On Wed, Aug 8, 2012 at 2:33 PM, Myklebust, Trond <Trond.Myklebust@xxxxxxxxxx> wrote: > On Wed, 2012-08-08 at 14:15 -0400, Fred Isaman wrote: >> On Wed, Aug 8, 2012 at 2:03 PM, Myklebust, Trond >> <Trond.Myklebust@xxxxxxxxxx> wrote: >> > On Wed, 2012-08-08 at 13:51 -0400, Fred Isaman wrote: >> >> On Wed, Aug 8, 2012 at 1:34 PM, Myklebust, Trond >> >> <Trond.Myklebust@xxxxxxxxxx> wrote: >> >> > On Wed, 2012-08-08 at 18:48 +0200, Tigran Mkrtchyan wrote: >> >> >> Hi, >> >> >> >> >> >> It's quite some time without kernel panic reports from me .... >> >> >> >> >> >> Observer on MDS and DS shutdown during IO. >> >> >> >> >> >> This is with 3.5.0-2.fc17.x86_64 kernel. Line in code: >> >> >> >> >> >> nfs4proc.c:6252 : BUG_ON(!list_empty(&lo->plh_segs)); >> >> >> >> >> > >> >> > If the server doesn't return a stateid, then that is supposed to >> >> > indicate that it thinks that it doesn't hold any more layout segments >> >> > for this file. >> >> > To me, that indicates that we should be calling >> >> > mark_matching_lsegs_invalid() rather than Oopsing. >> >> > >> >> > Any dissenting voices from the pNFS crowd? >> >> > >> >> >> >> But this implies that the client thinks it has a layout which the >> >> server does not believe it has, which seems to me to imply an earlier >> >> bug. If you change to mark_matching_lsegs_invalid, I would suggest >> >> keeping a WARN_ON. >> > >> > We could possibly add a printk, but I don't see what value a WARN_ON >> > would have here: how is a stack dump going to be useful in debugging >> > this issue? >> > >> > Also, don't we sometimes expect this sort of thing to happen on >> > occasion? What if our layoutreturn ends up racing with the layout recall >> > following a DS shutdown? >> > >> >> Actually, I forgot about the whole LAYUTRETURN as fencing possibility. >> In that case, you can pretty easily hit the BUG_ON. Though I claim >> that, while calling mark_matching_lsegs_invalid doesn't hurt, it >> should be unnecessary. > > Right... So maybe just a dprintk() for debugging purposes? > > BTW: Why shouldn't we do the mark_matching_lsegs_invalid? If not, then > we will need either to do an extra layoutreturn or fail a read/write > attempt to the DS in order to figure out that the stateid is now > invalid. > They should have already been marked as invalid, and are just waiting on io to finish for release. Fred -- 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
