mm: compaction: introduce sync-light migration for use by compaction
This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT mode that avoids writing back pages to backing storage. Async compaction maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT. For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is used. This avoids sync compaction stalling for an excessive length of time, particularly when copying files to a USB stick where there might be a large number of dirty pages backed by a filesystem that does not support ->writepages. [aarcange@redhat.com: This patch is heavily based on Andrea's work] [akpm@linux-foundation.org: fix fs/nfs/write.c build] [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build] Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Andy Isaacson <adi@hexapodia.org> Cc: Nai Xia <nai.xia@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman
Linus Torvalds
Родитель
66199712e9
Коммит
a6bc32b899
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@ -872,7 +872,8 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
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#ifdef CONFIG_MIGRATION
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static int btree_migratepage(struct address_space *mapping,
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struct page *newpage, struct page *page, bool sync)
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struct page *newpage, struct page *page,
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enum migrate_mode mode)
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{
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/*
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* we can't safely write a btree page from here,
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@ -887,7 +888,7 @@ static int btree_migratepage(struct address_space *mapping,
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if (page_has_private(page) &&
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!try_to_release_page(page, GFP_KERNEL))
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return -EAGAIN;
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return migrate_page(mapping, newpage, page, sync);
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return migrate_page(mapping, newpage, page, mode);
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}
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#endif
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@ -584,7 +584,7 @@ static int hugetlbfs_set_page_dirty(struct page *page)
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static int hugetlbfs_migrate_page(struct address_space *mapping,
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struct page *newpage, struct page *page,
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bool sync)
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enum migrate_mode mode)
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{
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int rc;
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@ -332,7 +332,7 @@ void nfs_commit_release_pages(struct nfs_write_data *data);
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#ifdef CONFIG_MIGRATION
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extern int nfs_migrate_page(struct address_space *,
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struct page *, struct page *, bool);
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struct page *, struct page *, enum migrate_mode);
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#else
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#define nfs_migrate_page NULL
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#endif
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@ -1688,7 +1688,7 @@ out_error:
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#ifdef CONFIG_MIGRATION
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int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
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struct page *page, bool sync)
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struct page *page, enum migrate_mode mode)
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{
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/*
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* If PagePrivate is set, then the page is currently associated with
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@ -1703,7 +1703,7 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
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nfs_fscache_release_page(page, GFP_KERNEL);
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return migrate_page(mapping, newpage, page, sync);
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return migrate_page(mapping, newpage, page, mode);
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}
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#endif
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@ -525,6 +525,7 @@ enum positive_aop_returns {
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struct page;
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struct address_space;
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struct writeback_control;
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enum migrate_mode;
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struct iov_iter {
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const struct iovec *iov;
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@ -614,7 +615,7 @@ struct address_space_operations {
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* is false, it must not block.
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*/
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int (*migratepage) (struct address_space *,
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struct page *, struct page *, bool);
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struct page *, struct page *, enum migrate_mode);
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int (*launder_page) (struct page *);
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int (*is_partially_uptodate) (struct page *, read_descriptor_t *,
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unsigned long);
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@ -2540,7 +2541,8 @@ extern int generic_check_addressable(unsigned, u64);
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#ifdef CONFIG_MIGRATION
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extern int buffer_migrate_page(struct address_space *,
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struct page *, struct page *, bool);
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struct page *, struct page *,
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enum migrate_mode);
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#else
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#define buffer_migrate_page NULL
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#endif
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@ -6,18 +6,31 @@
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typedef struct page *new_page_t(struct page *, unsigned long private, int **);
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/*
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* MIGRATE_ASYNC means never block
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* MIGRATE_SYNC_LIGHT in the current implementation means to allow blocking
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* on most operations but not ->writepage as the potential stall time
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* is too significant
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* MIGRATE_SYNC will block when migrating pages
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*/
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enum migrate_mode {
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MIGRATE_ASYNC,
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MIGRATE_SYNC_LIGHT,
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MIGRATE_SYNC,
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};
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#ifdef CONFIG_MIGRATION
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#define PAGE_MIGRATION 1
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extern void putback_lru_pages(struct list_head *l);
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extern int migrate_page(struct address_space *,
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struct page *, struct page *, bool);
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struct page *, struct page *, enum migrate_mode);
