From: Zi Yan <ziy@xxxxxxxxxx>
It unmaps two lists of pages, then exchange them in
exchange_page_lists_mthread(), and finally remaps both lists of
pages.
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
include/linux/exchange.h | 2 +
mm/exchange.c | 397 +++++++++++++++++++++++++++++++++++++++++++++++
mm/exchange_page.c | 1 -
3 files changed, 399 insertions(+), 1 deletion(-)
diff --git a/include/linux/exchange.h b/include/linux/exchange.h
index 778068e..20d2184 100644
--- a/include/linux/exchange.h
+++ b/include/linux/exchange.h
@@ -20,4 +20,6 @@ struct exchange_page_info {
int exchange_pages(struct list_head *exchange_list,
enum migrate_mode mode,
int reason);
+int exchange_pages_concur(struct list_head *exchange_list,
+ enum migrate_mode mode, int reason);
#endif /* _LINUX_EXCHANGE_H */
diff --git a/mm/exchange.c b/mm/exchange.c
index ce2c899..bbada58 100644
--- a/mm/exchange.c
+++ b/mm/exchange.c
@@ -600,3 +600,400 @@ int exchange_pages(struct list_head *exchange_list,
}
return failed;
}
+
+
+static int unmap_pair_pages_concur(struct exchange_page_info *one_pair,
+ int force, enum migrate_mode mode)
+{
+ int rc = -EAGAIN;
+ struct anon_vma *anon_vma_from_page = NULL, *anon_vma_to_page = NULL;
+ struct page *from_page = one_pair->from_page;
+ struct page *to_page = one_pair->to_page;
+
+ /* from_page lock down */
+ if (!trylock_page(from_page)) {
+ if (!force || ((mode & MIGRATE_MODE_MASK) == MIGRATE_ASYNC))
+ goto out;
+
+ lock_page(from_page);
+ }
+
+ BUG_ON(PageWriteback(from_page));
+
+ /*
+ * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
+ * we cannot notice that anon_vma is freed while we migrates a page.
+ * This get_anon_vma() delays freeing anon_vma pointer until the end
+ * of migration. File cache pages are no problem because of page_lock()
+ * File Caches may use write_page() or lock_page() in migration, then,
+ * just care Anon page here.
+ *
+ * Only page_get_anon_vma() understands the subtleties of
+ * getting a hold on an anon_vma from outside one of its mms.
+ * But if we cannot get anon_vma, then we won't need it anyway,
+ * because that implies that the anon page is no longer mapped
+ * (and cannot be remapped so long as we hold the page lock).
+ */
+ if (PageAnon(from_page) && !PageKsm(from_page))
+ one_pair->from_anon_vma = anon_vma_from_page
+ = page_get_anon_vma(from_page);
+
+ /* to_page lock down */
+ if (!trylock_page(to_page)) {
+ if (!force || ((mode & MIGRATE_MODE_MASK) == MIGRATE_ASYNC))
+ goto out_unlock;
+
+ lock_page(to_page);
+ }
+
+ BUG_ON(PageWriteback(to_page));
+
+ /*
+ * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
+ * we cannot notice that anon_vma is freed while we migrates a page.
+ * This get_anon_vma() delays freeing anon_vma pointer until the end
+ * of migration. File cache pages are no problem because of page_lock()
+ * File Caches may use write_page() or lock_page() in migration, then,
+ * just care Anon page here.
+ *
+ * Only page_get_anon_vma() understands the subtleties of
+ * getting a hold on an anon_vma from outside one of its mms.
+ * But if we cannot get anon_vma, then we won't need it anyway,
+ * because that implies that the anon page is no longer mapped
+ * (and cannot be remapped so long as we hold the page lock).
+ */
+ if (PageAnon(to_page) && !PageKsm(to_page))
+ one_pair->to_anon_vma = anon_vma_to_page = page_get_anon_vma(to_page);
+
+ /*
+ * Corner case handling:
+ * 1. When a new swap-cache page is read into, it is added to the LRU
+ * and treated as swapcache but it has no rmap yet.
