1 files changed, 9 insertions, 0 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 376492ed08f4..e02f1aa66a1a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -27,6 +27,7 @@
 #include <linux/mount.h>
 #include <linux/mempolicy.h>
 #include <linux/rmap.h>
+#include <linux/ksm.h>
 #include <linux/mmu_notifier.h>
 #include <linux/perf_event.h>
 
@@ -2111,6 +2112,14 @@ void exit_mmap(struct mm_struct *mm)
         /* Use -1 here to ensure all VMAs in the mm are unmapped */
         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
         vm_unacct_memory(nr_accounted);
+
+        /*
+         * For KSM to handle OOM without deadlock when it's breaking COW in a
+         * likely victim of the OOM killer, we must serialize with ksm_exit()
+         * after freeing mm's pages but before freeing its page tables.
+         */
+        ksm_exit(mm, &tlb, end);
+
         free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
         tlb_finish_mmu(tlb, 0, end);