On Wed, 2014-04-16 at 14:03 +1000, NeilBrown wrote: > sk_lock can be taken while reclaiming memory (in nfsd for loop-back > NFS mounts, and presumably in nfs), and memory can be allocated while > holding sk_lock, at least via: > > inet_listen -> inet_csk_listen_start ->reqsk_queue_alloc > > So to avoid deadlocks, always set PF_FSTRANS while holding sk_lock. > > This deadlock was found by lockdep.
Wow, this is adding expensive stuff in fast path, only for nfsd :( BTW, why should the current->flags should be saved on a socket field, and not a current->save_flags. This really looks a thread property, not a socket one. Why nfsd could not have PF_FSTRANS in its current->flags ? For applications handling millions of sockets, this makes a difference. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
