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Subject[patch 12/21] No Reclaim LRU Infrastructure
V1 -> V3:
+ rebase to 23-mm1 atop RvR's split LRU series
+ define NR_NORECLAIM and LRU_NORECLAIM to avoid errors when not
configured.

V1 -> V2:
+ handle review comments -- various typos and errors.
+ extract "putback_all_noreclaim_pages()" into a separate patch
and rework as "scan_all_zones_noreclaim_pages().

Infrastructure to manage pages excluded from reclaim--i.e., hidden
from vmscan. Based on a patch by Larry Woodman of Red Hat. Reworked
to maintain "nonreclaimable" pages on a separate per-zone LRU list,
to "hide" them from vmscan. A separate noreclaim pagevec is provided
for shrink_active_list() to move nonreclaimable pages to the noreclaim
list without over burdening the zone lru_lock.

Pages on the noreclaim list have both PG_noreclaim and PG_lru set.
Thus, PG_noreclaim is analogous to and mutually exclusive with
PG_active--it specifies which LRU list the page is on.

The noreclaim infrastructure is enabled by a new mm Kconfig option
[CONFIG_]NORECLAIM.

A new function 'page_reclaimable(page, vma)' in vmscan.c tests whether
or not a page is reclaimable. Subsequent patches will add the various
!reclaimable tests. We'll want to keep these tests light-weight for
use in shrink_active_list() and, possibly, the fault path.

Notes:

1. for now, use bit 30 in page flags. This restricts the no reclaim
infrastructure to 64-bit systems. [The mlock patch, later in this
series, uses another of these 64-bit-system-only flags.]

Rationale: 32-bit systems have no free page flags and are less
likely to have the large amounts of memory that exhibit the problems
this series attempts to solve. [I'm sure someone will disabuse me
of this notion.]

Thus, NORECLAIM currently depends on [CONFIG_]64BIT.

2. The pagevec to move pages to the noreclaim list results in another
loop at the end of shrink_active_list(). If we ultimately adopt Rik
van Riel's split lru approach, I think we'll need to find a way to
factor all of these loops into some common code.

3. TODO: Memory Controllers maintain separate active and inactive lists.
Need to consider whether they should also maintain a noreclaim list.
Also, convert to use Christoph's array of indexed lru variables?

See //TODO note in mm/memcontrol.c re: isolating non-reclaimable
pages.
4. TODO: more factoring of lru list handling. But, I want to get this
as close to functionally correct as possible before introducing those
perturbations.

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

Index: linux-2.6.25-rc2-mm1/mm/Kconfig
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/Kconfig 2008-02-19 16:23:09.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/Kconfig 2008-02-28 11:05:04.000000000 -0500
@@ -193,3 +193,13 @@ config NR_QUICK
config VIRT_TO_BUS
def_bool y
depends on !ARCH_NO_VIRT_TO_BUS
+
+config NORECLAIM
+ bool "Track non-reclaimable pages (EXPERIMENTAL; 64BIT only)"
+ depends on EXPERIMENTAL && 64BIT
+ help
+ Supports tracking of non-reclaimable pages off the [in]active lists
+ to avoid excessive reclaim overhead on large memory systems. Pages
+ may be non-reclaimable because: they are locked into memory, they
+ are anonymous pages for which no swap space exists, or they are anon
+ pages that are expensive to unmap [long anon_vma "related vma" list.]
Index: linux-2.6.25-rc2-mm1/include/linux/page-flags.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/include/linux/page-flags.h 2008-02-28 00:26:04.000000000 -0500
+++ linux-2.6.25-rc2-mm1/include/linux/page-flags.h 2008-02-28 12:18:48.000000000 -0500
@@ -107,6 +107,8 @@
* 63 32 0
*/
#define PG_uncached 31 /* Page has been mapped as uncached */
+
+#define PG_noreclaim 30 /* Page is "non-reclaimable" */
#endif

/*
@@ -196,6 +198,7 @@ static inline void SetPageUptodate(struc
#define SetPageActive(page) set_bit(PG_active, &(page)->flags)
#define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
#define __ClearPageActive(page) __clear_bit(PG_active, &(page)->flags)
+#define TestClearPageActive(page) test_and_clear_bit(PG_active, &(page)->flags)

