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Commit 8f37961c authored by Tim Chen's avatar Tim Chen Committed by Ingo Molnar
Browse files

sched/core, x86/topology: Fix NUMA in package topology bug 



Current code can call set_cpu_sibling_map() and invoke sched_set_topology()
more than once (e.g. on CPU hot plug).  When this happens after
sched_init_smp() has been called, we lose the NUMA topology extension to
sched_domain_topology in sched_init_numa().  This results in incorrect
topology when the sched domain is rebuilt.

This patch fixes the bug and issues warning if we call sched_set_topology()
after sched_init_smp().

Signed-off-by: default avatarTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@suse.de
Cc: jolsa@redhat.com
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1474485552-141429-2-git-send-email-srinivas.pandruvada@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 536e0e81

arch/x86/kernel/smpboot.c

+30 −16
Original line number Diff line number Diff line
@@ -471,7 +471,7 @@ static bool match_die(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o) 
	return false;

}



static struct sched_domain_topology_level numa_inside_package_topology[] = {

static struct sched_domain_topology_level x86_numa_in_package_topology[] = {

#ifdef CONFIG_SCHED_SMT

	{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },

#endif
@@ -480,22 +480,23 @@ static struct sched_domain_topology_level numa_inside_package_topology[] = { 
#endif

	{ NULL, },

};



static struct sched_domain_topology_level x86_topology[] = {

#ifdef CONFIG_SCHED_SMT

	{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },

#endif

#ifdef CONFIG_SCHED_MC

	{ cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },

#endif

	{ cpu_cpu_mask, SD_INIT_NAME(DIE) },

	{ NULL, },

};



/*

 * set_sched_topology() sets the topology internal to a CPU.  The

 * NUMA topologies are layered on top of it to build the full

 * system topology.

 *

 * If NUMA nodes are observed to occur within a CPU package, this

 * function should be called.  It forces the sched domain code to

 * only use the SMT level for the CPU portion of the topology.

 * This essentially falls back to relying on NUMA information

 * from the SRAT table to describe the entire system topology

 * (except for hyperthreads).

 */

static void primarily_use_numa_for_topology(void)

{

	set_sched_topology(numa_inside_package_topology);

}

 * Set if a package/die has multiple NUMA nodes inside.

 * AMD Magny-Cours and Intel Cluster-on-Die have this.

 */

static bool x86_has_numa_in_package;



void set_cpu_sibling_map(int cpu)

{
@@ -558,7 +559,7 @@ void set_cpu_sibling_map(int cpu) 
				c->booted_cores = cpu_data(i).booted_cores;

		}

		if (match_die(c, o) && !topology_same_node(c, o))

			primarily_use_numa_for_topology();

			x86_has_numa_in_package = true;

	}



	threads = cpumask_weight(topology_sibling_cpumask(cpu));
@@ -1304,6 +1305,16 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) 
		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);

		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);

	}



	/*

	 * Set 'default' x86 topology, this matches default_topology() in that

	 * it has NUMA nodes as a topology level. See also

	 * native_smp_cpus_done().

	 *

	 * Must be done before set_cpus_sibling_map() is ran.

	 */

	set_sched_topology(x86_topology);



	set_cpu_sibling_map(0);



	switch (smp_sanity_check(max_cpus)) {
@@ -1370,6 +1381,9 @@ void __init native_smp_cpus_done(unsigned int max_cpus) 
{

	pr_debug("Boot done\n");



	if (x86_has_numa_in_package)

		set_sched_topology(x86_numa_in_package_topology);



	nmi_selftest();

	impress_friends();

	setup_ioapic_dest();

kernel/sched/core.c

+3 −0
Original line number Diff line number Diff line
@@ -6552,6 +6552,9 @@ static struct sched_domain_topology_level *sched_domain_topology = 


void set_sched_topology(struct sched_domain_topology_level *tl)

{

	if (WARN_ON_ONCE(sched_smp_initialized))

		return;



	sched_domain_topology = tl;

}