ipc,mqueue: remove limits for the amount of system-wide queues (f3713fd9) · Commits · 戴 / test

Commit ("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/+source/manpages/+bug/1155695 Instead of increasing this limit, revert it entirely and fallback to the original way of dealing queue limits -- where once a user's resource limit is reached, and all memory is used, new queues cannot be created. Signed-off-by:

Davidlohr Bueso <davidlohr@hp.com> Reported-by:

Madars Vitolins <m@silodev.com> Acked-by:

Doug Ledford <dledford@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: <stable@vger.kernel.org> [3.5+] Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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;
		}

Admin message