2009/6/29 Kostik Belousov <kostik...@gmail.com>: > On Mon, Jun 29, 2009 at 05:18:03PM +0400, pluknet wrote: >> 2009/6/29 Attilio Rao <atti...@freebsd.org>: >> > 2009/6/29 pluknet <pluk...@gmail.com>: >> >> 2009/6/29 Attilio Rao <atti...@freebsd.org>: >> >>> 2009/6/29 pluknet <pluk...@gmail.com>: >> >>>> 2009/6/26 pluknet <pluk...@gmail.com>: >> >>>>> 2009/6/26 pluknet <pluk...@gmail.com>: >> >>>>>> Hello. >> >>>>>> >> >>>>>> While building a module on nfs mounted /usr/src >> >>>>>> I got an unkillable process waiting forever in bo_wwait. >> >>>>> >> >>>>> Small note: iface on NFS server has mtu changed from 1500 to 1450. >> >>>>> Can this be a source of the problem? >> >>>> >> >>>> This is 100% reproducible. Lock in the same place. Any hints? >> >>> >> >>> Can you also show the value of ps? >> >>> A precise map of what processes are doing would give an help. >> >>> Also would be useful to printout traces for other threads and not only >> >>> the stucked one. >> >>> >> >> >> >> >From another run: >> > >> > I'm unable to see who would be locking the buffer object in question. >> > Do you have INVARIANT_SUPPORT/INVARIANTS on? >> >> Yes, I do both. >> >> > What revision of /usr/src/sys/kern/vfs_bio.c are you running with? >> > >> >> As of 6.4-R: CVS rev 1.491.2.12.4.1 / SVN rev 183531. > > It seems that your changes of MTU cause nfs requests to never reach > network. bo_wwait is the state where thread waits for all outstanding > i/o on bufobj to drain. >
It appears that you are right. I found in tcpdump that nfs client tries to send UDP packets sized in 1500 bytes. 19:40:13.937085 IP (tos 0x0, ttl 64, id 4658, offset 0, flags [+], proto: UDP (17), length: 1500) client.1662412076 > server.nfs: 1472 write fh 1145,216955/1372174 1779 (1779) bytes @ 0 <unstable> While here I reverted mtu on NFS server back to 1500, then after some seconds "locked up" NFS client box continued to build a module as there were no any locking problems at all. So I understand this as defined behavior. -- wbr, pluknet _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
