LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Heinrich Schuchardt <xypron.glpk@gmx.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Aaron Tomlin <atomlin@redhat.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Davidlohr Bueso <dave@stgolabs.net>,
	David Rientjes <rientjes@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Fabian Frederick <fabf@skynet.be>,
	Guenter Roeck <linux@roeck-us.net>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
	Jens Axboe <axboe@fb.com>, Joe Perches <joe@perches.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Michael Marineau <mike@marineau.org>,
	Oleg Nesterov <oleg@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Prarit Bhargava <prarit@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vladimir Davydov <vdavydov@parallels.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	Heinrich Schuchardt <xypron.glpk@gmx.de>
Subject: [PATCH 3/4 v6] kernel/sysctl.c: threads-max observe limits
Date: Sun, 15 Mar 2015 17:13:37 +0100	[thread overview]
Message-ID: <1426436018-5159-4-git-send-email-xypron.glpk@gmx.de> (raw)
In-Reply-To: <1426436018-5159-1-git-send-email-xypron.glpk@gmx.de>

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>
---
 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


  parent reply	other threads:[~2015-03-15 16:16 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-15 16:13 [PATCH 0/4 v6] max_threadx handling Heinrich Schuchardt
2015-03-15 16:13 ` [PATCH 1/4 v6] kernel/fork.c: new function for max_threads Heinrich Schuchardt
2015-03-15 16:13 ` [PATCH 2/4 v6] kernel/fork.c: avoid division by zero Heinrich Schuchardt
2015-03-16  7:41   ` Ingo Molnar
2015-03-17 19:19     ` Heinrich Schuchardt
2015-03-18 16:49       ` Ingo Molnar
2015-03-18 17:06         ` Oleg Nesterov
2015-03-25 12:25           ` Ingo Molnar
2015-03-15 16:13 ` Heinrich Schuchardt [this message]
2015-03-15 16:13 ` [PATCH 4/4 v6] Doc/sysctl/kernel.txt: document threads-max Heinrich Schuchardt
2015-03-15 16:30   ` Guenter Roeck
2015-03-25 18:59 ` [PATCH 0/4 v6] max_threadx handling Heinrich Schuchardt

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1426436018-5159-4-git-send-email-xypron.glpk@gmx.de \
    --to=xypron.glpk@gmx.de \
    --cc=akpm@linux-foundation.org \
    --cc=atomlin@redhat.com \
    --cc=axboe@fb.com \
    --cc=corbet@lwn.net \
    --cc=dave@stgolabs.net \
    --cc=davem@davemloft.net \
    --cc=fabf@skynet.be \
    --cc=hannes@cmpxchg.org \
    --cc=hpa@zytor.com \
    --cc=joe@perches.com \
    --cc=keescook@chromium.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@roeck-us.net \
    --cc=luto@amacapital.net \
    --cc=mike@marineau.org \
    --cc=mingo@kernel.org \
    --cc=oleg@redhat.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=prarit@redhat.com \
    --cc=riel@redhat.com \
    --cc=rientjes@google.com \
    --cc=rostedt@goodmis.org \
    --cc=rusty@rustcorp.com.au \
    --cc=tglx@linutronix.de \
    --cc=vdavydov@parallels.com \
    --subject='Re: [PATCH 3/4 v6] kernel/sysctl.c: threads-max observe limits' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).