Commit 8295c699 authored Dec 02, 2015 by Xunlei Pang Committed by Ingo Molnar Dec 04, 2015

sched/core: Clear the root_domain cpumasks in init_rootdomain()



root_domain::rto_mask allocated through alloc_cpumask_var()
contains garbage data, this may cause problems. For instance,
When doing pull_rt_task(), it may do useless iterations if
rto_mask retains some extra garbage bits. Worse still, this
violates the isolated domain rule for clustered scheduling
using cpuset, because the tasks(with all the cpus allowed)
belongs to one root domain can be pulled away into another
root domain.

The patch cleans the garbage by using zalloc_cpumask_var()
instead of alloc_cpumask_var() for root_domain::rto_mask
allocation, thereby addressing the issues.

Do the same thing for root_domain's other cpumask memembers:
dlo_mask, span, and online.

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1449057179-29321-1-git-send-email-xlpang@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 119d6f6a

kernel/sched/core.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -5846,13 +5846,13 @@ static int init_rootdomain(struct root_domain *rd)
		{
		memset(rd, 0, sizeof(*rd));

		if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
		if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
		goto out;
		if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
		if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
		goto free_span;
		if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
		if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
		goto free_online;
		if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
		if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
		goto free_dlo_mask;

		init_dl_bw(&rd->dl_bw);

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