On 10/17/2013 11:07 PM, Myklebust, Trond wrote: > On Thu, 2013-10-17 at 22:42 +0200, Helge Deller wrote: >> I'm seeing a regression with current kernel git head when using NFS-mounts. >> Architecture in my case is parisc, although I don't think that this is relevant. >> At least kernel 3.10 (and I think 3.11) didn't showed that problem. >> >> The symtom is, that "top" shows high usage of either kswapd0 or kswapd1. >> Here is an output with kswapd1: >> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND >> 37 root 20 0 0 0 0 R 91.8 0.0 63:00.40 kswapd1 >> 28448 root 20 0 3252 1428 1060 R 15.3 0.0 0:00.09 top >> 1 root 20 0 2784 988 852 S 0.0 0.0 0:09.95 init >> >> This is what ps shows: >> lsXXXX:~# ps -ef | grep mount >> root 1181 1 0 14:51 ? 00:00:18 /usr/sbin/automount --pid-file /var/run/autofs.pid >> root 25331 1181 0 21:25 ? 00:00:00 /bin/mount -n -t nfs -s -o nolock,rw,hard,intr homes:/unixhome1 /net/home1 >> root 25332 25331 0 21:25 ? 00:00:00 /sbin/mount.nfs homes:/unixhome1 /net/home1 -s -n -o rw,nolock,hard,intr >> >> And using sysrq to show the blocked tasks I get in syslog: >> SysRq : Show Blocked State >> mount.nfs D 00000000401040c0 0 25332 25331 0x00000010 >> Backtrace: >> [<0000000040113a68>] __schedule+0x500/0x810 >> >> I know it's not a problem of the NFS server, since the same mount is still ok on other machines. >> The NFS directory was already mounted and in use when this mount happened again (called by cron-job). >> >> Any ideas? > > If the NFS directory is already mounted, then why is the automounter > trying to mount it a second time? I was wrong in this. The directory wasn't mounted yet (or at least it was unmounted in the meantime before the new mount.nfs was called). I'm now not even sure, that the high kswapd is really triggered by the NFS problem, because I now have another machine with the blocked NFS-mount, but without the high kswapd usage. Nevertheless, the blocked nfs mount tasks really make me wonder. There is clearly some kind of regression since it doesn't happen with older kernels. Helge -- 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