#define PageSlab(page) test_bit(PG_slab, &(page)->flags)
#define __SetPageSlab(page) __set_bit(PG_slab, &(page)->flags)
@@ -297,6 +300,21 @@ static inline void __ClearPageTail(struc
#define PageSwapCache(page) 0
#endif

+#ifdef CONFIG_NORECLAIM
+#define PageNoreclaim(page) test_bit(PG_noreclaim, &(page)->flags)
+#define SetPageNoreclaim(page) set_bit(PG_noreclaim, &(page)->flags)
+#define ClearPageNoreclaim(page) clear_bit(PG_noreclaim, &(page)->flags)
+#define __ClearPageNoreclaim(page) __clear_bit(PG_noreclaim, &(page)->flags)
+#define TestClearPageNoreclaim(page) test_and_clear_bit(PG_noreclaim, \
+ &(page)->flags)
+#else
+#define PageNoreclaim(page) 0
+#define SetPageNoreclaim(page)
+#define ClearPageNoreclaim(page)
+#define __ClearPageNoreclaim(page)
+#define TestClearPageNoreclaim(page) 0
+#endif
+
#define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
#define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
Index: linux-2.6.25-rc2-mm1/include/linux/mmzone.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/include/linux/mmzone.h 2008-02-28 00:29:40.000000000 -0500
+++ linux-2.6.25-rc2-mm1/include/linux/mmzone.h 2008-02-28 11:45:14.000000000 -0500
@@ -84,6 +84,11 @@ enum zone_stat_item {
NR_ACTIVE_ANON, /* " " " " " */
NR_INACTIVE_FILE, /* " " " " " */
NR_ACTIVE_FILE, /* " " " " " */
+#ifdef CONFIG_NORECLAIM
+ NR_NORECLAIM, /* " " " " " */
+#else
+ NR_NORECLAIM=NR_ACTIVE_FILE, /* avoid compiler errors in dead code */
+#endif
NR_ANON_PAGES, /* Mapped anonymous pages */
NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
only modified from process context */
@@ -122,10 +127,18 @@ enum lru_list {
LRU_ACTIVE_ANON = LRU_BASE + LRU_ACTIVE,
LRU_INACTIVE_FILE = LRU_BASE + LRU_FILE,
LRU_ACTIVE_FILE = LRU_BASE + LRU_FILE + LRU_ACTIVE,
- NR_LRU_LISTS };
+#ifdef CONFIG_NORECLAIM
+ LRU_NORECLAIM,
+#else
+ LRU_NORECLAIM=LRU_ACTIVE_FILE, /* avoid compiler errors in dead code */
+#endif
+ NR_LRU_LISTS
+};

#define for_each_lru(l) for (l = 0; l < NR_LRU_LISTS; l++)

+#define for_each_reclaimable_lru(l) for (l = 0; l <= LRU_ACTIVE_FILE; l++)
+
static inline int is_file_lru(enum lru_list l)
{
if (l == LRU_INACTIVE_FILE || l == LRU_ACTIVE_FILE)
@@ -140,6 +153,15 @@ static inline int is_active_lru(enum lru
return 0;
}

+static inline int is_noreclaim_lru(enum lru_list l)
+{
+#ifdef CONFIG_NORECLAIM
+ if (l == LRU_NORECLAIM)
+ return 1;
+#endif
+ return 0;
+}
+
enum lru_list page_lru(struct page *page);

