1 files changed, 52 insertions, 1 deletions

diff --git a/src/port/pg_numa.c b/src/port/pg_numa.c
index 4b487a2a4e8..3368a43a338 100644
--- a/src/port/pg_numa.c
+++ b/src/port/pg_numa.c
@@ -16,6 +16,7 @@
 #include "c.h"
 #include <unistd.h>
 
+#include "miscadmin.h"
 #include "port/pg_numa.h"
 
 /*
@@ -29,6 +30,19 @@
 #include <numa.h>
 #include <numaif.h>
 
+/*
+ * numa_move_pages() chunk size, has to be <= 16 to work around a kernel bug
+ * in do_pages_stat() (chunked by DO_PAGES_STAT_CHUNK_NR). By using the same
+ * chunk size, we make it work even on unfixed kernels.
+ *
+ * 64-bit system are not affected by the bug, and so use much larger chunks.
+ */
+#if SIZEOF_SIZE_T == 4
+#define NUMA_QUERY_CHUNK_SIZE 16
+#else
+#define NUMA_QUERY_CHUNK_SIZE 1024
+#endif
+
 /* libnuma requires initialization as per numa(3) on Linux */
 int
 pg_numa_init(void)
@@ -42,11 +56,48 @@ pg_numa_init(void)
  * We use move_pages(2) syscall here - instead of get_mempolicy(2) - as the
  * first one allows us to batch and query about many memory pages in one single
  * giant system call that is way faster.
+ *
+ * We call numa_move_pages() for smaller chunks of the whole array. The first
+ * reason is to work around a kernel bug, but also to allow interrupting the
+ * query between the calls (for many pointers processing the whole array can
+ * take a lot of time).
  */
 int
 pg_numa_query_pages(int pid, unsigned long count, void **pages, int *status)
 {
-	return numa_move_pages(pid, count, pages, NULL, status, 0);
+	unsigned long next = 0;
+	int			ret = 0;
+
+	/*
+	 * Chunk pointers passed to numa_move_pages to NUMA_QUERY_CHUNK_SIZE
+	 * items, to work around a kernel bug in do_pages_stat().
+	 */
+	while (next < count)
+	{
+		unsigned long count_chunk = Min(count - next,
+										NUMA_QUERY_CHUNK_SIZE);
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Bail out if any of the chunks errors out (ret<0). We ignore (ret>0)
+		 * which is used to return number of nonmigrated pages, but we're not
+		 * migrating any pages here.
+		 */
+		ret = numa_move_pages(pid, count_chunk, &pages[next], NULL, &status[next], 0);
+		if (ret < 0)
+		{
+			/* plain error, return as is */
+			return ret;
+		}
+
+		next += count_chunk;
+	}
+
+	/* should have consumed the input array exactly */
+	Assert(next == count);
+
+	return 0;
 }
 
 int