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-rw-r--r--include/linux/threads.h9
-rw-r--r--kernel/pid.c7
2 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/threads.h b/include/linux/threads.h
index 052b12b..383ab95 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 aebb30d..e9fd8c1 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);
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