+ * Calling try_to_unmap() against a page->mapping==NULL page will
+ * trigger a BUG. So handle it here.
+ * 2. An orphaned page (see truncate_complete_page) might have
+ * fs-private metadata. The page can be picked up due to memory
+ * offlining. Everywhere else except page reclaim, the page is
+ * invisible to the vm, so the page can not be migrated. So try to
+ * free the metadata, so the page can be freed.
+ */
+ if (!from_page->mapping) {
+ VM_BUG_ON_PAGE(PageAnon(from_page), from_page);
+ if (page_has_private(from_page)) {
+ try_to_free_buffers(from_page);
+ goto out_unlock_both;
+ }
+ } else if (page_mapped(from_page)) {
+ /* Establish migration ptes */
+ VM_BUG_ON_PAGE(PageAnon(from_page) && !PageKsm(from_page) &&
+ !anon_vma_from_page, from_page);
+ try_to_unmap(from_page,
+ TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+
+ one_pair->from_page_was_mapped = 1;
+ }
+
+ if (!to_page->mapping) {
+ VM_BUG_ON_PAGE(PageAnon(to_page), to_page);
+ if (page_has_private(to_page)) {
+ try_to_free_buffers(to_page);
+ goto out_unlock_both;
+ }
+ } else if (page_mapped(to_page)) {
+ /* Establish migration ptes */
+ VM_BUG_ON_PAGE(PageAnon(to_page) && !PageKsm(to_page) &&
+ !anon_vma_to_page, to_page);
+ try_to_unmap(to_page,
+ TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+
+ one_pair->to_page_was_mapped = 1;
+ }
+
+ return MIGRATEPAGE_SUCCESS;
+
+out_unlock_both:
+ if (anon_vma_to_page)
+ put_anon_vma(anon_vma_to_page);
+ unlock_page(to_page);
+out_unlock:
+ /* Drop an anon_vma reference if we took one */
+ if (anon_vma_from_page)
+ put_anon_vma(anon_vma_from_page);
+ unlock_page(from_page);
+out:
+
+ return rc;
+}
+
+static int exchange_page_mapping_concur(struct list_head *unmapped_list_ptr,
+ struct list_head *exchange_list_ptr,
+ enum migrate_mode mode)
+{
+ int rc = -EBUSY;
+ int nr_failed = 0;
+ struct address_space *to_page_mapping, *from_page_mapping;
+ struct exchange_page_info *one_pair, *one_pair2;
+
+ list_for_each_entry_safe(one_pair, one_pair2, unmapped_list_ptr, list) {
+ struct page *from_page = one_pair->from_page;
+ struct page *to_page = one_pair->to_page;
+
+ VM_BUG_ON_PAGE(!PageLocked(from_page), from_page);
+ VM_BUG_ON_PAGE(!PageLocked(to_page), to_page);
+
+ /* copy page->mapping not use page_mapping() */
+ to_page_mapping = page_mapping(to_page);
+ from_page_mapping = page_mapping(from_page);
+
+ BUG_ON(from_page_mapping);
+ BUG_ON(to_page_mapping);
+
+ BUG_ON(PageWriteback(from_page));
+ BUG_ON(PageWriteback(to_page));
+
+ /* actual page mapping exchange */
+ rc = exchange_page_move_mapping(to_page_mapping, from_page_mapping,
+ to_page, from_page, mode, 0, 0);
+
+ if (rc) {
+ if (one_pair->from_page_was_mapped)
+ remove_migration_ptes(from_page, from_page, false);
+ if (one_pair->to_page_was_mapped)
+ remove_migration_ptes(to_page, to_page, false);
+
+ if (one_pair->from_anon_vma)
+ put_anon_vma(one_pair->from_anon_vma);
+ unlock_page(from_page);
+
+ if (one_pair->to_anon_vma)
+ put_anon_vma(one_pair->to_anon_vma);
+ unlock_page(to_page);
+
+ mod_node_page_state(page_pgdat(from_page), NR_ISOLATED_ANON +
