Thanks, applying.--b. On Mon, May 11, 2020 at 08:10:54AM -0400, Masayoshi Mizuma wrote: > On Fri, May 08, 2020 at 06:19:35PM -0400, J. Bruce Fields wrote: > > From: "J. Bruce Fields" <bfields@xxxxxxxxxx> > > > > We add the new state to the nfsi->open_states list, making it > > potentially visible to other threads, before we've finished initializing > > it. > > > > That wasn't a problem when all the readers were also taking the i_lock > > (as we do here), but since we switched to RCU, there's now a possibility > > that a reader could see the partially initialized state. > > > > Symptoms observed were a crash when another thread called > > nfs4_get_valid_delegation() on a NULL inode. > > > > Fixes: 9ae075fdd190 "NFSv4: Convert open state lookup to use RCU" > > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> > > --- > > fs/nfs/nfs4state.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c > > index ac93715c05a4..a8dc25ce48bb 100644 > > --- a/fs/nfs/nfs4state.c > > +++ b/fs/nfs/nfs4state.c > > @@ -734,9 +734,9 @@ nfs4_get_open_state(struct inode *inode, struct nfs4_state_owner *owner) > > state = new; > > state->owner = owner; > > atomic_inc(&owner->so_count); > > - list_add_rcu(&state->inode_states, &nfsi->open_states); > > ihold(inode); > > state->inode = inode; > > + list_add_rcu(&state->inode_states, &nfsi->open_states); > > spin_unlock(&inode->i_lock); > > /* Note: The reclaim code dictates that we add stateless > > * and read-only stateids to the end of the list */ > > -- > > Thank you for posting the patch! It works for our box. > Please feel free to add: > > Reviewed-by: Seiichi Ikarashi <s.ikarashi@xxxxxxxxxxx> > Tested-by: Daisuke Matsuda <matsuda-daisuke@xxxxxxxxxxx> > Tested-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx> > > Without the patch, the system which is a NFSv4 client has been > crashed randomly. The panic log is such as: > > BUG: unable to handle page fault for address: ffffffffffffffb0 > ... > RIP: 0010:nfs4_get_valid_delegation+0x6/0x30 [nfsv4] > ... > Call Trace: > nfs4_open_prepare+0x80/0x1c0 [nfsv4] > __rpc_execute+0x75/0x390 [sunrpc] > ? finish_task_switch+0x75/0x260 > rpc_async_schedule+0x29/0x40 [sunrpc] > process_one_work+0x1ad/0x370 > worker_thread+0x30/0x390 > ? create_worker+0x1a0/0x1a0 > kthread+0x10c/0x130 > ? kthread_park+0x80/0x80 > ret_from_fork+0x22/0x30 > > After applied the patch, the panic is gone. > > Thanks! > Masa
