[tip:sched/core] sched: Fix isolcpus boot option

[tip-bot for Rusty Russell]

Commit-ID:  bdddd2963c0264c56f18043f6fa829d3c1d3d1c0
Gitweb:     http://git.kernel.org/tip/bdddd2963c0264c56f18043f6fa829d3c1d3d1c0
Author:     Rusty Russell <rusty@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 2 Dec 2009 14:09:16 +1030
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 2 Dec 2009 10:27:16 +0100

sched: Fix isolcpus boot option

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 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 1031cae..4883fee 100644
--- 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;
 }
@@ -9609,7 +9610,9 @@ 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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