Hi, Tejun On Fri, Aug 30, 2013 at 10:52 AM, Anatol Pomozov <anatol.pomozov@xxxxxxxxx> wrote: > 'samples' is 64bit operant, but do_div() second parameter is 32. > do_div silently truncates high 32 bits and calculated result > is invalid. > > In case if low 32bit of 'samples' are zeros then do_div() produces > kernel crash. > > Signed-off-by: Anatol Pomozov <anatol.pomozov@xxxxxxxxx> > --- > block/cfq-iosched.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c > index d5bbdcf..c410752 100644 > --- a/block/cfq-iosched.c > +++ b/block/cfq-iosched.c > @@ -1803,7 +1803,7 @@ static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf, > > if (samples) { > v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum); > - do_div(v, samples); > + v = div64_u64(v, samples); > } > __blkg_prfill_u64(sf, pd, v); > return 0; what do you think about this patch? -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html