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: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Paul Menage <menage@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -821,11 +821,22 @@ static int update_cpumask(struct cpuset *cs, char *buf)
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return -EACCES;
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trialcs = *cs;
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retval = cpulist_parse(buf, trialcs.cpus_allowed);
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if (retval < 0)
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return retval;
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/*
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* We allow a cpuset's cpus_allowed to be empty; if it has attached
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* tasks, we'll catch it later when we validate the change and return
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* -ENOSPC.
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*/
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if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
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cpus_clear(trialcs.cpus_allowed);
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} else {
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retval = cpulist_parse(buf, trialcs.cpus_allowed);
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if (retval < 0)
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return retval;
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}
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cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
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if (cpus_empty(trialcs.cpus_allowed))
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/* cpus_allowed cannot be empty for a cpuset with attached tasks. */
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if (atomic_read(&cs->count) && cpus_empty(trialcs.cpus_allowed))
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return -ENOSPC;
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retval = validate_change(cs, &trialcs);
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if (retval < 0)
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@ -918,16 +929,27 @@ static int update_nodemask(struct cpuset *cs, char *buf)
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return -EACCES;
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trialcs = *cs;
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retval = nodelist_parse(buf, trialcs.mems_allowed);
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if (retval < 0)
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goto done;
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/*
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* We allow a cpuset's mems_allowed to be empty; if it has attached
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* tasks, we'll catch it later when we validate the change and return
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* -ENOSPC.
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*/
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if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
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nodes_clear(trialcs.mems_allowed);
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} else {
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retval = nodelist_parse(buf, trialcs.mems_allowed);
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if (retval < 0)
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goto done;
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}
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nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
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oldmem = cs->mems_allowed;
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if (nodes_equal(oldmem, trialcs.mems_allowed)) {
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retval = 0; /* Too easy - nothing to do */
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goto done;
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}
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if (nodes_empty(trialcs.mems_allowed)) {
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/* mems_allowed cannot be empty for a cpuset with attached tasks. */
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if (atomic_read(&cs->count) && nodes_empty(trialcs.mems_allowed)) {
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retval = -ENOSPC;
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goto done;
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}
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