Hello, On Fri, Jul 13, 2012 at 10:08:00AM +0800, Fengguang Wu wrote: > [ 0.165669] Performance Events: unsupported Netburst CPU model 6 no PMU driver, software events only. > [ 0.167001] XXX cpu=0 gcwq=ffff88000dc0cfc0 base=ffff88000dc11e80 > [ 0.167989] XXX cpu=0 nr_running=0 @ ffff88000dc11e80 > [ 0.168988] XXX cpu=0 nr_running=0 @ ffff88000dc11e88 > [ 0.169988] XXX cpu=1 gcwq=ffff88000dd0cfc0 base=ffff88000dd11e80 > [ 0.170988] XXX cpu=1 nr_running=0 @ ffff88000dd11e80 > [ 0.171987] XXX cpu=1 nr_running=0 @ ffff88000dd11e88 > [ 0.172988] XXX cpu=8 nr_running=0 @ ffffffff81d7c430 > [ 0.173987] XXX cpu=8 nr_running=12 @ ffffffff81d7c438 Heh, I found it. get_pool_nr_running() stores the nr_running array to use in a local pointer to array and then returns pointer to the specific element from there depending on the priority. atomic_t (*nr_running)[NR_WORKER_POOLS]; /* set @nr_running to the array to use */ return nr_running[worker_pool_pri(pool)]; The [] operator in the return statement is indexing to the arrays instead of the array elements, so if the index is 1, the above statement offsets nr_running by sizeof(atomic_t [NR_WORKER_POOLS]) instead of sizeof(atomic_t). This should have been &(*nr_running)[worker_pool_pri(pool)] instead. So, highpri ends up dereferencing out-of-bounds and depending on variable layout, it may see garbage value from the beginning (what you were seeing) or get interfered afterwards (what Tony was seeing). This also explains why I didn't see it and Tony can no longer reproduce it after debug patch. Will post updated patches. Thank you. -- tejun _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
