2 files changed, 16 insertions, 0 deletions

diff --git a/include/linux/threads.h b/include/linux/threads.h
index 052b12bec8bd..383ab9592bec 100644
--- a/include/linux/threads.h
+++ b/include/linux/threads.h
@@ -33,4 +33,13 @@
 #define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
         (sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
 
+/*
+ * Define a minimum number of pids per cpu.  Heuristically based
+ * on original pid max of 32k for 32 cpus.  Also, increase the
+ * minimum settable value for pid_max on the running system based
+ * on similar defaults.  See kernel/pid.c:pidmap_init() for details.
+ */
+#define PIDS_PER_CPU_DEFAULT    1024
+#define PIDS_PER_CPU_MIN        8
+
 #endif
diff --git a/kernel/pid.c b/kernel/pid.c
index aebb30d9c233..e9fd8c132d26 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -513,6 +513,13 @@ void __init pidhash_init(void)
 
 void __init pidmap_init(void)
 {
+        /* bump default and minimum pid_max based on number of cpus */
+        pid_max = min(pid_max_max, max_t(int, pid_max,
+                                PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
+        pid_max_min = max_t(int, pid_max_min,
+                                PIDS_PER_CPU_MIN * num_possible_cpus());
+        pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
+
         init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
         /* Reserve PID 0. We never call free_pidmap(0) */
         set_bit(0, init_pid_ns.pidmap[0].page);