+ page_is_file_cache(from_page), -hpage_nr_pages(from_page));
+ putback_lru_page(from_page);
+
+ mod_node_page_state(page_pgdat(to_page), NR_ISOLATED_ANON +
+ page_is_file_cache(to_page), -hpage_nr_pages(to_page));
+ putback_lru_page(to_page);
+
+ one_pair->from_page = NULL;
+ one_pair->to_page = NULL;
+
+ list_move(&one_pair->list, exchange_list_ptr);
+ ++nr_failed;
+ }
+ }
+
+ return nr_failed;
+}
+
+static int exchange_page_data_concur(struct list_head *unmapped_list_ptr,
+ enum migrate_mode mode)
+{
+ struct exchange_page_info *one_pair;
+ int num_pages = 0, idx = 0;
+ struct page **src_page_list = NULL, **dst_page_list = NULL;
+ unsigned long size = 0;
+ int rc = -EFAULT;
+
+ if (list_empty(unmapped_list_ptr))
+ return 0;
+
+ /* form page list */
+ list_for_each_entry(one_pair, unmapped_list_ptr, list) {
+ ++num_pages;
+ size += PAGE_SIZE * hpage_nr_pages(one_pair->from_page);
+ }
+
+ src_page_list = kzalloc(sizeof(struct page *)*num_pages, GFP_KERNEL);
+ if (!src_page_list)
+ return -ENOMEM;
+ dst_page_list = kzalloc(sizeof(struct page *)*num_pages, GFP_KERNEL);
+ if (!dst_page_list)
+ return -ENOMEM;
+
+ list_for_each_entry(one_pair, unmapped_list_ptr, list) {
+ src_page_list[idx] = one_pair->from_page;
+ dst_page_list[idx] = one_pair->to_page;
+ ++idx;
+ }
+
+ BUG_ON(idx != num_pages);
+
+
+ if (mode & MIGRATE_MT)
+ rc = exchange_page_lists_mthread(dst_page_list, src_page_list,
+ num_pages);
+
+ if (rc) {
+ list_for_each_entry(one_pair, unmapped_list_ptr, list) {
+ if (PageHuge(one_pair->from_page) ||
+ PageTransHuge(one_pair->from_page)) {
+ exchange_huge_page(one_pair->to_page, one_pair->from_page);
+ } else {
+ exchange_highpage(one_pair->to_page, one_pair->from_page);
+ }
+ }
+ }
+
+ kfree(src_page_list);
+ kfree(dst_page_list);
+
+ list_for_each_entry(one_pair, unmapped_list_ptr, list) {
+ exchange_page_flags(one_pair->to_page, one_pair->from_page);
+ }
+
+ return rc;
+}
+
+static int remove_migration_ptes_concur(struct list_head *unmapped_list_ptr)
+{
+ struct exchange_page_info *iterator;
+
+ list_for_each_entry(iterator, unmapped_list_ptr, list) {
+ remove_migration_ptes(iterator->from_page, iterator->to_page, false);
+ remove_migration_ptes(iterator->to_page, iterator->from_page, false);
+
+
+ if (iterator->from_anon_vma)
+ put_anon_vma(iterator->from_anon_vma);
+ unlock_page(iterator->from_page);
+
+
+ if (iterator->to_anon_vma)
+ put_anon_vma(iterator->to_anon_vma);
+ unlock_page(iterator->to_page);
+
+
+ putback_lru_page(iterator->from_page);
+ iterator->from_page = NULL;
+
+ putback_lru_page(iterator->to_page);
+ iterator->to_page = NULL;
+ }
+
+ return 0;
+}
+
+int exchange_pages_concur(struct list_head *exchange_list,
+ enum migrate_mode mode, int reason)
+{
+ struct exchange_page_info *one_pair, *one_pair2;
+ int pass = 0;
+ int retry = 1;
+ int nr_failed = 0;
+ int nr_succeeded = 0;
+ int rc = 0;
+ LIST_HEAD(serialized_list);
+ LIST_HEAD(unmapped_list);
+
+ for(pass = 0; pass < 1 && retry; pass++) {
+ retry = 0;
+
+ /* unmap and get new page for page_mapping(page) == NULL */