struct per_cpu_pages {
Index: linux-2.6.25-rc2-mm1/mm/page_alloc.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/page_alloc.c 2008-02-28 00:29:40.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/page_alloc.c 2008-02-28 11:05:04.000000000 -0500
@@ -248,6 +248,9 @@ static void bad_page(struct page *page)
1 << PG_private |
1 << PG_locked |
1 << PG_active |
+#ifdef CONFIG_NORECLAIM
+ 1 << PG_noreclaim |
+#endif
1 << PG_dirty |
1 << PG_reclaim |
1 << PG_slab |
@@ -482,6 +485,9 @@ static inline int free_pages_check(struc
1 << PG_swapcache |
1 << PG_writeback |
1 << PG_reserved |
+#ifdef CONFIG_NORECLAIM
+ 1 << PG_noreclaim |
+#endif
1 << PG_buddy ))))
bad_page(page);
if (PageDirty(page))
@@ -629,6 +635,9 @@ static int prep_new_page(struct page *pa
1 << PG_private |
1 << PG_locked |
1 << PG_active |
+#ifdef CONFIG_NORECLAIM
+ 1 << PG_noreclaim |
+#endif
1 << PG_dirty |
1 << PG_slab |
1 << PG_swapcache |
Index: linux-2.6.25-rc2-mm1/include/linux/mm_inline.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/include/linux/mm_inline.h 2008-02-28 00:29:35.000000000 -0500
+++ linux-2.6.25-rc2-mm1/include/linux/mm_inline.h 2008-02-28 12:20:07.000000000 -0500
@@ -81,17 +81,42 @@ del_page_from_active_file_list(struct zo
del_page_from_lru_list(zone, page, LRU_INACTIVE_FILE);
}

+#ifdef CONFIG_NORECLAIM
+static inline void
+add_page_to_noreclaim_list(struct zone *zone, struct page *page)
+{
+ add_page_to_lru_list(zone, page, LRU_NORECLAIM);
+}
+
+static inline void
+del_page_from_noreclaim_list(struct zone *zone, struct page *page)
+{
+ del_page_from_lru_list(zone, page, LRU_NORECLAIM);
+}
+#else
+static inline void
+add_page_to_noreclaim_list(struct zone *zone, struct page *page) { }
+
+static inline void
+del_page_from_noreclaim_list(struct zone *zone, struct page *page) { }
+#endif
+
static inline void
del_page_from_lru(struct zone *zone, struct page *page)
{
enum lru_list l = LRU_INACTIVE_ANON;

list_del(&page->lru);
- if (PageActive(page)) {
- __ClearPageActive(page);
- l += LRU_ACTIVE;
+ if (PageNoreclaim(page)) {
+ __ClearPageNoreclaim(page);
+ l = LRU_NORECLAIM;
+ } else {
+ if (PageActive(page)) {
+ __ClearPageActive(page);
+ l += LRU_ACTIVE;
+ }
+ l += page_file_cache(page);
}
- l += page_file_cache(page);
__dec_zone_state(zone, NR_INACTIVE_ANON + l);
}

Index: linux-2.6.25-rc2-mm1/include/linux/swap.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/include/linux/swap.h 2008-02-28 00:27:06.000000000 -0500
+++ linux-2.6.25-rc2-mm1/include/linux/swap.h 2008-02-28 12:05:42.000000000 -0500
@@ -173,6 +173,8 @@ extern unsigned int nr_free_pagecache_pa
/* linux/mm/swap.c */
extern void __lru_cache_add(struct page *, enum lru_list lru);
extern void lru_cache_add_lru(struct page *, enum lru_list lru);
+extern void lru_cache_add_active_or_noreclaim(struct page *,
+ struct vm_area_struct *);
extern void activate_page(struct page *);
extern void mark_page_accessed(struct page *);
extern void lru_add_drain(void);
@@ -204,6 +206,18 @@ static inline void lru_cache_add_active_
__lru_cache_add(page, LRU_ACTIVE_FILE);
}

+#ifdef CONFIG_NORECLAIM
+static inline void lru_cache_add_noreclaim(struct page *page)
+{
+ __lru_cache_add(page, LRU_NORECLAIM);
+}
+#else
+static inline void lru_cache_add_noreclaim(struct page *page)
+{
+ BUG("Noreclaim not configured, but page added anyway?!");
+}
+#endif
+
/* linux/mm/vmscan.c */
extern unsigned long try_to_free_pages(struct zone **zones, int order,
gfp_t gfp_mask);
@@ -228,6 +242,16 @@ static inline int zone_reclaim(struct zo
}
#endif