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extern int migrate_pages(struct list_head *l, new_page_t x,
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unsigned long private, bool offlining,
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bool sync);
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enum migrate_mode mode);
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extern int migrate_huge_pages(struct list_head *l, new_page_t x,
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unsigned long private, bool offlining,
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bool sync);
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enum migrate_mode mode);
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extern int fail_migrate_page(struct address_space *,
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struct page *, struct page *);
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@ -36,10 +49,10 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
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static inline void putback_lru_pages(struct list_head *l) {}
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static inline int migrate_pages(struct list_head *l, new_page_t x,
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unsigned long private, bool offlining,
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bool sync) { return -ENOSYS; }
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enum migrate_mode mode) { return -ENOSYS; }
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static inline int migrate_huge_pages(struct list_head *l, new_page_t x,
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unsigned long private, bool offlining,
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bool sync) { return -ENOSYS; }
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enum migrate_mode mode) { return -ENOSYS; }
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static inline int migrate_prep(void) { return -ENOSYS; }
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static inline int migrate_prep_local(void) { return -ENOSYS; }
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@ -557,7 +557,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
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nr_migrate = cc->nr_migratepages;
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err = migrate_pages(&cc->migratepages, compaction_alloc,
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(unsigned long)cc, false,
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cc->sync);
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cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC);
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update_nr_listpages(cc);
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nr_remaining = cc->nr_migratepages;
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@ -1557,7 +1557,7 @@ int soft_offline_page(struct page *page, int flags)
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page_is_file_cache(page));
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list_add(&page->lru, &pagelist);
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ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
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0, true);
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0, MIGRATE_SYNC);
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if (ret) {
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putback_lru_pages(&pagelist);
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pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
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@ -809,7 +809,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
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}
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/* this function returns # of failed pages */
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ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
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true, true);
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true, MIGRATE_SYNC);
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if (ret)
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putback_lru_pages(&source);
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}
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@ -942,7 +942,7 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
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if (!list_empty(&pagelist)) {
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err = migrate_pages(&pagelist, new_node_page, dest,
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false, true);
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false, MIGRATE_SYNC);
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if (err)
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putback_lru_pages(&pagelist);
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}
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78
mm/migrate.c
78
mm/migrate.c
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@ -218,12 +218,13 @@ out:
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#ifdef CONFIG_BLOCK
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/* Returns true if all buffers are successfully locked */
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static bool buffer_migrate_lock_buffers(struct buffer_head *head, bool sync)
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static bool buffer_migrate_lock_buffers(struct buffer_head *head,
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enum migrate_mode mode)
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{
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struct buffer_head *bh = head;
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/* Simple case, sync compaction */
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if (sync) {
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if (mode != MIGRATE_ASYNC) {
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do {
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get_bh(bh);
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lock_buffer(bh);
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@ -259,7 +260,7 @@ static bool buffer_migrate_lock_buffers(struct buffer_head *head, bool sync)
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}
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#else
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static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
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bool sync)
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enum migrate_mode mode)
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{
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return true;
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}
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@ -275,7 +276,7 @@ static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
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*/
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static int migrate_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page,
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struct buffer_head *head, bool sync)
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struct buffer_head *head, enum migrate_mode mode)
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{
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int expected_count;
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void **pslot;
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@ -311,7 +312,8 @@ static int migrate_page_move_mapping(struct address_space *mapping,
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* the mapping back due to an elevated page count, we would have to
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* block waiting on other references to be dropped.
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*/
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if (!sync && head && !buffer_migrate_lock_buffers(head, sync)) {
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if (mode == MIGRATE_ASYNC && head &&
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!buffer_migrate_lock_buffers(head, mode)) {
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page_unfreeze_refs(page, expected_count);
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spin_unlock_irq(&mapping->tree_lock);
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return -EAGAIN;
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@ -472,13 +474,14 @@ EXPORT_SYMBOL(fail_migrate_page);
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* Pages are locked upon entry and exit.
