mm/khugepaged: fix the xas_create_range() error path
collapse_shmem()'s xas_nomem() is very unlikely to fail, but it is
rightly given a failure path, so move the whole xas_create_range() block
up before __SetPageLocked(new_page): so that it does not need to
remember to unlock_page(new_page).
Add the missing mem_cgroup_cancel_charge(), and set (currently unused)
result to SCAN_FAIL rather than SCAN_SUCCEED.
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261531200.2275@eggly.anvils
Fixes: 77da9389b9d5 ("mm: Convert collapse_shmem to XArray")
Signed-off-by: Hugh Dickins <hughd@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 2c5fe4f..8e2ff195 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1329,6 +1329,20 @@
goto out;
}
+ /* This will be less messy when we use multi-index entries */
+ do {
+ xas_lock_irq(&xas);
+ xas_create_range(&xas);
+ if (!xas_error(&xas))
+ break;
+ xas_unlock_irq(&xas);
+ if (!xas_nomem(&xas, GFP_KERNEL)) {
+ mem_cgroup_cancel_charge(new_page, memcg, true);
+ result = SCAN_FAIL;
+ goto out;
+ }
+ } while (1);
+
__SetPageLocked(new_page);
__SetPageSwapBacked(new_page);
new_page->index = start;
@@ -1340,17 +1354,6 @@
* be able to map it or use it in another way until we unlock it.
*/
- /* This will be less messy when we use multi-index entries */
- do {
- xas_lock_irq(&xas);
- xas_create_range(&xas);
- if (!xas_error(&xas))
- break;
- xas_unlock_irq(&xas);
- if (!xas_nomem(&xas, GFP_KERNEL))
- goto out;
- } while (1);
-
xas_set(&xas, start);
for (index = start; index < end; index++) {
struct page *page = xas_next(&xas);
