Hello, Thanks for report. I suspect this bug got lost in the noise of linux-kernel. Adding more relevant lists and people to CC. Honza On Thu 20-10-16 15:24:37, Darren Austin wrote: > [ Please CC me with any replies as I will be leaving the list shortly ] > > Hi, > I'm not sure if this is the best place to report an issue i've discovered > with the kernel and the 'fsc' mount option - please let me know if there is > some other mailing list or person I should be notifying about this. > > The bug appears (at least for me) when using an NFS server, and a client > which mounts an export from that server with the 'fsc' option (whether or > not the fscache daemon is running or not). It also seems easiest to trigger > using the 'nano' editor, but other commands will trigger it randomly. > > I've tested this bug on the Ubuntu 1610 kernel (4.8.0) and with the 4.8.2 > kernel from http://kernel.ubuntu.com/~kernel-ppa/mainline/. The latter > purports to be a kernel built from the unmodified kernel source, and simply > packaged in a .deb, so this isn't a Ubuntu kernel problem. Unless the > problem has been corrected in the 4.9 series, I suspect the bug may also > persist there - i've not had the opportunity to check 4.9.x kernels as yet. > > I can repeatidly reproduce this bug on my system, so it's definitely not a > one off - it causes a kernel panic and complete lock-up every time. > > The NFS share I tested with is exported with options: > rw,async,insecure,insecure_locks,no_root_squash,anongid=99,anonuid=99,no_subtree_check > (but the export options don't seem to matter to trigger the bug) > and mounted on the client with options: > vers=4,hard,intr,acl,rw,fsc > via the Linux automounter (but the issue persists on mounts from fstab or > when mounted manually). > > To reproduce the bug is quite simple... > 1) Set up the server export and client mount as detailed above. > 2) From the console (or in a terminal; but I only tested this once) in the > directory where you've mounted the NFS share, run: > nano testfile.txt > and add write some text to the file. > 2) Save the file and exit (Ctl+X is how I did it). > 3) When back at the prompt, immediately hit the up arrow on the keyboard (to > load the last typed command into the buffer) and hit enter. > 4) Watch as the pretty text of the panic scrolls by :) > > With the help of people on the nano-dev mailing list, I figured out that > it's the 'fsc' option which causes the panic - repeated tests without that > option active do not trigger it. However, this is /not/ a nano specific bug > - it can be triggered by any command used on the mount. And besides, nano > shouldn't be able to take down the system :) > > If any further information is required, please don't hesitate to reply. > > Darren. -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- 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
