On Wed, 2008-06-04 at 20:35 -0400, Jeff Layton wrote: > On Thu, 5 Jun 2008 00:33:54 +0100 > "Daniel J Blueman" <daniel.blueman@xxxxxxxxx> wrote: > > > Having experienced 'mount.nfs4: internal error' when mounting nfsv4 in > > the past, I have a minimal test-case I sometimes run: > > > > $ while :; do mount -t nfs4 filer:/store /store; umount /store; done > > > > After ~100 iterations, I saw the 'mount.nfs4: internal error', > > followed by symptoms of memory corruption [1], a locking issue with > > the reporting [2] and another (related?) memory-corruption issue > > (off-by-1?) [3]. A little analysis shows memory being overwritten by > > (likely) a poison value, which gets complicated if it's not > > use-after-free... > > > > Anyone dare confirm this issue? NFSv4 server is x86-64 Ubuntu 8.04 > > 2.6.24-18, client U8.04 2.6.26-rc4; batteries included [4]. > > > > I'm happy to decode addresses, test patches etc. > > > > Daniel > > > > Looks like it fell down while trying to take down the kthread during a > failed mount attempt. I have to wonder if I might have introduced a > race when I changed nfs4 callback thread to kthread API. I think we may > need the BKL around the last 2 statements in the main callback thread > function. If you can easily reproduce this, could you test the > following patch and let me know if it helps? > > Note that this patch is entirely untested, so test it someplace > non-critical ;-). > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > > diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c > index c1e7c83..a3e83f9 100644 > --- a/fs/nfs/callback.c > +++ b/fs/nfs/callback.c > @@ -90,9 +90,9 @@ nfs_callback_svc(void *vrqstp) > preverr = err; > svc_process(rqstp); > } > - unlock_kernel(); > nfs_callback_info.task = NULL; > svc_exit_thread(rqstp); > + unlock_kernel(); > return 0; > } We certainly need to protect nfs_callback_info.task (and I believe I explained this earlier), but why do we need to protect svc_exit_thread? Also, looking at the general use of the BKL in that code, I thought we agreed that there was no need to hold the BKL while taking the nfs_callback_mutex? Trond -- 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
