[080/119] sched: Fix boot crash by zalloc()ing most of the cpu masks

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

commit 49557e620339cb134127b5bfbcfecc06b77d0232 upstream.

I got a boot crash when forcing cpumasks offstack on 32 bit,
because find_new_ilb() returned 3 on my UP system (nohz.cpu_mask
wasn't zeroed).

AFAICT the others need to be zeroed too: only
nohz.ilb_grp_nohz_mask is initialized before use.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
LKML-Reference: <200911022037.21282.rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 kernel/sched.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -9383,13 +9383,13 @@ void __init sched_init(void)
 	current->sched_class = &fair_sched_class;
 
 	/* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
-	alloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT);
+	zalloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT);
 #ifdef CONFIG_SMP
 #ifdef CONFIG_NO_HZ
-	alloc_cpumask_var(&nohz.cpu_mask, GFP_NOWAIT);
+	zalloc_cpumask_var(&nohz.cpu_mask, GFP_NOWAIT);
 	alloc_cpumask_var(&nohz.ilb_grp_nohz_mask, GFP_NOWAIT);
 #endif
-	alloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
+	zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
 #endif /* SMP */
 
 	perf_counter_init();


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