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Commit b74e6278 authored by Alex Thorlton's avatar Alex Thorlton Committed by Ingo Molnar
Browse files

sched: Fix KMALLOC_MAX_SIZE overflow during cpumask allocation 



When allocating space for load_balance_mask, in sched_init, when
CPUMASK_OFFSTACK is set, we've managed to spill over
KMALLOC_MAX_SIZE on our 6144 core machine.  The patch below
breaks up the allocations so that they don't overflow the max
alloc size.  It also allocates the masks on the the node from
which they'll most commonly be accessed, to minimize remote
accesses on NUMA machines.

Suggested-by: default avatarGeorge Beshers <gbeshers@sgi.com>
Signed-off-by: default avatarAlex Thorlton <athorlton@sgi.com>
Cc: George Beshers <gbeshers@sgi.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1418928270-148543-1-git-send-email-athorlton@sgi.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent aa39477b

kernel/sched/core.c

+5 −8
Original line number Diff line number Diff line
@@ -7112,9 +7112,6 @@ void __init sched_init(void) 
#endif

#ifdef CONFIG_RT_GROUP_SCHED

	alloc_size += 2 * nr_cpu_ids * sizeof(void **);

#endif

#ifdef CONFIG_CPUMASK_OFFSTACK

	alloc_size += num_possible_cpus() * cpumask_size();

#endif

	if (alloc_size) {

		ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
@@ -7135,13 +7132,13 @@ void __init sched_init(void) 
		ptr += nr_cpu_ids * sizeof(void **);



#endif /* CONFIG_RT_GROUP_SCHED */

	}

#ifdef CONFIG_CPUMASK_OFFSTACK

	for_each_possible_cpu(i) {

			per_cpu(load_balance_mask, i) = (void *)ptr;

			ptr += cpumask_size();

		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(

			cpumask_size(), GFP_KERNEL, cpu_to_node(i));

	}

#endif /* CONFIG_CPUMASK_OFFSTACK */

	}



	init_rt_bandwidth(&def_rt_bandwidth,

			global_rt_period(), global_rt_runtime());