Users can change the maximum number of threads by writing to
/proc/sys/kernel/threads-max.
With the patch the value entered is checked against the same
limits that apply when fork_init is called.
Signed-off-by: Heinrich Schuchardt <xypron.g...@gmx.de>
---
include/linux/sysctl.h | 3 +++
kernel/fork.c | 31 +++++++++++++++++++++++++++++--
kernel/sysctl.c | 6 ++----
3 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index b7361f8..795d5fe 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -212,4 +212,7 @@ static inline void setup_sysctl_set(struct ctl_table_set *p,
#endif /* CONFIG_SYSCTL */
+int sysctl_max_threads(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
+
#endif /* _LINUX_SYSCTL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 69ff08f..3a359fda 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -74,6 +74,7 @@
#include <linux/uprobes.h>
#include <linux/aio.h>
#include <linux/compiler.h>
+#include <linux/sysctl.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -266,7 +267,7 @@ void __init __weak arch_task_cache_init(void) { }
/*
* set_max_threads
*/
-static void set_max_threads(void)
+static void set_max_threads(unsigned int max_threads_suggested)
{
u64 threads;
@@ -280,6 +281,9 @@ static void set_max_threads(void)
threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
(u64) THREAD_SIZE * 8UL);
+ if (threads > max_threads_suggested)
+ threads = max_threads_suggested;
+
if (threads > MAX_THREADS)
threads = MAX_THREADS;
@@ -304,7 +308,7 @@ void __init fork_init(void)
/* do the arch specific task caches init */
arch_task_cache_init();
- set_max_threads();
+ set_max_threads(MAX_THREADS);
init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
@@ -2024,3 +2028,26 @@ int unshare_files(struct files_struct **displaced)
task_unlock(task);
return 0;
}
+
+int sysctl_max_threads(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table t;
+ int ret;
+ int threads = max_threads;
+ int min = MIN_THREADS;
+ int max = MAX_THREADS;
+
+ t = *table;
+ t.data = &threads;
+ t.extra1 = &min;
+ t.extra2 = &max;
+
+ ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
+ if (ret || !write)
+ return ret;
+
+ set_max_threads(threads);
+
+ return 0;
+}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index f57c5ae..80920a6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -92,11 +92,9 @@
#include <linux/nmi.h>
#endif
-
#if defined(CONFIG_SYSCTL)
/* External variables not in a header file. */
-extern int max_threads;
extern int suid_dumpable;
#ifdef CONFIG_COREDUMP
extern int core_uses_pid;
@@ -702,10 +700,10 @@ static struct ctl_table kern_table[] = {
#endif
{
.procname = "threads-max",
- .data = &max_threads,
+ .data = NULL,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = sysctl_max_threads,
},
{
.procname = "random",
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
