2.6.23-stable review patch. If anyone has any objections, please let us know. ------------------ From: Chuck Ebbert No patch in mainline as this logic has been removed from 2.6.24 so it is not necessary. https://bugzilla.redhat.com/show_bug.cgi?id=340161 The problem code has been removed in 2.6.24. The below patch disables SCHED_FEAT_PRECISE_CPU_LOAD which causes the offending code to be skipped but does not prevent the user from enabling it. The divide-by-zero is here in kernel/sched.c: static void update_cpu_load(struct rq *this_rq) { u64 fair_delta64, exec_delta64, idle_delta64, sample_interval64, tmp64; unsigned long total_load = this_rq->ls.load.weight; unsigned long this_load = total_load; struct load_stat *ls = &this_rq->ls; int i, scale; this_rq->nr_load_updates++; if (unlikely(!(sysctl_sched_features & SCHED_FEAT_PRECISE_CPU_LOAD))) goto do_avg; /* Update delta_fair/delta_exec fields first */ update_curr_load(this_rq); fair_delta64 = ls->delta_fair + 1; ls->delta_fair = 0; exec_delta64 = ls->delta_exec + 1; ls->delta_exec = 0; sample_interval64 = this_rq->clock - ls->load_update_last; ls->load_update_last = this_rq->clock; if ((s64)sample_interval64 < (s64)TICK_NSEC) sample_interval64 = TICK_NSEC; if (exec_delta64 > sample_interval64) exec_delta64 = sample_interval64; idle_delta64 = sample_interval64 - exec_delta64; ======> tmp64 = div64_64(SCHED_LOAD_SCALE * exec_delta64, fair_delta64); tmp64 = div64_64(tmp64 * exec_delta64, sample_interval64); this_load = (unsigned long)tmp64; do_avg: /* Update our load: */ for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { unsigned long old_load, new_load; /* scale is effectively 1 << i now, and >> i divides by scale */ old_load = this_rq->cpu_load[i]; new_load = this_load; this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i; } } For stable only; the code has been removed in 2.6.24. Signed-off-by: Chuck Ebbert Acked-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched_fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -93,7 +93,7 @@ unsigned int sysctl_sched_features __rea SCHED_FEAT_FAIR_SLEEPERS *1 | SCHED_FEAT_SLEEPER_AVG *0 | SCHED_FEAT_SLEEPER_LOAD_AVG *1 | - SCHED_FEAT_PRECISE_CPU_LOAD *1 | + SCHED_FEAT_PRECISE_CPU_LOAD *0 | SCHED_FEAT_START_DEBIT *1 | SCHED_FEAT_SKIP_INITIAL *0; -- - 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/