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-rw-r--r--mm/migrate.c164
1 files changed, 68 insertions, 96 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 2fd8b4af474..3bbaf5d230b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -464,7 +464,10 @@ void migrate_page_copy(struct page *newpage, struct page *page)
mlock_migrate_page(newpage, page);
ksm_migrate_page(newpage, page);
-
+ /*
+ * Please do not reorder this without considering how mm/ksm.c's
+ * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
+ */
ClearPageSwapCache(page);
ClearPagePrivate(page);
set_page_private(page, 0);
@@ -698,7 +701,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
}
static int __unmap_and_move(struct page *page, struct page *newpage,
- int force, bool offlining, enum migrate_mode mode)
+ int force, enum migrate_mode mode)
{
int rc = -EAGAIN;
int remap_swapcache = 1;
@@ -728,20 +731,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
lock_page(page);
}
- /*
- * Only memory hotplug's offline_pages() caller has locked out KSM,
- * and can safely migrate a KSM page. The other cases have skipped
- * PageKsm along with PageReserved - but it is only now when we have
- * the page lock that we can be certain it will not go KSM beneath us
- * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
- * its pagecount raised, but only here do we take the page lock which
- * serializes that).
- */
- if (PageKsm(page) && !offlining) {
- rc = -EBUSY;
- goto unlock;
- }
-
/* charge against new page */
mem_cgroup_prepare_migration(page, newpage, &mem);
@@ -768,7 +757,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
* File Caches may use write_page() or lock_page() in migration, then,
* just care Anon page here.
*/
- if (PageAnon(page)) {
+ if (PageAnon(page) && !PageKsm(page)) {
/*
* Only page_lock_anon_vma_read() understands the subtleties of
* getting a hold on an anon_vma from outside one of its mms.
@@ -848,7 +837,6 @@ uncharge:
mem_cgroup_end_migration(mem, page, newpage,
(rc == MIGRATEPAGE_SUCCESS ||
rc == MIGRATEPAGE_BALLOON_SUCCESS));
-unlock:
unlock_page(page);
out:
return rc;
@@ -859,8 +847,7 @@ out:
* to the newly allocated page in newpage.
*/
static int unmap_and_move(new_page_t get_new_page, unsigned long private,
- struct page *page, int force, bool offlining,
- enum migrate_mode mode)
+ struct page *page, int force, enum migrate_mode mode)
{
int rc = 0;
int *result = NULL;
@@ -878,7 +865,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
if (unlikely(split_huge_page(page)))
goto out;
- rc = __unmap_and_move(page, newpage, force, offlining, mode);
+ rc = __unmap_and_move(page, newpage, force, mode);
if (unlikely(rc == MIGRATEPAGE_BALLOON_SUCCESS)) {
/*
@@ -938,8 +925,7 @@ out:
*/
static int unmap_and_move_huge_page(new_page_t get_new_page,
unsigned long private, struct page *hpage,
- int force, bool offlining,
- enum migrate_mode mode)
+ int force, enum migrate_mode mode)
{
int rc = 0;
int *result = NULL;
@@ -1001,9 +987,8 @@ out:
*
* Return: Number of pages not migrated or error code.
*/
-int migrate_pages(struct list_head *from,
- new_page_t get_new_page, unsigned long private, bool offlining,
- enum migrate_mode mode, int reason)
+int migrate_pages(struct list_head *from, new_page_t get_new_page,
+ unsigned long private, enum migrate_mode mode, int reason)
{
int retry = 1;
int nr_failed = 0;
@@ -1024,8 +1009,7 @@ int migrate_pages(struct list_head *from,
cond_resched();
rc = unmap_and_move(get_new_page, private,
- page, pass > 2, offlining,
- mode);
+ page, pass > 2, mode);
switch(rc) {
case -ENOMEM:
@@ -1058,15 +1042,13 @@ out:
}
int migrate_huge_page(struct page *hpage, new_page_t get_new_page,
- unsigned long private, bool offlining,
- enum migrate_mode mode)
+ unsigned long private, enum migrate_mode mode)
{
int pass, rc;
for (pass = 0; pass < 10; pass++) {
- rc = unmap_and_move_huge_page(get_new_page,
- private, hpage, pass > 2, offlining,
- mode);
+ rc = unmap_and_move_huge_page(get_new_page, private,
+ hpage, pass > 2, mode);
switch (rc) {
case -ENOMEM:
goto out;
@@ -1152,7 +1134,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
goto set_status;
/* Use PageReserved to check for zero page */
- if (PageReserved(page) || PageKsm(page))
+ if (PageReserved(page))
goto put_and_set;
pp->page = page;
@@ -1189,8 +1171,7 @@ set_status:
err = 0;
if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_page_node,
- (unsigned long)pm, 0, MIGRATE_SYNC,
- MR_SYSCALL);
+ (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL);
if (err)
putback_lru_pages(&pagelist);
}
@@ -1314,7 +1295,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
err = -ENOENT;
/* Use PageReserved to check for zero page */
- if (!page || PageReserved(page) || PageKsm(page))
+ if (!page || PageReserved(page))
goto set_status;
err = page_to_nid(page);
@@ -1461,7 +1442,7 @@ int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
* pages. Currently it only checks the watermarks which crude
*/
static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
- int nr_migrate_pages)
+ unsigned long nr_migrate_pages)
{
int z;
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
@@ -1497,7 +1478,7 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
__GFP_NOWARN) &
~GFP_IOFS, 0);
if (newpage)
- page_xchg_last_nid(newpage, page_last_nid(page));
+ page_nid_xchg_last(newpage, page_nid_last(page));
return newpage;
}
@@ -1557,39 +1538,40 @@ bool numamigrate_update_ratelimit(pg_data_t *pgdat, unsigned long nr_pages)
int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
{
- int ret = 0;
+ int page_lru;
+
+ VM_BUG_ON(compound_order(page) && !PageTransHuge(page));
/* Avoid migrating to a node that is nearly full */
- if (migrate_balanced_pgdat(pgdat, 1)) {
- int page_lru;
+ if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page)))
+ return 0;
- if (isolate_lru_page(page)) {
- put_page(page);
- return 0;
- }
+ if (isolate_lru_page(page))
+ return 0;
- /* Page is isolated */
- ret = 1;
- page_lru = page_is_file_cache(page);
- if (!PageTransHuge(page))
- inc_zone_page_state(page, NR_ISOLATED_ANON + page_lru);
- else
- mod_zone_page_state(page_zone(page),
- NR_ISOLATED_ANON + page_lru,
- HPAGE_PMD_NR);
+ /*
+ * migrate_misplaced_transhuge_page() skips page migration's usual
+ * check on page_count(), so we must do it here, now that the page
+ * has been isolated: a GUP pin, or any other pin, prevents migration.
