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SubjectRe: [PATCH] sched: Fix isolcpus boot option
Date
On Mon, 30 Nov 2009 10:35:32 am Anton Blanchard wrote:
>
> We allocate and zero cpu_isolated_map after the isolcpus __setup option
> has run. This means cpu_isolated_map always ends up empty and if
> CPUMASK_OFFSTACK is enabled we write to a cpumask that hasn't been
> allocated.
>
> To keep the fix to a minimum this patch stores a pointer to the cmdline
> option and parses it after we allocate and zero the cpumask.

I introduced this regression in:

commit 49557e620339cb134127b5bfbcfecc06b77d0232
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon Nov 2 20:37:20 2009 +1030

sched: Fix boot crash by zalloc()ing most of the cpu masks

But this change made isolcpus= never work, CPUMASK_OFFSTACK or no.

Your patch works and is minimal.

Acked-by: Rusty Russell <rusty@rustcorp.com.au>

Thanks,
Rusty.

PS. This would have also worked:

diff --git a/kernel/sched.c b/kernel/sched.c
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8045,6 +8045,7 @@ static cpumask_var_t cpu_isolated_map;
/* Setup the mask of cpus configured for isolated domains */
static int __init isolated_cpu_setup(char *str)
{
+ alloc_bootmem_cpumask_var(&cpu_isolated_map);
cpulist_parse(str, cpu_isolated_map);
return 1;
}
@@ -9571,7 +9572,9 @@ void __init sched_init(void)
zalloc_cpumask_var(&nohz.cpu_mask, GFP_NOWAIT);
alloc_cpumask_var(&nohz.ilb_grp_nohz_mask, GFP_NOWAIT);
#endif
- zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
+ /* May be allocated at isolcpus cmdline parse time */
+ if (cpu_isolated_map == NULL)
+ zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
#endif /* SMP */

perf_event_init();




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