+ list_for_each_entry_safe(one_pair, one_pair2, exchange_list, list) {
+ struct page *from_page = one_pair->from_page;
+ struct page *to_page = one_pair->to_page;
+ cond_resched();
+
+ if (page_count(from_page) == 1) {
+ /* page was freed from under us. So we are done */
+ ClearPageActive(from_page);
+ ClearPageUnevictable(from_page);
+
+ put_page(from_page);
+ dec_node_page_state(from_page, NR_ISOLATED_ANON +
+ page_is_file_cache(from_page));
+
+ if (page_count(to_page) == 1) {
+ ClearPageActive(to_page);
+ ClearPageUnevictable(to_page);
+ put_page(to_page);
+ } else {
+ mod_node_page_state(page_pgdat(to_page), NR_ISOLATED_ANON +
+ page_is_file_cache(to_page), -hpage_nr_pages(to_page));
+ putback_lru_page(to_page);
+ }
+ list_del(&one_pair->list);
+
+ continue;
+ }
+
+ if (page_count(to_page) == 1) {
+ /* page was freed from under us. So we are done */
+ ClearPageActive(to_page);
+ ClearPageUnevictable(to_page);
+
+ put_page(to_page);
+
+ dec_node_page_state(to_page, NR_ISOLATED_ANON +
+ page_is_file_cache(to_page));
+
+ mod_node_page_state(page_pgdat(from_page), NR_ISOLATED_ANON +
+ page_is_file_cache(from_page), -hpage_nr_pages(from_page));
+ putback_lru_page(from_page);
+
+ list_del(&one_pair->list);
+ continue;
+ }
+ /* We do not exchange huge pages and file-backed pages concurrently */
+ if (PageHuge(one_pair->from_page) || PageHuge(one_pair->to_page)) {
+ rc = -ENODEV;
+ }
+ else if ((page_mapping(one_pair->from_page) != NULL) ||
+ (page_mapping(one_pair->from_page) != NULL)) {
+ rc = -ENODEV;
+ }
+ else
+ rc = unmap_pair_pages_concur(one_pair, 1, mode);
+
+ switch(rc) {
+ case -ENODEV:
+ list_move(&one_pair->list, &serialized_list);
+ break;
+ case -ENOMEM:
+ goto out;
+ case -EAGAIN:
+ retry++;
+ break;
+ case MIGRATEPAGE_SUCCESS:
+ list_move(&one_pair->list, &unmapped_list);
+ 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.
+ */
+ list_move(&one_pair->list, &serialized_list);
+ nr_failed++;
+ break;
+ }
+ }
+
+ /* move page->mapping to new page, only -EAGAIN could happen */
+ exchange_page_mapping_concur(&unmapped_list, exchange_list, mode);
+
+
+ /* copy pages in unmapped_list */
+ exchange_page_data_concur(&unmapped_list, mode);
+
+
+ /* remove migration pte, if old_page is NULL?, unlock old and new
+ * pages, put anon_vma, put old and new pages */
+ remove_migration_ptes_concur(&unmapped_list);
+ }
+
+ nr_failed += retry;
+ rc = nr_failed;
+
+ exchange_pages(&serialized_list, mode, reason);
+out:
+ list_splice(&unmapped_list, exchange_list);
+ list_splice(&serialized_list, exchange_list);
+
+ return nr_failed?-EFAULT:0;
+}
diff --git a/mm/exchange_page.c b/mm/exchange_page.c
index 6054697..5dba0a6 100644
--- a/mm/exchange_page.c
+++ b/mm/exchange_page.c
@@ -126,7 +126,6 @@ int exchange_page_lists_mthread(struct page **to, struct page **from, int nr_pag
int to_node = page_to_nid(*to);
int i;
struct copy_page_info *work_items;
- int nr_pages_per_page = hpage_nr_pages(*from);
const struct cpumask *per_node_cpumask = cpumask_of_node(to_node);
int cpu_id_list[32] = {0};
int cpu;
--
2.7.4
