The previous time I've seen it was on 3.13.6, 3 weeks ago, I'm now on 3.14.1. Setting /proc/sys/vm/dirty_bytes to very high number (around 18446744073709550284) but still smaller than (uint64)-1 gets things running shortly/partially though. System is single-CPU, CONFIG_SMP=n, which might be important detail. On Sun, 27 April 2014 Bruno Prémont wrote: > On a 3.14 system (KVM virtual machine 512MB RAM, x86_64) I'm seeing > /proc/meminfo/Dirty getting extreemly large (u64 going "nevative"). > > Note, this is not the first time I'm seeing it. > > The system is not doing too much but has a rather small amount of > memory. > > MemTotal: 508512 kB > MemFree: 23076 kB > MemAvailable: 282092 kB > Buffers: 0 kB > Cached: 194548 kB > SwapCached: 1500 kB > Active: 168060 kB > Inactive: 203080 kB > Active(anon): 82300 kB > Inactive(anon): 95992 kB > Active(file): 85760 kB > Inactive(file): 107088 kB > Unevictable: 0 kB > Mlocked: 0 kB > SwapTotal: 524284 kB > SwapFree: 515820 kB > Dirty: 18446744073709550284 kB > Writeback: 4 kB > AnonPages: 175600 kB > Mapped: 28784 kB > Shmem: 1700 kB > Slab: 92244 kB > SReclaimable: 76812 kB > SUnreclaim: 15432 kB > KernelStack: 1128 kB > PageTables: 5588 kB > NFS_Unstable: 0 kB > Bounce: 0 kB > WritebackTmp: 0 kB > CommitLimit: 778540 kB > Committed_AS: 1036592 kB > VmallocTotal: 34359738367 kB > VmallocUsed: 4440 kB > VmallocChunk: 34359711231 kB > AnonHugePages: 0 kB > DirectMap4k: 10228 kB > DirectMap2M: 514048 kB > > Some tasks end up being stuck in balance_dirty_pages_ratelimited() > because of this. > > I have no idea what triggers Dirty to go mad but it happens. > It might be facilitated by some heavier IO (rsync of some data) > while rrdcached (rrdtool) is touching RRDs or writing its data log. > rrdcached is the one getting stuck in balance_dirty_pages_ratelimited(). > > Is there a way to get the system rolling again (making > dirty pages temporarily unlimited) or a way to determine why/when > Dirty goes negative and possibly get a hint on the trigger? > > Thanks, > Bruno -- 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/ . Don't email: <a href