diff options
| author | Ingo Molnar <mingo@elte.hu> | 2009-09-04 11:49:25 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-04 11:52:52 +0200 |
| commit | d7ea17a76916e456fcc78e45142c66f7fb875e3d (patch) | |
| tree | be8422a0c60216991ccd98923fe13547738ab354 /kernel/sched.c | |
| parent | 18a3885fc1ffa92c2212ff0afdf033403d5b0fa0 (diff) | |
sched: Fix dynamic power-balancing crash
This crash:
[ 1774.088275] divide error: 0000 [#1] SMP
[ 1774.100355] CPU 13
[ 1774.102498] Modules linked in:
[ 1774.105631] Pid: 30881, comm: hackbench Not tainted 2.6.31-rc8-tip-01308-g484d664-dirty #1629 X8DTN
[ 1774.114807] RIP: 0010:[<ffffffff81041c38>] [<ffffffff81041c38>]
sched_balance_self+0x19b/0x2d4
Triggers because update_group_power() modifies the sd tree and does
temporary calculations there - not considering that other CPUs
could observe intermediate values, such as the zero initial value.
Calculate it in a temporary variable instead. (we need no memory
barrier as these are all statistical values anyway)
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20090904092742.GA11014@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index b53785346850..796baf731976 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3765,19 +3765,22 @@ static void update_group_power(struct sched_domain *sd, int cpu) { struct sched_domain *child = sd->child; struct sched_group *group, *sdg = sd->groups; + unsigned long power; if (!child) { update_cpu_power(sd, cpu); return; } - sdg->cpu_power = 0; + power = 0; group = child->groups; do { - sdg->cpu_power += group->cpu_power; + power += group->cpu_power; group = group->next; } while (group != child->groups); + + sdg->cpu_power = power; } /** |