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-rw-r--r--mm/compaction.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index fd988b7e5f2b..86375605faa9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2316,15 +2316,26 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
.page = NULL,
};
- current->capture_control = &capc;
+ /*
+ * Make sure the structs are really initialized before we expose the
+ * capture control, in case we are interrupted and the interrupt handler
+ * frees a page.
+ */
+ barrier();
+ WRITE_ONCE(current->capture_control, &capc);
ret = compact_zone(&cc, &capc);
VM_BUG_ON(!list_empty(&cc.freepages));
VM_BUG_ON(!list_empty(&cc.migratepages));
- *capture = capc.page;
- current->capture_control = NULL;
+ /*
+ * Make sure we hide capture control first before we read the captured
+ * page pointer, otherwise an interrupt could free and capture a page
+ * and we would leak it.
+ */
+ WRITE_ONCE(current->capture_control, NULL);
+ *capture = READ_ONCE(capc.page);
return ret;
}