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Subject[patch 01/21] move isolate_lru_page() to vmscan.c
V1 -> V2 [lts]:
+ fix botched merge -- add back "get_page_unless_zero()"

From: Nick Piggin <npiggin@suse.de>
To: Linux Memory Management <linux-mm@kvack.org>
Subject: [patch 1/4] mm: move and rework isolate_lru_page
Date: Mon, 12 Mar 2007 07:38:44 +0100 (CET)

isolate_lru_page logically belongs to be in vmscan.c than migrate.c.

It is tough, because we don't need that function without memory migration
so there is a valid argument to have it in migrate.c. However a subsequent
patch needs to make use of it in the core mm, so we can happily move it
to vmscan.c.

Also, make the function a little more generic by not requiring that it
adds an isolated page to a given list. Callers can do that.

Note that we now have '__isolate_lru_page()', that does
something quite different, visible outside of vmscan.c
for use with memory controller. Methinks we need to
rationalize these names/purposes. --lts

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

Index: linux-2.6.25-rc2-mm1/include/linux/migrate.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/include/linux/migrate.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.25-rc2-mm1/include/linux/migrate.h 2008-02-25 17:10:54.000000000 -0500
@@ -25,7 +25,6 @@ static inline int vma_migratable(struct
return 1;
}

-extern int isolate_lru_page(struct page *p, struct list_head *pagelist);
extern int putback_lru_pages(struct list_head *l);
extern int migrate_page(struct address_space *,
struct page *, struct page *);
@@ -42,8 +41,6 @@ extern int migrate_vmas(struct mm_struct
static inline int vma_migratable(struct vm_area_struct *vma)
{ return 0; }

-static inline int isolate_lru_page(struct page *p, struct list_head *list)
- { return -ENOSYS; }
static inline int putback_lru_pages(struct list_head *l) { return 0; }
static inline int migrate_pages(struct list_head *l, new_page_t x,
unsigned long private) { return -ENOSYS; }
Index: linux-2.6.25-rc2-mm1/mm/internal.h
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/internal.h 2008-02-19 16:23:09.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/internal.h 2008-02-25 17:10:54.000000000 -0500
@@ -34,6 +34,8 @@ static inline void __put_page(struct pag
atomic_dec(&page->_count);
}

+extern int isolate_lru_page(struct page *page);
+
extern void __init __free_pages_bootmem(struct page *page,
unsigned int order);

Index: linux-2.6.25-rc2-mm1/mm/migrate.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/migrate.c 2008-02-19 16:23:09.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/migrate.c 2008-02-25 17:10:54.000000000 -0500
@@ -36,36 +36,6 @@
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))

/*
- * Isolate one page from the LRU lists. If successful put it onto
- * the indicated list with elevated page count.
- *
- * Result:
- * -EBUSY: page not on LRU list
- * 0: page removed from LRU list and added to the specified list.
- */
-int isolate_lru_page(struct page *page, struct list_head *pagelist)
-{
- int ret = -EBUSY;
-
- if (PageLRU(page)) {
- struct zone *zone = page_zone(page);
-
- spin_lock_irq(&zone->lru_lock);
- if (PageLRU(page) && get_page_unless_zero(page)) {
- ret = 0;
- ClearPageLRU(page);
- if (PageActive(page))
- del_page_from_active_list(zone, page);
- else
- del_page_from_inactive_list(zone, page);
- list_add_tail(&page->lru, pagelist);
- }
- spin_unlock_irq(&zone->lru_lock);
- }
- return ret;
-}
-
-/*
* migrate_prep() needs to be called before we start compiling a list of pages
* to be migrated using isolate_lru_page().
*/
@@ -870,14 +840,17 @@ static int do_move_pages(struct mm_struc
!migrate_all)
goto put_and_set;

- err = isolate_lru_page(page, &pagelist);
+ err = isolate_lru_page(page);
+ if (err) {
put_and_set:
- /*
- * Either remove the duplicate refcount from
- * isolate_lru_page() or drop the page ref if it was
- * not isolated.
- */
- put_page(page);
+ /*
+ * Either remove the duplicate refcount from
+ * isolate_lru_page() or drop the page ref if it was
+ * not isolated.
+ */
+ put_page(page);
+ } else
+ list_add_tail(&page->lru, &pagelist);
set_status:
pp->status = err;
}
Index: linux-2.6.25-rc2-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/vmscan.c 2008-02-19 16:23:16.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/vmscan.c 2008-02-25 17:10:54.000000000 -0500
@@ -829,6 +829,47 @@ static unsigned long clear_active_flags(
return nr_active;
}

+/**
+ * isolate_lru_page(@page)
+ *
+ * Isolate one @page from the LRU lists. Must be called with an elevated
+ * 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 vmstat page counts corresponding to the list on which the page was
+ * found will be decremented.
+ *
+ * lru_lock must not be held, interrupts must be enabled.
+ *
+ * Returns:
+ * -EBUSY: page not on LRU list
+ * 0: page removed from LRU list.
+ */
+int isolate_lru_page(struct page *page)
+{
+ int ret = -EBUSY;
+
+ if (PageLRU(page)) {
+ struct zone *zone = page_zone(page);
+
+ spin_lock_irq(&zone->lru_lock);
+ if (PageLRU(page) && get_page_unless_zero(page)) {
+ ret = 0;
+ ClearPageLRU(page);
+ if (PageActive(page))
+ del_page_from_active_list(zone, page);
+ else
+ del_page_from_inactive_list(zone, page);
+ }
+ spin_unlock_irq(&zone->lru_lock);
+ }
+ return ret;
+}
+
/*
* shrink_inactive_list() is a helper for shrink_zone(). It returns the number
* of reclaimed pages
Index: linux-2.6.25-rc2-mm1/mm/mempolicy.c
===================================================================
--- linux-2.6.25-rc2-mm1.orig/mm/mempolicy.c 2008-02-19 16:23:09.000000000 -0500
+++ linux-2.6.25-rc2-mm1/mm/mempolicy.c 2008-02-25 17:10:54.000000000 -0500
@@ -93,6 +93,8 @@
#include <asm/tlbflush.h>
#include <asm/uaccess.h>

+#include "internal.h"
+
/* Internal flags */
#define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0) /* Skip checks for continuous vmas */
#define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1) /* Invert check for nodemask */
@@ -618,8 +620,11 @@ static void migrate_page_add(struct page
/*
* Avoid migrating a page that is shared with others.
*/
- if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1)
- isolate_lru_page(page, pagelist);
+ if ((flags & MPOL_MF_MOVE_ALL) || page_mapcount(page) == 1) {
+ if (!isolate_lru_page(page)) {
+ list_add_tail(&page->lru, pagelist);
+ }
+ }
}

static struct page *new_node_page(struct page *page, unsigned long node, int **x)
--
All Rights Reversed



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