[28/98] sched: Fix isolcpus boot option

From: Greg KH
Date: Tue Jan 26 2010 - 19:02:08 EST

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


From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

commit bdddd2963c0264c56f18043f6fa829d3c1d3d1c0 upstream.

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.

I introduced this regression in 49557e620339cb13 (sched: Fix
boot crash by zalloc()ing most of the cpu masks).

Use the bootmem allocator if they set isolcpus=, otherwise
allocate and zero like normal.

Reported-by: Anton Blanchard <anton@xxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: peterz@xxxxxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
LKML-Reference: <200912021409.17013.rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Tested-by: Anton Blanchard <anton@xxxxxxxxx>

kernel/sched.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8061,6 +8061,7 @@ 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;
@@ -9591,7 +9592,9 @@ void __init sched_init(void)
zalloc_cpumask_var(&nohz.cpu_mask, GFP_NOWAIT);
alloc_cpumask_var(&nohz.ilb_grp_nohz_mask, GFP_NOWAIT);
- 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 */


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