+#ifdef CONFIG_NORECLAIM
+extern int page_reclaimable(struct page *page, struct vm_area_struct *vma);
+#else
+static inline int page_reclaimable(struct page *page,
+ struct vm_area_struct *vma)
+{
+ return 1;
+}
+#endif
+
extern int kswapd_run(int nid);

#ifdef CONFIG_MMU
Index: linux-2.6.25-rc2-mm1/include/linux/pagevec.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/include/linux/pagevec.h 2008-02-28 00:27:06.000000000 -0500
+++ linux-2.6.25-rc2-mm1/include/linux/pagevec.h 2008-02-28 11:54:34.000000000 -0500
@@ -101,6 +101,12 @@ static inline void __pagevec_lru_add_act
____pagevec_lru_add(pvec, LRU_ACTIVE_FILE);
}

+#ifdef CONFIG_NORECLAIM
+static inline void __pagevec_lru_add_noreclaim(struct pagevec *pvec)
+{
+ ____pagevec_lru_add(pvec, LRU_NORECLAIM);
+}
+#endif

static inline void pagevec_lru_add_file(struct pagevec *pvec)
{
Index: linux-2.6.25-rc2-mm1/mm/swap.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/swap.c 2008-02-28 00:29:40.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/swap.c 2008-02-28 12:21:42.000000000 -0500
@@ -103,9 +103,13 @@ enum lru_list page_lru(struct page *page
{
enum lru_list lru = LRU_BASE;

- if (PageActive(page))
- lru += LRU_ACTIVE;
- lru += page_file_cache(page);
+ if (PageNoreclaim(page))
+ lru = LRU_NORECLAIM;
+ else {
+ if (PageActive(page))
+ lru += LRU_ACTIVE;
+ lru += page_file_cache(page);
+ }

return lru;
}
@@ -130,7 +134,8 @@ static void pagevec_move_tail(struct pag
zone = pagezone;
spin_lock(&zone->lru_lock);
}
- if (PageLRU(page) && !PageActive(page)) {
+ if (PageLRU(page) && !PageActive(page) &&
+ !PageNoreclaim(page)) {
if (page_file_cache(page)) {
list_move_tail(&page->lru,
&zone->list[LRU_INACTIVE_FILE]);
@@ -164,7 +169,7 @@ int rotate_reclaimable_page(struct page
return 1;
if (PageDirty(page))
return 1;
- if (PageActive(page))
+ if (PageActive(page) || PageNoreclaim(page))
return 1;
if (!PageLRU(page))
return 1;
@@ -190,7 +195,7 @@ void activate_page(struct page *page)
struct zone *zone = page_zone(page);

spin_lock_irq(&zone->lru_lock);
- if (PageLRU(page) && !PageActive(page)) {
+ if (PageLRU(page) && !PageActive(page) && !PageNoreclaim(page)) {
int file = page_file_cache(page);
int lru = LRU_BASE + file;
del_page_from_lru_list(zone, page, lru);
@@ -222,7 +227,8 @@ void activate_page(struct page *page)
*/
void mark_page_accessed(struct page *page)
{
- if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
+ if (!PageActive(page) && !PageNoreclaim(page) &&
+ PageReferenced(page) && PageLRU(page)) {
activate_page(page);
ClearPageReferenced(page);
} else if (!PageReferenced(page)) {
@@ -245,13 +251,29 @@ void __lru_cache_add(struct page *page,
void lru_cache_add_lru(struct page *page, enum lru_list lru)
{
if (PageActive(page)) {
+ VM_BUG_ON(PageNoreclaim(page));
ClearPageActive(page);
+ } else if (PageNoreclaim(page)) {
+ VM_BUG_ON(PageActive(page));
+ ClearPageNoreclaim(page);
}

- VM_BUG_ON(PageLRU(page) || PageActive(page));
+ VM_BUG_ON(PageLRU(page) || PageActive(page) || PageNoreclaim(page));
__lru_cache_add(page, lru);
}

