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authorHugh Dickins <hughd@google.com>2015-11-05 18:49:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-05 19:34:48 -0800
commit2def7424c9be0069831380823fdb5cf72103b919 (patch)
treef1d3f11cc8e1fd3c30d281f4fc47301a4174db66 /mm/migrate.c
parent14e0f9bcc95f1aef26a9f860cceda35faee79b34 (diff)
downloadop-kernel-dev-2def7424c9be0069831380823fdb5cf72103b919.zip
op-kernel-dev-2def7424c9be0069831380823fdb5cf72103b919.tar.gz
mm: page migration use the put_new_page whenever necessary
I don't know of any problem from the way it's used in our current tree, but there is one defect in page migration's custom put_new_page feature. An unused newpage is expected to be released with the put_new_page(), but there was one MIGRATEPAGE_SUCCESS (0) path which released it with putback_lru_page(): which can be very wrong for a custom pool. Fixed more easily by resetting put_new_page once it won't be needed, than by adding a further flag to modify the rc test. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
-rw-r--r--mm/migrate.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index d149cbb..2f2e223 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -938,10 +938,11 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
int force, enum migrate_mode mode,
enum migrate_reason reason)
{
- int rc = 0;
+ int rc = MIGRATEPAGE_SUCCESS;
int *result = NULL;
- struct page *newpage = get_new_page(page, private, &result);
+ struct page *newpage;
+ newpage = get_new_page(page, private, &result);
if (!newpage)
return -ENOMEM;
@@ -955,6 +956,8 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
goto out;
rc = __unmap_and_move(page, newpage, force, mode);
+ if (rc == MIGRATEPAGE_SUCCESS)
+ put_new_page = NULL;
out:
if (rc != -EAGAIN) {
@@ -981,7 +984,7 @@ out:
* it. Otherwise, putback_lru_page() will drop the reference grabbed
* during isolation.
*/
- if (rc != MIGRATEPAGE_SUCCESS && put_new_page) {
+ if (put_new_page) {
ClearPageSwapBacked(newpage);
put_new_page(newpage, private);
} else if (unlikely(__is_movable_balloon_page(newpage))) {
@@ -1022,7 +1025,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
struct page *hpage, int force,
enum migrate_mode mode)
{
- int rc = 0;
+ int rc = -EAGAIN;
int *result = NULL;
int page_was_mapped = 0;
struct page *new_hpage;
@@ -1044,8 +1047,6 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
if (!new_hpage)
return -ENOMEM;
- rc = -EAGAIN;
-
if (!trylock_page(hpage)) {
if (!force || mode != MIGRATE_SYNC)
goto out;
@@ -1070,8 +1071,10 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
if (anon_vma)
put_anon_vma(anon_vma);
- if (rc == MIGRATEPAGE_SUCCESS)
+ if (rc == MIGRATEPAGE_SUCCESS) {
hugetlb_cgroup_migrate(hpage, new_hpage);
+ put_new_page = NULL;
+ }
unlock_page(hpage);
out:
@@ -1083,7 +1086,7 @@ out:
* it. Otherwise, put_page() will drop the reference grabbed during
* isolation.
*/
- if (rc != MIGRATEPAGE_SUCCESS && put_new_page)
+ if (put_new_page)
put_new_page(new_hpage, private);
else
putback_active_hugepage(new_hpage);
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