(zone, NR_UNEVICTABLE);
>                list_move(&page->lru, &zone->lru[l].list);
>                __inc_zone_state(zone, NR_INACTIVE_ANON + l);
> +               __count_vm_event(UNEVICTABLE_PGRESCUED);
>        } else {
>                /*
>                 * rotate unevictable list
> @@ -2440,6 +2441,7 @@ void scan_mapping_unevictable_pages(stru
>        while (next < end &&
>                pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
>                int i;
> +               int pg_scanned = 0;
>
>                zone = NULL;
>
> @@ -2448,6 +2450,7 @@ void scan_mapping_unevictable_pages(stru
>                        pgoff_t page_index = page->index;
>                        struct zone *pagezone = page_zone(page);
>
> +                       pg_scanned++;
>                        if (page_index > next)
>                                next = page_index;
>                        next++;
> @@ -2465,6 +2468,8 @@ void scan_mapping_unevictable_pages(stru
>                if (zone)
>                        spin_unlock_irq(&zone->lru_lock);
>                pagevec_release(&pvec);
> +
> +               count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);

yup, ok.

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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Re: [PATCH 5/7] mlocked-pages: add event counting with statistics

[KOSAKI Motohiro]

> +               } else {
> +                       /*
> +                        * We lost the race.  let try_to_unmap() deal
> +                        * with it.  At least we get the page state and
> +                        * mlock stats right.  However, page is still on
> +                        * the noreclaim list.  We'll fix that up when
> +                        * the page is eventually freed or we scan the
> +                        * noreclaim list.

                               unevictable list?

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Re: [PATCH/DESCRIPTION 7/7] unevictable lru: replace patch description

[KOSAKI Motohiro]

> Christoph Lameter pointed out that ram disk pages also clutter the LRU
> lists.  When vmscan finds them dirty and tries to clean them, the ram disk
> writeback function just redirties the page so that it goes back onto the
> active list.  Round and round she goes...
>
> With the ram disk driver [rd.c] replaced by the newer 'brd.c', this is
> no longer the case, as ram disk pages are no longer maintained on the
> lru.  [This makes them unmigratable for defrag or memory hot remove,
> but that can be addressed by a separate patch series.]  However, the
> ramfs pages behave like ram disk pages used to, so:
>
> Define new address_space flag [shares address_space flags member with
> mapping's gfp mask] to indicate that the address space contains all
> unevictable pages.  This will provide for efficient testing of ramfs
> pages in page_evictable().
>
> Also provide wrapper functions to set/test the unevictable state to
> minimize #ifdefs in ramfs driver and any other users of this facility.
>
> Set the unevictable state on address_space structures for new ramfs
> inodes.  Test the unevictable state in page_evictable() to cull
> unevictable pages.
>
> These changes depend on [CONFIG_]UNEVICTABLE_LRU.

looks good to me.
but I can't believe my english skill.....

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Re: [PATCH 5/7] mlocked-pages: add event counting with statistics

[Lee Schermerhorn]

On Thu, 2008-07-31 at 05:40 +0900, KOSAKI Motohiro wrote:
> > +               } else {
> > +                       /*
> > +                        * We lost the race.  let try_to_unmap() deal
> > +                        * with it.  At least we get the page state and
> > +                        * mlock stats right.  However, page is still on
> > +                        * the noreclaim list.  We'll fix that up when
> > +                        * the page is eventually freed or we scan the
> > +                        * noreclaim list.
> 
>                                unevictable list?

Yeah.  I missed that one.  Time for a global search, I guess.

Thanks,
Lee

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Re: [PATCH 6/7] mlocked-pages: patch reject resolution and event renames

[Lee Schermerhorn]

On Wed, 2008-07-30 at 13:30 -0700, Andrew Morton wrote:
> On Wed, 30 Jul 2008 16:06:55 -0400
> Lee Schermerhorn <lee.schermerhorn@hp.com> wrote:
> 
> > Reworked to resolve patch conflicts introduced by other patches,
> > including rename of unevictable lru/mlocked pages events.
> 
> I hope I was supposed to drop
> vmstat-unevictable-and-mlocked-pages-vm-events.patch - it was getting
> 100% rejects.  After dropping it, everything applied.  Dunno if it
> compiles yet.

Yeah.  I did state that explicitly in the cover message.  In upper case,
even!  I had applied all of these patches in my copy of the mmotm tree
and it does compile.  Of course, you've probably added a few patches
that I don't have in the meantime.

> 
> I have a feeling that I merged all these patches too soon - the amount
> of rework has been tremendous.  Are we done yet?

By merging them, we did find problems on platforms and configurations
that I can't easily test.  Most of the rework has served to simplify the
resulting code, IMO.

As for being done, I don't know.  Depends on whether anyone else finds
issues with other configs or platforms that haven't tested these series
yet.  And, I'm continuing to review the current patches.

I did run the mmotm-080729 series for over 20 hours last night under a
fairly heavy stress load on one of my ia64 systems.  No errors, no
leaked pages, ...  Looks pretty good.  Until the next test comes
along...

So, as I mentioned, I've rebuilt with today's fixes applied to
mmotm-080730 and will test more tomorrow.  [We just moved our lab across
state lines and my test systems are just coming on-line.]  I'll keep an
eye on the mmotm site and try to stay current with that.

Thanks for applying these.
Lee



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Re: [PATCH 6/7] mlocked-pages: patch reject resolution and event renames

[Rik van Riel]

On Wed, 30 Jul 2008 13:30:04 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> I have a feeling that I merged all these patches too soon - the amount
> of rework has been tremendous.  Are we done yet?

I can't speak for the unreclaimable part of the patch series,
but the first half of the split LRU series should be in a good
shape now that you merged the patch from Johannes Weiner.

I am not aware of a situation where the split LRU VM performs
worse than what is currently upstream, but I will continue to
try finding performance regressions to fix :)

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