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    Subject[patch 01/14] move isolate_lru_page() to vmscan.c
    From: Nick Piggin <npiggin@suse.de>

    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>

    ---

    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)

    Index: linux-2.6.26-rc2-mm1/include/linux/migrate.h
    ===================================================================
    --- linux-2.6.26-rc2-mm1.orig/include/linux/migrate.h 2007-07-08 19:32:17.000000000 -0400
    +++ linux-2.6.26-rc2-mm1/include/linux/migrate.h 2008-05-15 16:07:44.000000000 -0400
    @@ -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-2.6.26-rc2-mm1/mm/internal.h
    ===================================================================
    --- linux-2.6.26-rc2-mm1.orig/mm/internal.h 2008-05-15 11:21:11.000000000 -0400
    +++ linux-2.6.26-rc2-mm1/mm/internal.h 2008-05-15 16:07:44.000000000 -0400
    @@ -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 __free_pages_bootmem(struct page *page, unsigned int order);

    /*
    Index: linux-2.6.26-rc2-mm1/mm/migrate.c
    ===================================================================
    --- linux-2.6.26-rc2-mm1.orig/mm/migrate.c 2008-05-15 11:21:11.000000000 -0400
    +++ linux-2.6.26-rc2-mm1/mm/migrate.c 2008-05-15 16:07:44.000000000 -0400
    @@ -37,36 +37,6 @@
    #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().
    */
    @@ -895,7 +865,9 @@ 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)
    + list_add_tail(&page->lru, &pagelist);
    put_and_set:
    /*
    * Either remove the duplicate refcount from
    Index: linux-2.6.26-rc2-mm1/mm/vmscan.c
    ===================================================================
    --- linux-2.6.26-rc2-mm1.orig/mm/vmscan.c 2008-05-15 11:21:11.000000000 -0400
    +++ linux-2.6.26-rc2-mm1/mm/vmscan.c 2008-05-15 16:07:44.000000000 -0400
    @@ -816,6 +816,51 @@ static unsigned long clear_active_flags(
    return nr_active;
    }

    +/**
    + * isolate_lru_page - tries to isolate a page from its LRU list
    + * @page: page to isolate from its LRU list
    + *
    + * Isolates a @page from an LRU list, clears PageLRU and adjusts the
    + * vmstat statistic corresponding to whatever LRU list the page was on.
    + *
    + * Returns 0 if the page was removed from an LRU list.
    + * Returns -EBUSY if the page was not on an LRU list.
    + *
    + * The returned page will have PageLRU() cleared. If it was found on
    + * the active list, it will have PageActive set. That flag may need
    + * to be cleared by the caller before letting the page go.
    + *
    + * The vmstat statistic corresponding to the list on which the page was
    + * found will be decremented.
    + *
    + * Restrictions:
    + * (1) Must be called with an elevated refcount on the page. This is a
    + * fundamentnal difference from isolate_lru_pages (which is called
    + * without a stable reference).
    + * (2) the lru_lock must not be held.
    + * (3) interrupts must be enabled.
    + */
    +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-2.6.26-rc2-mm1/mm/mempolicy.c
    ===================================================================
    --- linux-2.6.26-rc2-mm1.orig/mm/mempolicy.c 2008-05-15 11:20:57.000000000 -0400
    +++ linux-2.6.26-rc2-mm1/mm/mempolicy.c 2008-05-15 16:07:44.000000000 -0400
    @@ -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 */
    @@ -758,8 +760,11 @@ 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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