migrate_pagevec() does the same job as migrate_pages() but it works with
chained page vector instead of list of isolated pages.
Signed-off-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
---
include/linux/migrate.h | 4 ++
mm/migrate.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 102 insertions(+)
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index cac1c09..04553f5 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -33,6 +33,10 @@ extern int migrate_page(struct address_space *,
struct page *, struct page *, enum migrate_mode);
extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
unsigned long private, enum migrate_mode mode, int reason);
+struct pagevec;
+extern int migrate_pagevec(struct pagevec *pages, new_page_t get_new_page,
+ free_page_t put_new_page, unsigned long private,
+ enum migrate_mode mode, int reason);
extern int migrate_prep(void);
extern int migrate_prep_local(void);
diff --git a/mm/migrate.c b/mm/migrate.c
index eca80b3..775cc9d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1153,6 +1153,104 @@ out:
return rc;
}
+/*
+ * migrate_pagevec - migrate the pages specified in a page vector, to the free
+ * pages supplied as the target for the page migration
+ *
+ * @pages: The vector of pages to be migrated.
+ * @get_new_page: The function used to allocate free pages to be used
+ * as the target of the page migration.
+ * @put_new_page: The function used to free target pages if migration
+ * fails, or NULL if no special handling is necessary.
+ * @private: Private data to be passed on to get_new_page()
+ * @mode: The migration mode that specifies the constraints for
+ * page migration, if any.
+ * @reason: The reason for page migration.
+ *
+ * The function returns after 10 attempts or if no pages are movable any more
+ * because the vector has become empty or no retryable pages exist any more.
+ * This function keeps all pages in the page vector but reorders them.
+ *
+ * Returns the number of pages that were not migrated, or an error code.
+ */
+int migrate_pagevec(struct pagevec *pages, new_page_t get_new_page,
+ free_page_t put_new_page, unsigned long private,
+ enum migrate_mode mode, int reason)
+{
+ int nr_to_scan = INT_MAX;
+ int nr_failed = 0;
+ int nr_succeeded = 0;
+ int nr_retry, pass;
+ struct page *page;
+ int swapwrite = current->flags & PF_SWAPWRITE;
+ int rc;
+
+ if (!swapwrite)
+ current->flags |= PF_SWAPWRITE;
+
+ for (pass = 0; pass < 10 && nr_to_scan; pass++) {
+ struct pagevec *pvec, *retry_pvec = pages;
+ int index, retry_index = 0;
+
+ nr_retry = 0;
+ pagevec_for_each_vec_and_page(pages, pvec, index, page) {
+ cond_resched();
+
+ if (!nr_to_scan--)
+ goto next_pass;
+
+ if (PageHuge(page))
+ rc = unmap_and_move_huge_page(get_new_page,
+ put_new_page, private, page,
+ pass > 2, mode);
+ else
+ rc = unmap_and_move(get_new_page, put_new_page,
+ private, page, pass > 2, mode);
+
+ switch(rc) {
+ case -ENOMEM:
+ goto out;
+ case -EAGAIN:
+ nr_retry++;
+ /* move page to the head for next pass */
+ swap(pvec->pages[index],
+ retry_pvec->pages[retry_index]);
+ if (++retry_index == retry_pvec->nr) {
+ retry_pvec = pagevec_next(retry_pvec);
+ retry_index = 0;
+ }
+ break;
+ case MIGRATEPAGE_SUCCESS:
+ nr_succeeded++;
+ break;
+ default:
+ /*
+ * Permanent failure (-EBUSY, -ENOSYS, etc.):
+ * unlike -EAGAIN case, the failed page is
+ * removed from migration page list and not
+ * retried in the next outer loop.
+ */
+ nr_failed++;
+ break;
+ }
+ }
+next_pass:
+ nr_to_scan = nr_retry;
+ }
+ rc = nr_failed + nr_retry;
+out:
+ if (nr_succeeded)
+ count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
+ if (nr_failed)
+ count_vm_events(PGMIGRATE_FAIL, nr_failed);
+ trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason);
+
+ if (!swapwrite)
+ current->flags &= ~PF_SWAPWRITE;
+
+ return rc;
+}
+
#ifdef CONFIG_NUMA
/*
* Move a list of individual pages
--
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