Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f3713fd9 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

ipc,mqueue: remove limits for the amount of system-wide queues 

Commit 93e6f119 ("ipc/mqueue: cleanup definition names and
locations") added global hardcoded limits to the amount of message
queues that can be created.  While these limits are per-namespace,
reality is that it ends up breaking userspace applications.
Historically users have, at least in theory, been able to create up to
INT_MAX queues, and limiting it to just 1024 is way too low and dramatic
for some workloads and use cases.  For instance, Madars reports:

 "This update imposes bad limits on our multi-process application.  As
  our app uses approaches that each process opens its own set of queues
  (usually something about 3-5 queues per process).  In some scenarios
  we might run up to 3000 processes or more (which of-course for linux
  is not a problem).  Thus we might need up to 9000 queues or more.  All
  processes run under one user."

Other affected users can be found in launchpad bug #1155695:
  https://bugs.launchpad.net/ubuntu/+...
parent 08088cb9

include/linux/ipc_namespace.h

+0 −2
Original line number Diff line number Diff line
@@ -118,9 +118,7 @@ extern int mq_init_ns(struct ipc_namespace *ns); 
 *     the new maximum will handle anyone else.  I may have to revisit this

 *     in the future.

 */

#define MIN_QUEUESMAX			1

#define DFLT_QUEUESMAX		      256

#define HARD_QUEUESMAX		     1024

#define MIN_MSGMAX			1

#define DFLT_MSG		       10U

#define DFLT_MSGMAX		       10

ipc/mq_sysctl.c

+12 −6
Original line number Diff line number Diff line
@@ -22,6 +22,16 @@ static void *get_mq(ctl_table *table) 
	return which;

}



static int proc_mq_dointvec(ctl_table *table, int write,

			    void __user *buffer, size_t *lenp, loff_t *ppos)

{

	struct ctl_table mq_table;

	memcpy(&mq_table, table, sizeof(mq_table));

	mq_table.data = get_mq(table);



	return proc_dointvec(&mq_table, write, buffer, lenp, ppos);

}



static int proc_mq_dointvec_minmax(ctl_table *table, int write,

	void __user *buffer, size_t *lenp, loff_t *ppos)

{
@@ -33,12 +43,10 @@ static int proc_mq_dointvec_minmax(ctl_table *table, int write, 
					lenp, ppos);

}

#else

#define proc_mq_dointvec NULL

#define proc_mq_dointvec_minmax NULL

#endif



static int msg_queues_limit_min = MIN_QUEUESMAX;

static int msg_queues_limit_max = HARD_QUEUESMAX;



static int msg_max_limit_min = MIN_MSGMAX;

static int msg_max_limit_max = HARD_MSGMAX;
@@ -51,9 +59,7 @@ static ctl_table mq_sysctls[] = { 
		.data		= &init_ipc_ns.mq_queues_max,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_mq_dointvec_minmax,

		.extra1		= &msg_queues_limit_min,

		.extra2		= &msg_queues_limit_max,

		.proc_handler	= proc_mq_dointvec,

	},

	{

		.procname	= "msg_max",

ipc/mqueue.c

+3 −3
Original line number Diff line number Diff line
@@ -433,9 +433,9 @@ static int mqueue_create(struct inode *dir, struct dentry *dentry, 
		error = -EACCES;

		goto out_unlock;

	}

	if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||

	    (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&

	     !capable(CAP_SYS_RESOURCE))) {



	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&

	    !capable(CAP_SYS_RESOURCE)) {

		error = -ENOSPC;

		goto out_unlock;

	}