On Fri, 2013-10-18 at 21:26 +-0200, Helge Deller wrote: +AD4- On 10/17/2013 11:07 PM, Myklebust, Trond wrote: +AD4- +AD4- On Thu, 2013-10-17 at 22:42 +020-, Helge Deller wrote: +AD4- +AD4APg- I'm seeing a regression with current kernel git head when using NFS-mounts. +AD4- +AD4APg- Architecture in my case is parisc, although I don't think that this is relevant. +AD4- +AD4APg- At least kernel 3.10 (and I think 3.11) didn't showed that problem. +AD4- +AD4APg- +AD4- +AD4APg- The symtom is, that +ACI-top+ACI- shows high usage of either kswapd0 or kswapd1. +AD4- +AD4APg- Here is an output with kswapd1: +AD4- +AD4APg- PID USER PR NI VIRT RES SHR S +ACU-CPU +ACU-MEM TIME COMMAND +AD4- +AD4APg- 37 root 20 0 0 0 0 R 91.8 0.0 63:00.40 kswapd1 +AD4- +AD4APg- 28448 root 20 0 3252 1428 1060 R 15.3 0.0 0:00.09 top +AD4- +AD4APg- 1 root 20 0 2784 988 852 S 0.0 0.0 0:09.95 init +AD4- +AD4APg- +AD4- +AD4APg- This is what ps shows: +AD4- +AD4APg- lsXXXX:+AH4AIw- ps -ef +AHw- grep mount +AD4- +AD4APg- root 1181 1 0 14:51 ? 00:00:18 /usr/sbin/automount --pid-file /var/run/autofs.pid +AD4- +AD4APg- root 25331 1181 0 21:25 ? 00:00:00 /bin/mount -n -t nfs -s -o nolock,rw,hard,intr homes:/unixhome1 /net/home1 +AD4- +AD4APg- root 25332 25331 0 21:25 ? 00:00:00 /sbin/mount.nfs homes:/unixhome1 /net/home1 -s -n -o rw,nolock,hard,intr +AD4- +AD4APg- +AD4- +AD4APg- And using sysrq to show the blocked tasks I get in syslog: +AD4- +AD4APg- SysRq : Show Blocked State +AD4- +AD4APg- mount.nfs D 00000000401040c0 0 25332 25331 0x00000010 +AD4- +AD4APg- Backtrace: +AD4- +AD4APg- +AFsAPA-0000000040113a68+AD4AXQ- +AF8AXw-schedule+0x500/0x810- +AD4- +AD4APg- +AD4- +AD4APg- I know it's not a problem of the NFS server, since the same mount is still ok on other machines. +AD4- +AD4APg- The NFS directory was already mounted and in use when this mount happened again (called by cron-job). +AD4- +AD4APg- +AD4- +AD4APg- Any ideas? +AD4- +AD4- +AD4- +AD4- If the NFS directory is already mounted, then why is the automounter +AD4- +AD4- trying to mount it a second time? +AD4- +AD4- I was wrong in this. +AD4- The directory wasn't mounted yet (or at least it was unmounted in the meantime before the new +AD4- mount.nfs was called). +AD4- +AD4- I'm now not even sure, that the high kswapd is really triggered by the NFS problem, +AD4- because I now have another machine with the blocked NFS-mount, but without +AD4- the high kswapd usage. +AD4- +AD4- Nevertheless, the blocked nfs mount tasks really make me wonder. There is clearly +AD4- some kind of regression since it doesn't happen with older kernels. Have you ever reproduced it without the automounter? Also, could you please try a sysRQ-t the next time it happens, so that we can get a trace of where the mount program is hanging. Knowing that the mount is stuck in +ACIAXwBf-schedule()+ACI- is not really interesting unless we know from where that was called. -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust+AEA-netapp.com www.netapp.com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