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*/
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int migrate_page(struct address_space *mapping,
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struct page *newpage, struct page *page, bool sync)
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struct page *newpage, struct page *page,
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enum migrate_mode mode)
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{
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int rc;
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BUG_ON(PageWriteback(page)); /* Writeback must be complete */
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rc = migrate_page_move_mapping(mapping, newpage, page, NULL, sync);
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rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode);
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if (rc)
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return rc;
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@ -495,17 +498,17 @@ EXPORT_SYMBOL(migrate_page);
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* exist.
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*/
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int buffer_migrate_page(struct address_space *mapping,
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struct page *newpage, struct page *page, bool sync)
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struct page *newpage, struct page *page, enum migrate_mode mode)
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{
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struct buffer_head *bh, *head;
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int rc;
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if (!page_has_buffers(page))
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return migrate_page(mapping, newpage, page, sync);
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return migrate_page(mapping, newpage, page, mode);
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head = page_buffers(page);
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rc = migrate_page_move_mapping(mapping, newpage, page, head, sync);
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rc = migrate_page_move_mapping(mapping, newpage, page, head, mode);
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if (rc)
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return rc;
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@ -515,8 +518,8 @@ int buffer_migrate_page(struct address_space *mapping,
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* with an IRQ-safe spinlock held. In the sync case, the buffers
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* need to be locked now
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*/
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if (sync)
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BUG_ON(!buffer_migrate_lock_buffers(head, sync));
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if (mode != MIGRATE_ASYNC)
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BUG_ON(!buffer_migrate_lock_buffers(head, mode));
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ClearPagePrivate(page);
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set_page_private(newpage, page_private(page));
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@ -593,10 +596,11 @@ static int writeout(struct address_space *mapping, struct page *page)
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* Default handling if a filesystem does not provide a migration function.
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*/
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static int fallback_migrate_page(struct address_space *mapping,
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struct page *newpage, struct page *page, bool sync)
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struct page *newpage, struct page *page, enum migrate_mode mode)
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{
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if (PageDirty(page)) {
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if (!sync)
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/* Only writeback pages in full synchronous migration */
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if (mode != MIGRATE_SYNC)
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return -EBUSY;
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return writeout(mapping, page);
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}
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@ -609,7 +613,7 @@ static int fallback_migrate_page(struct address_space *mapping,
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!try_to_release_page(page, GFP_KERNEL))
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return -EAGAIN;
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return migrate_page(mapping, newpage, page, sync);
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return migrate_page(mapping, newpage, page, mode);
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}
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/*
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@ -624,7 +628,7 @@ static int fallback_migrate_page(struct address_space *mapping,
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* == 0 - success
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*/
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static int move_to_new_page(struct page *newpage, struct page *page,
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int remap_swapcache, bool sync)
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int remap_swapcache, enum migrate_mode mode)
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{
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struct address_space *mapping;
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int rc;
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@ -645,7 +649,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
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mapping = page_mapping(page);
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if (!mapping)
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rc = migrate_page(mapping, newpage, page, sync);
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rc = migrate_page(mapping, newpage, page, mode);
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else if (mapping->a_ops->migratepage)
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/*
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* Most pages have a mapping and most filesystems provide a
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@ -654,9 +658,9 @@ static int move_to_new_page(struct page *newpage, struct page *page,
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* is the most common path for page migration.
