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authorHeinrich Schuchardt <xypron.glpk@gmx.de>2015-04-16 12:47:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-17 09:04:07 -0400
commit16db3d3f1170fb0efca652c9378ce7c5f5cb4232 (patch)
treef85f846c4e8a4761449aeca34dbd1055bb693828 /kernel/fork.c
parentac1b398de1ef94aeee8ba87b0120763526572a6e (diff)
downloadlinux-sh-16db3d3f1170fb0efca652c9378ce7c5f5cb4232.tar.gz
kernel/sysctl.c: threads-max observe limits
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.glpk@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c31
1 files changed, 29 insertions, 2 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index c7f2e1a4187a..8807a129711b 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;
+
max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
}
@@ -298,7 +302,7 @@ 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;
@@ -2020,3 +2024,26 @@ 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;
+}