+void lru_cache_add_active_or_noreclaim(struct page *page,
+ struct vm_area_struct *vma)
+{
+ if (page_reclaimable(page, vma)) {
+ if (page_file_cache(page))
+ lru_cache_add_active_file(page);
+ else
+ lru_cache_add_active_anon(page);
+ } else
+ lru_cache_add_noreclaim(page);
+}
+
/*
* Drain pages out of the cpu's pagevecs.
* Either "cpu" is the current CPU, and preemption has already been
@@ -349,6 +371,8 @@ void release_pages(struct page **pages,

if (PageLRU(page)) {
struct zone *pagezone = page_zone(page);
+ int is_lru_page;
+
if (pagezone != zone) {
if (zone)
spin_unlock_irqrestore(&zone->lru_lock,
@@ -356,8 +380,10 @@ void release_pages(struct page **pages,
zone = pagezone;
spin_lock_irqsave(&zone->lru_lock, flags);
}
- VM_BUG_ON(!PageLRU(page));
- __ClearPageLRU(page);
+ is_lru_page = PageLRU(page);
+ VM_BUG_ON(!(is_lru_page));
+ if (is_lru_page)
+ __ClearPageLRU(page);
del_page_from_lru(zone, page);
}

@@ -436,10 +462,13 @@ void ____pagevec_lru_add(struct pagevec
zone = pagezone;
spin_lock_irq(&zone->lru_lock);
}
+ VM_BUG_ON(PageActive(page) || PageNoreclaim(page));
VM_BUG_ON(PageLRU(page));
SetPageLRU(page);
if (is_active_lru(lru))
SetPageActive(page);
+ else if (is_noreclaim_lru(lru))
+ SetPageNoreclaim(page);
add_page_to_lru_list(zone, page, lru);
}
if (zone)
Index: linux-2.6.25-rc2-mm1/mm/migrate.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/migrate.c 2008-02-28 00:26:04.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/migrate.c 2008-02-28 11:05:04.000000000 -0500
@@ -326,8 +326,11 @@ static void migrate_page_copy(struct pag
SetPageReferenced(newpage);
if (PageUptodate(page))
SetPageUptodate(newpage);
- if (PageActive(page))
+ if (TestClearPageActive(page)) {
+ VM_BUG_ON(PageNoreclaim(page));
SetPageActive(newpage);
+ } else if (TestClearPageNoreclaim(page))
+ SetPageNoreclaim(newpage);
if (PageChecked(page))
SetPageChecked(newpage);
if (PageMappedToDisk(page))
@@ -341,7 +344,6 @@ static void migrate_page_copy(struct pag
#ifdef CONFIG_SWAP
ClearPageSwapCache(page);
#endif
- ClearPageActive(page);
ClearPagePrivate(page);
set_page_private(page, 0);
page->mapping = NULL;
Index: linux-2.6.25-rc2-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/vmscan.c 2008-02-28 00:29:55.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/vmscan.c 2008-02-28 11:05:04.000000000 -0500
@@ -480,6 +480,11 @@ static unsigned long shrink_page_list(st

sc->nr_scanned++;

+ if (!page_reclaimable(page, NULL)) {
+ SetPageNoreclaim(page);
+ goto keep_locked;
+ }
+
if (!sc->may_swap && page_mapped(page))
goto keep_locked;

@@ -582,7 +587,7 @@ static unsigned long shrink_page_list(st
* possible for a page to have PageDirty set, but it is actually
* clean (all its buffers are clean). This happens if the
* buffers were written out directly, with submit_bh(). ext3
- * will do this, as well as the blockdev mapping.
+ * will do this, as well as the blockdev mapping.
* try_to_release_page() will discover that cleanness and will
* drop the buffers and mark the page clean - it can be freed.
*
@@ -614,6 +619,7 @@ activate_locked:
/* Not a candidate for swapping, so reclaim swap space. */
if (PageSwapCache(page) && vm_swap_full())
remove_exclusive_swap_page(page);
+ VM_BUG_ON(PageActive(page));
SetPageActive(page);
pgactivate++;
keep_locked:
@@ -664,6 +670,14 @@ int __isolate_lru_page(struct page *page
if (mode != ISOLATE_BOTH && (!page_file_cache(page) != !file))
return ret;

