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:[] [] 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) Got the same oops with the backport to -rt Signed-off-by: Dinakar Guniguntala Index: linux-2.6.31.4-rt14-lb1/kernel/sched.c =================================================================== --- linux-2.6.31.4-rt14-lb1.orig/kernel/sched.c 2009-10-21 10:49:03.000000000 -0400 +++ linux-2.6.31.4-rt14-lb1/kernel/sched.c 2009-10-22 01:48:41.000000000 -0400 @@ -3864,19 +3864,22 @@ { 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; } /** -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/