+ * The expected page count is 3: 1 for page's mapcount and 1 for the
+ * caller's pin and 1 for the reference taken by isolate_lru_page().
+ */
+ if (PageTransHuge(page) && page_count(page) != 3) {
+ putback_lru_page(page);
+ return 0;
}
+ page_lru = page_is_file_cache(page);
+ mod_zone_page_state(page_zone(page), NR_ISOLATED_ANON + page_lru,
+ hpage_nr_pages(page));
+
/*
- * Page is either isolated or there is not enough space on the target
- * node. If isolated, then it has taken a reference count and the
- * callers reference can be safely dropped without the page
- * disappearing underneath us during migration. Otherwise the page is
- * not to be migrated but the callers reference should still be
- * dropped so it does not leak.
+ * Isolating the page has taken another reference, so the
+ * caller's reference can be safely dropped without the page
+ * disappearing underneath us during migration.
*/
put_page(page);
-
- return ret;
+ return 1;
}
/*
@@ -1600,7 +1582,7 @@ int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
int migrate_misplaced_page(struct page *page, int node)
{
pg_data_t *pgdat = NODE_DATA(node);
- int isolated = 0;
+ int isolated;
int nr_remaining;
LIST_HEAD(migratepages);
@@ -1608,42 +1590,43 @@ int migrate_misplaced_page(struct page *page, int node)
* Don't migrate pages that are mapped in multiple processes.
* TODO: Handle false sharing detection instead of this hammer
*/
- if (page_mapcount(page) != 1) {
- put_page(page);
+ if (page_mapcount(page) != 1)
goto out;
- }
/*
* Rate-limit the amount of data that is being migrated to a node.
* Optimal placement is no good if the memory bus is saturated and
* all the time is being spent migrating!
*/
- if (numamigrate_update_ratelimit(pgdat, 1)) {
- put_page(page);
+ if (numamigrate_update_ratelimit(pgdat, 1))
goto out;
- }
isolated = numamigrate_isolate_page(pgdat, page);
if (!isolated)
goto out;
list_add(&page->lru, &migratepages);
- nr_remaining = migrate_pages(&migratepages,
- alloc_misplaced_dst_page,
- node, false, MIGRATE_ASYNC,
- MR_NUMA_MISPLACED);
+ nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
+ node, MIGRATE_ASYNC, MR_NUMA_MISPLACED);
if (nr_remaining) {
putback_lru_pages(&migratepages);
isolated = 0;
} else
count_vm_numa_event(NUMA_PAGE_MIGRATE);
BUG_ON(!list_empty(&migratepages));
-out:
return isolated;
+
+out:
+ put_page(page);
+ return 0;
}
#endif /* CONFIG_NUMA_BALANCING */
#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+/*
+ * Migrates a THP to a given target node. page must be locked and is unlocked
+ * before returning.
+ */
int migrate_misplaced_transhuge_page(struct mm_struct *mm,
struct vm_area_struct *vma,
pmd_t *pmd, pmd_t entry,
@@ -1674,29 +1657,15 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
new_page = alloc_pages_node(node,
(GFP_TRANSHUGE | GFP_THISNODE) & ~__GFP_WAIT, HPAGE_PMD_ORDER);
- if (!new_page) {
- count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
- goto out_dropref;
- }
- page_xchg_last_nid(new_page, page_last_nid(page));
+ if (!new_page)
+ goto out_fail;
- isolated = numamigrate_isolate_page(pgdat, page);
+ page_nid_xchg_last(new_page, page_nid_last(page));
- /*
- * Failing to isolate or a GUP pin prevents migration. The expected
- * page count is 2. 1 for anonymous pages without a mapping and 1
- * for the callers pin. If the page was isolated, the page will
- * need to be put back on the LRU.
- */
- if (!isolated || page_count(page) != 2) {
- count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
+ isolated = numamigrate_isolate_page(pgdat, page);
+ if (!isolated) {
put_page(new_page);
- if (isolated) {
- putback_lru_page(page);
- isolated = 0;
- goto out;
- }
- goto out_keep_locked;
+ goto out_fail;
}
/* Prepare a page as a migration target */
@@ -1728,6 +1697,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
putback_lru_page(page);
count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
+ isolated = 0;
goto out;
}
@@ -1772,9 +1742,11 @@ out:
-HPAGE_PMD_NR);
return isolated;
+out_fail:
+ count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
out_dropref:
+ unlock_page(page);
put_page(page);
-out_keep_locked:
return 0;
}
#endif /* CONFIG_NUMA_BALANCING */