+ /*
+ * Non-reclaimable pages shouldn't make it onto either the active
+ * nor the inactive list. However, when doing lumpy reclaim of
+ * higher order pages we can still run into them.
+ */
+ if (PageNoreclaim(page))
+ return ret;
+
ret = -EBUSY;
if (likely(get_page_unless_zero(page))) {
/*
@@ -775,7 +789,7 @@ static unsigned long isolate_lru_pages(u
/* else it is being freed elsewhere */
list_move(&cursor_page->lru, src);
default:
- break;
+ break; /* ! on LRU or wrong list */
}
}
}
@@ -831,9 +845,10 @@ static unsigned long clear_active_flags(
* refcount on the page, which is a fundamentnal difference from
* isolate_lru_pages (which is called without a stable reference).
*
- * The returned page will have PageLru() cleared, and PageActive set,
- * if it was found on the active list. This flag generally will need to be
- * cleared by the caller before letting the page go.
+ * The returned page will have the PageLru() cleared, and the PageActive or
+ * PageNoreclaim will be set, if it was found on the active or noreclaim list,
+ * respectively. This flag generally will need to be cleared by the caller
+ * before letting the page go.
*
* The vmstat page counts corresponding to the list on which the page was
* found will be decremented.
@@ -857,7 +872,13 @@ int isolate_lru_page(struct page *page)
ret = 0;
ClearPageLRU(page);

+ /* Calculate the LRU list for normal pages ... */
lru += page_file_cache(page) + !!PageActive(page);
+
+ /* ... except NoReclaim, which has its own list. */
+ if (PageNoreclaim(page))
+ lru = LRU_NORECLAIM;
+
del_page_from_lru_list(zone, page, lru);
}
spin_unlock_irq(&zone->lru_lock);
@@ -974,16 +995,21 @@ static unsigned long shrink_inactive_lis
VM_BUG_ON(PageLRU(page));
SetPageLRU(page);
list_del(&page->lru);
- if (page_file_cache(page))
- lru += LRU_FILE;
- if (scan_global_lru(sc)) {
+ if (PageNoreclaim(page)) {
+ VM_BUG_ON(PageActive(page));
+ lru = LRU_NORECLAIM;
+ } else {
if (page_file_cache(page))
- zone->recent_rotated_file++;
- else
- zone->recent_rotated_anon++;
+ lru += LRU_FILE;
+ if (scan_global_lru(sc)) {
+ if (page_file_cache(page))
+ zone->recent_rotated_file++;
+ else
+ zone->recent_rotated_anon++;
+ }
+ if (PageActive(page))
+ lru += LRU_ACTIVE;
}
- if (PageActive(page))
- lru += LRU_ACTIVE;
add_page_to_lru_list(zone, page, lru);
if (!pagevec_add(&pvec, page)) {
spin_unlock_irq(&zone->lru_lock);
@@ -1082,6 +1108,13 @@ static void shrink_active_list(unsigned
cond_resched();
page = lru_to_page(&l_hold);
list_del(&page->lru);
+
+ if (!page_reclaimable(page, NULL)) {
+ /* Non-reclaimable pages go onto their own list. */
+ list_add(&page->lru, &list[LRU_NORECLAIM]);
+ continue;
+ }
+
if (page_referenced(page, 0, sc->mem_cgroup)) {
if (file)
/* Referenced file pages stay active. */
@@ -1168,6 +1201,33 @@ static void shrink_active_list(unsigned
zone->recent_rotated_anon += pgmoved;
}

