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Commit 6f7f02e7 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

cpusets: allow empty {cpus,mems}_allowed to be set for unpopulated cpuset 



You currently cannot remove all cpus or mems from cpus_allowed or
mems_allowed of a cpuset.  We now allow both if there are no attached
tasks.

Acked-by: default avatarPaul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: default avatarPaul Menage <menage@google.com>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0c28f287

kernel/cpuset.c

+30 −8
Original line number Diff line number Diff line
@@ -821,11 +821,22 @@ static int update_cpumask(struct cpuset *cs, char *buf) 
		return -EACCES;



	trialcs = *cs;



	/*

	 * We allow a cpuset's cpus_allowed to be empty; if it has attached

	 * tasks, we'll catch it later when we validate the change and return

	 * -ENOSPC.

	 */

	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {

		cpus_clear(trialcs.cpus_allowed);

	} else {

		retval = cpulist_parse(buf, trialcs.cpus_allowed);

		if (retval < 0)

			return retval;

	}

	cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);

	if (cpus_empty(trialcs.cpus_allowed))

	/* cpus_allowed cannot be empty for a cpuset with attached tasks. */

	if (atomic_read(&cs->count) && cpus_empty(trialcs.cpus_allowed))

		return -ENOSPC;

	retval = validate_change(cs, &trialcs);

	if (retval < 0)
@@ -918,16 +929,27 @@ static int update_nodemask(struct cpuset *cs, char *buf) 
		return -EACCES;



	trialcs = *cs;



	/*

	 * We allow a cpuset's mems_allowed to be empty; if it has attached

	 * tasks, we'll catch it later when we validate the change and return

	 * -ENOSPC.

	 */

	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {

		nodes_clear(trialcs.mems_allowed);

	} else {

		retval = nodelist_parse(buf, trialcs.mems_allowed);

		if (retval < 0)

			goto done;

	}

	nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);

	oldmem = cs->mems_allowed;

	if (nodes_equal(oldmem, trialcs.mems_allowed)) {

		retval = 0;		/* Too easy - nothing to do */

		goto done;

	}

	if (nodes_empty(trialcs.mems_allowed)) {

	/* mems_allowed cannot be empty for a cpuset with attached tasks. */

	if (atomic_read(&cs->count) && nodes_empty(trialcs.mems_allowed)) {

		retval = -ENOSPC;

		goto done;

	}