Commit 16db3d3f authored by Heinrich Schuchardt's avatar Heinrich Schuchardt Committed by Linus Torvalds

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: default avatarHeinrich 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ac1b398d
...@@ -212,4 +212,7 @@ static inline void setup_sysctl_set(struct ctl_table_set *p, ...@@ -212,4 +212,7 @@ static inline void setup_sysctl_set(struct ctl_table_set *p,
#endif /* CONFIG_SYSCTL */ #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 */ #endif /* _LINUX_SYSCTL_H */
...@@ -74,6 +74,7 @@ ...@@ -74,6 +74,7 @@
#include <linux/uprobes.h> #include <linux/uprobes.h>
#include <linux/aio.h> #include <linux/aio.h>
#include <linux/compiler.h> #include <linux/compiler.h>
#include <linux/sysctl.h>
#include <asm/pgtable.h> #include <asm/pgtable.h>
#include <asm/pgalloc.h> #include <asm/pgalloc.h>
...@@ -266,7 +267,7 @@ void __init __weak arch_task_cache_init(void) { } ...@@ -266,7 +267,7 @@ void __init __weak arch_task_cache_init(void) { }
/* /*
* set_max_threads * set_max_threads
*/ */
static void set_max_threads(void) static void set_max_threads(unsigned int max_threads_suggested)
{ {
u64 threads; u64 threads;
...@@ -280,6 +281,9 @@ static void set_max_threads(void) ...@@ -280,6 +281,9 @@ static void set_max_threads(void)
threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE, threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
(u64) THREAD_SIZE * 8UL); (u64) THREAD_SIZE * 8UL);
if (threads > max_threads_suggested)
threads = max_threads_suggested;
max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS); max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
} }
...@@ -298,7 +302,7 @@ void __init fork_init(void) ...@@ -298,7 +302,7 @@ void __init fork_init(void)
/* do the arch specific task caches init */ /* do the arch specific task caches init */
arch_task_cache_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_cur = max_threads/2;
init_task.signal->rlim[RLIMIT_NPROC].rlim_max = 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) ...@@ -2020,3 +2024,26 @@ int unshare_files(struct files_struct **displaced)
task_unlock(task); task_unlock(task);
return 0; 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;
}
...@@ -93,11 +93,9 @@ ...@@ -93,11 +93,9 @@
#include <linux/nmi.h> #include <linux/nmi.h>
#endif #endif
#if defined(CONFIG_SYSCTL) #if defined(CONFIG_SYSCTL)
/* External variables not in a header file. */ /* External variables not in a header file. */
extern int max_threads;
extern int suid_dumpable; extern int suid_dumpable;
#ifdef CONFIG_COREDUMP #ifdef CONFIG_COREDUMP
extern int core_uses_pid; extern int core_uses_pid;
...@@ -710,10 +708,10 @@ static struct ctl_table kern_table[] = { ...@@ -710,10 +708,10 @@ static struct ctl_table kern_table[] = {
#endif #endif
{ {
.procname = "threads-max", .procname = "threads-max",
.data = &max_threads, .data = NULL,
.maxlen = sizeof(int), .maxlen = sizeof(int),
.mode = 0644, .mode = 0644,
.proc_handler = proc_dointvec, .proc_handler = sysctl_max_threads,
}, },
{ {
.procname = "random", .procname = "random",
......
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