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*/
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rc = mapping->a_ops->migratepage(mapping,
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newpage, page, sync);
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newpage, page, mode);
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else
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rc = fallback_migrate_page(mapping, newpage, page, sync);
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rc = fallback_migrate_page(mapping, newpage, page, mode);
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if (rc) {
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newpage->mapping = NULL;
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@ -671,7 +675,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
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}
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static int __unmap_and_move(struct page *page, struct page *newpage,
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int force, bool offlining, bool sync)
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int force, bool offlining, enum migrate_mode mode)
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{
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int rc = -EAGAIN;
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int remap_swapcache = 1;
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@ -680,7 +684,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
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struct anon_vma *anon_vma = NULL;
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if (!trylock_page(page)) {
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if (!force || !sync)
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if (!force || mode == MIGRATE_ASYNC)
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goto out;
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/*
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@ -726,10 +730,12 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
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if (PageWriteback(page)) {
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/*
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* For !sync, there is no point retrying as the retry loop
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* is expected to be too short for PageWriteback to be cleared
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* Only in the case of a full syncronous migration is it
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* necessary to wait for PageWriteback. In the async case,
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* the retry loop is too short and in the sync-light case,
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* the overhead of stalling is too much
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*/
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if (!sync) {
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if (mode != MIGRATE_SYNC) {
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rc = -EBUSY;
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goto uncharge;
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}
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@ -800,7 +806,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
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skip_unmap:
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if (!page_mapped(page))
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rc = move_to_new_page(newpage, page, remap_swapcache, sync);
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rc = move_to_new_page(newpage, page, remap_swapcache, mode);
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if (rc && remap_swapcache)
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remove_migration_ptes(page, page);
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@ -823,7 +829,8 @@ out:
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* to the newly allocated page in newpage.
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*/
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static int unmap_and_move(new_page_t get_new_page, unsigned long private,
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struct page *page, int force, bool offlining, bool sync)
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struct page *page, int force, bool offlining,
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enum migrate_mode mode)
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{
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int rc = 0;
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int *result = NULL;
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@ -843,7 +850,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
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if (unlikely(split_huge_page(page)))
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goto out;
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rc = __unmap_and_move(page, newpage, force, offlining, sync);
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rc = __unmap_and_move(page, newpage, force, offlining, mode);
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out:
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if (rc != -EAGAIN) {
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/*
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|
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@ -891,7 +898,8 @@ out:
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*/
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static int unmap_and_move_huge_page(new_page_t get_new_page,
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unsigned long private, struct page *hpage,
|
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int force, bool offlining, bool sync)
|
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int force, bool offlining,
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enum migrate_mode mode)
|
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{
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int rc = 0;
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int *result = NULL;
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|
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@ -904,7 +912,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
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rc = -EAGAIN;
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if (!trylock_page(hpage)) {
|
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if (!force || !sync)
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if (!force || mode != MIGRATE_SYNC)
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goto out;
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lock_page(hpage);
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}
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@ -915,7 +923,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
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try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
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if (!page_mapped(hpage))
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rc = move_to_new_page(new_hpage, hpage, 1, sync);
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rc = move_to_new_page(new_hpage, hpage, 1, mode);
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if (rc)
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remove_migration_ptes(hpage, hpage);
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@ -958,7 +966,7 @@ out:
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*/
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int migrate_pages(struct list_head *from,
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new_page_t get_new_page, unsigned long private, bool offlining,
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bool sync)
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enum migrate_mode mode)
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{
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int retry = 1;
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int nr_failed = 0;
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@ -979,7 +987,7 @@ int migrate_pages(struct list_head *from,
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rc = unmap_and_move(get_new_page, private,
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page, pass > 2, offlining,
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sync);
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mode);
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switch(rc) {
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case -ENOMEM:
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@ -1009,7 +1017,7 @@ out:
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int migrate_huge_pages(struct list_head *from,
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new_page_t get_new_page, unsigned long private, bool offlining,
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bool sync)
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enum migrate_mode mode)
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{
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int retry = 1;
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int nr_failed = 0;
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@ -1026,7 +1034,7 @@ int migrate_huge_pages(struct list_head *from,
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rc = unmap_and_move_huge_page(get_new_page,
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private, page, pass > 2, offlining,
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sync);
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mode);
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switch(rc) {
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case -ENOMEM:
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@ -1155,7 +1163,7 @@ set_status:
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err = 0;
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if (!list_empty(&pagelist)) {
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err = migrate_pages(&pagelist, new_page_node,
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(unsigned long)pm, 0, true);
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(unsigned long)pm, 0, MIGRATE_SYNC);
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if (err)
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putback_lru_pages(&pagelist);
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}
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