+#ifdef CONFIG_NORECLAIM
+ pgmoved = 0;
+ while (!list_empty(&list[LRU_NORECLAIM])) {
+ page = lru_to_page(&list[LRU_NORECLAIM]);
+ prefetchw_prev_lru_page(page, &list[LRU_NORECLAIM], flags);
+
+ VM_BUG_ON(PageLRU(page));
+ SetPageLRU(page);
+ VM_BUG_ON(!PageActive(page));
+ ClearPageActive(page);
+ VM_BUG_ON(PageNoreclaim(page));
+ SetPageNoreclaim(page);
+
+ list_move(&page->lru, &zone->list[LRU_NORECLAIM]);
+ pgmoved++;
+ if (!pagevec_add(&pvec, page)) {
+ __mod_zone_page_state(zone, NR_NORECLAIM, pgmoved);
+//TODO: count these as deactivations?
+ pgmoved = 0;
+ spin_unlock_irq(&zone->lru_lock);
+ __pagevec_release(&pvec);
+ spin_lock_irq(&zone->lru_lock);
+ }
+ }
+ __mod_zone_page_state(zone, NR_NORECLAIM, pgmoved);
+#endif
+
__count_zone_vm_events(PGREFILL, zone, pgscanned);
__count_vm_events(PGDEACTIVATE, pgdeactivate);
spin_unlock_irq(&zone->lru_lock);
@@ -1284,7 +1344,7 @@ static unsigned long shrink_zone(int pri

get_scan_ratio(zone, sc, percent);

- for_each_lru(l) {
+ for_each_reclaimable_lru(l) {
if (scan_global_lru(sc)) {
int file = is_file_lru(l);
int scan;
@@ -1315,7 +1375,7 @@ static unsigned long shrink_zone(int pri

while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
nr[LRU_INACTIVE_FILE]) {
- for_each_lru(l) {
+ for_each_reclaimable_lru(l) {
if (nr[l]) {
nr_to_scan = min(nr[l],
(unsigned long)sc->swap_cluster_max);
@@ -1871,8 +1931,8 @@ static unsigned long shrink_all_zones(un
if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
continue;

- for_each_lru(l) {
- /* For pass = 0 we don't shrink the active list */
+ for_each_reclaimable_lru(l) {
+ /* For pass = 0, we don't shrink the active list */
if (pass == 0 &&
(l == LRU_ACTIVE_ANON || l == LRU_ACTIVE_FILE))
continue;
@@ -2210,3 +2270,29 @@ int zone_reclaim(struct zone *zone, gfp_
return ret;
}
#endif
+
+#ifdef CONFIG_NORECLAIM
+/*
+ * page_reclaimable(struct page *page, struct vm_area_struct *vma)
+ * Test whether page is reclaimable--i.e., should be placed on active/inactive
+ * lists vs noreclaim list.
+ *
+ * @page - page to test
+ * @vma - vm area in which page is/will be mapped. May be NULL.
+ * If !NULL, called from fault path.
+ *
+ * Reasons page might not be reclaimable:
+ * TODO - later patches
+ *
+ * TODO: specify locking assumptions
+ */
+int page_reclaimable(struct page *page, struct vm_area_struct *vma)
+{
+
+ VM_BUG_ON(PageNoreclaim(page));
+
+ /* TODO: test page [!]reclaimable conditions */
+
+ return 1;
+}
+#endif
Index: linux-2.6.25-rc2-mm1/mm/mempolicy.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/mempolicy.c 2008-02-25 17:10:54.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/mempolicy.c 2008-02-28 11:05:04.000000000 -0500
@@ -1922,7 +1922,7 @@ static void gather_stats(struct page *pa
if (PageSwapCache(page))
md->swapcache++;

- if (PageActive(page))
+ if (PageActive(page) || PageNoreclaim(page))
md->active++;

if (PageWriteback(page))
Index: linux-2.6.25-rc2-mm1/mm/memcontrol.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/memcontrol.c 2008-02-28 00:27:41.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/memcontrol.c 2008-02-28 11:05:04.000000000 -0500
@@ -519,6 +519,10 @@ unsigned long mem_cgroup_isolate_pages(u
scan++;
list_move(&pc->lru, &pc_list);

+//TODO: for now, don't isolate non-reclaimable pages. When/if
+// mem controller supports a noreclaim list, we'll need to make
+// at least ISOLATE_ACTIVE visible outside of vm_scan and pass
+// the 'take_nonreclaimable' flag accordingly.
if (__isolate_lru_page(page, mode, file) == 0) {
list_move(&page->lru, dst);
nr_taken++;
--
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