On Fri, Jun 24, 2011 at 6:27 PM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > Hi Andrew, > > Sorry but right now I don't have a time to dive into this. > But it seems to be similar to the problem Mel is looking at. > Cced him. > > Even, Pádraig Brady seem to have a reproducible scenario. > I will look when I have a time. > I hope I will be back sooner or later. > > > On Fri, Jun 24, 2011 at 3:22 PM, Andrew Lutomirski <luto@xxxxxxx> wrote: >> I'm back :-/ >> >> I just triggered the kswapd bug on 2.6.39.1, which has the >> cond_resched in shrink_slab. This time my system's still usable (I'm >> tying this email on it), but kswapd0 is taking 100% cpu. It *does* >> schedule (tested by setting its affinity the same as another CPU hog >> and confirming that each one gets 50%). >> >> It appears to be calling i915_gem_inactive_shrink in a loop. I have >> probes on entry and return of i915_gem_inactive_shrink and on return >> of shrink_slab. I see: >> >> kswapd0 47 [000] 59599.956573: mm_vmscan_kswapd_wake: nid=0 order=0 >> kswapd0 47 [000] 59599.956575: shrink_zone: >> (ffffffff810c848c) priority=12 zone=ffff8801005fe000 >> kswapd0 47 [000] 59599.956576: shrink_zone_return: >> (ffffffff810c848c <- ffffffff810c96c6) arg1=0 >> kswapd0 47 [000] 59599.956578: i915_gem_inactive_shrink: >> (ffffffffa0081e48) gfp_mask=d0 nr_to_scan=0 >> kswapd0 47 [000] 59599.956589: shrink_return: >> (ffffffffa0081e48 <- ffffffff810c6a62) arg1=320 >> kswapd0 47 [000] 59599.956589: shrink_slab_return: >> (ffffffff810c69f5 <- ffffffff810c96ec) arg1=0 >> kswapd0 47 [000] 59599.956592: i915_gem_inactive_shrink: >> (ffffffffa0081e48) gfp_mask=d0 nr_to_scan=0 >> kswapd0 47 [000] 59599.956602: shrink_return: >> (ffffffffa0081e48 <- ffffffff810c6a62) arg1=320 >> kswapd0 47 [000] 59599.956603: shrink_slab_return: >> (ffffffff810c69f5 <- ffffffff810c96ec) arg1=0 >> kswapd0 47 [000] 59599.956605: shrink_zone: >> (ffffffff810c848c) priority=12 zone=ffff8801005fee00 >> kswapd0 47 [000] 59599.956606: shrink_zone_return: >> (ffffffff810c848c <- ffffffff810c96c6) arg1=0 >> kswapd0 47 [000] 59599.956608: i915_gem_inactive_shrink: >> (ffffffffa0081e48) gfp_mask=d0 nr_to_scan=0 >> kswapd0 47 [000] 59599.956609: shrink_return: >> (ffffffffa0081e48 <- ffffffff810c6a62) arg1=0 >> kswapd0 47 [000] 59599.956610: shrink_slab_return: >> (ffffffff810c69f5 <- ffffffff810c96ec) arg1=0 >> kswapd0 47 [000] 59599.956611: mm_vmscan_kswapd_wake: nid=0 order=0 >> kswapd0 47 [000] 59599.956612: shrink_zone: >> (ffffffff810c848c) priority=12 zone=ffff8801005fe000 >> kswapd0 47 [000] 59599.956614: shrink_zone_return: >> (ffffffff810c848c <- ffffffff810c96c6) arg1=0 >> kswapd0 47 [000] 59599.956616: i915_gem_inactive_shrink: >> (ffffffffa0081e48) gfp_mask=d0 nr_to_scan=0 >> kswapd0 47 [000] 59599.956617: shrink_return: >> (ffffffffa0081e48 <- ffffffff810c6a62) arg1=0 >> kswapd0 47 [000] 59599.956618: shrink_slab_return: >> (ffffffff810c69f5 <- ffffffff810c96ec) arg1=0 >> kswapd0 47 [000] 59599.956620: i915_gem_inactive_shrink: >> (ffffffffa0081e48) gfp_mask=d0 nr_to_scan=0 >> kswapd0 47 [000] 59599.956621: shrink_return: >> (ffffffffa0081e48 <- ffffffff810c6a62) arg1=0 >> kswapd0 47 [000] 59599.956621: shrink_slab_return: >> (ffffffff810c69f5 <- ffffffff810c96ec) arg1=0 >> kswapd0 47 [000] 59599.956623: shrink_zone: >> (ffffffff810c848c) priority=12 zone=ffff8801005fee00 >> kswapd0 47 [000] 59599.956624: shrink_zone_return: >> (ffffffff810c848c <- ffffffff810c96c6) arg1=0 >> kswapd0 47 [000] 59599.956626: i915_gem_inactive_shrink: >> (ffffffffa0081e48) gfp_mask=d0 nr_to_scan=0 >> kswapd0 47 [000] 59599.956627: shrink_return: >> (ffffffffa0081e48 <- ffffffff810c6a62) arg1=0 >> kswapd0 47 [000] 59599.956628: shrink_slab_return: >> (ffffffff810c69f5 <- ffffffff810c96ec) arg1=0 >> kswapd0 47 [000] 59599.956629: mm_vmscan_kswapd_wake: nid=0 order=0 >> >> The command was: >> >> perf record -g -aR -p 47 -e probe:i915_gem_inactive_shrink -e >> probe:shrink_return -e probe:shrink_slab_return -e probe:shrink_zone >> -e probe:shrink_zone_return -e probe:kswapd_try_to_sleep -e >> vmscan:mm_vmscan_kswapd_sleep -e vmscan:mm_vmscan_kswapd_wake -e >> vmscan:mm_vmscan_wakeup_kswapd -e vmscan:mm_vmscan_lru_shrink_inactive >> -e probe:wakeup_kswapd; perf script >> >> (shrink_return is i915_gem_inactive_shrink's return. sorry, badly named.) >> >> It looks like something kswapd_try_to_sleep is not getting called. >> >> I do not know how to reproduce this, but I'll leave it running overnight. If the problem happen again, could you probe wakeup_kswapd, too? I think it can help us. Thanks. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href